Annual/Termination Reports:

[01/22/2004] [01/24/2005] [01/12/2007] [01/12/2007] [09/23/2008]

Report Information

Participants

Aiken, Robert (KS-AES); Chollet, Raymond (NE-AES); Cushman, John (NV-AES); Daley, Larry (OR-AES); Edwards, Gerald (WA-AES); Huber, Steve (IL-ARS, Urbana); Koch, Karen (FL-AES); Loescher, Wayne (MI -AES); Markwell, John (NE-AES); Moore, Brandon (SC-AES); Portis, Archie (IL-ARS, Urbana); Preiss, Jack (MI-AES)

Brief Summary of Minutes

Annual Meeting Date and Location: November 22, 2003; Nevada AES host; Best Western Airport Plaza Hotel, Reno, Nevada

Attending members: Dr. Robert Aiken (Kansas AES), Dr. Ray Chollet (Nebraska AES), Dr. John Cushman (Nevada AES), Dr. Larry Daley (Oregon AES), Dr. Gerry Edwards (Washington State AES), Dr. Steve Huber (Illinois AES), Dr. Karen Koch (Florida AES), Dr. Wayne Loescher (Michigan State AES), Dr. John Markwell (Nebraska AES), Dr. Brandon Moore (South Carolina AES), Dr. Archie Portis (Illinois AES), Dr. Jack Preiss (Michigan State AES)

New Members: Dr. Robert Aiken (Kansas AES)

Retiring members of the NC-1-142 Group: Dr. Jack Shannon (Pennsylvania AES)

Attending guests interested in NC-1-142 membership: Dr. Jeff Harper (Nevada AES), Dr. Ron Mittler (Nevada AES)

The annual meeting was called to order by Dr. John Cushman, Chair. It was attended by all members listed above, although our Administrative Advisor, Forrest Chumley and CSREES Representative, Gail McLean were both unable to attend. Each member presented a 25 min overview of their previous years accomplishments, followed by questions and comments following earch presentation. In his place, Dr. Ron Pardini, Associate Director, Nevada AES welcomed the group to Reno and gave a short overview of the activities of the Nevada AES. Each member the presented a 25 min overview of their previous years accomplishments, followed by questions and comments following earch presentation. Scientific discussions began during the informal breakfast period, and continued during breaks, lunch, and dinner. The on-site arrangements for these events facilitated the extent of discussions and ease of interactions. Presentations occurred from 8:30 am to 6:00 pm, although collectively the talks continued for about an hour longer than anticipated. This was due largely to the extent of interactive discussion generated in association with the presentations.

The business meeting was convened after the talks and lasted approximately an hour. The primary issues were to 1) election of new officers, 2) appraise sites and formats for future meetings, 3) increase attendance, 4) discuss candidates for incoming and outgoing membership, and 5) discuss new business.

The group concurred that the previously-outlined plan for identifying meeting sites and candidates for the Executive Committee needed to be revisited. After some discussion, the Florida AES was volunteered as a meeting site for 2005 by Dr. Karen E. Koch, who also agreed to serve as the new secretary. The period of service for this position was advanced to that of the current year by the absence of Dr. Robert Houtz of Kentucky AES. Dr. Robert Spreitzer of Nebraska AES was nominated to serve as secretary in 2006.

For future meetings, the recurring issue was raised of whether it would be better to visit actual AES campus sites or to use hotels at readily accessible locales. All concurred that there were considerable advantages to meeting at campus sites, because this facilitated interactions with scientists at the host institution (especially collaborations with the hosting NC-1-142 member). However, the group also felt that these advantages were generally outweighed by the greater time and travel costs involved in reaching the universities. It was also noted that ease of accessibility and proximity to a major airport have been important to members past decisions of whether to attend or not, since significant differences in time can be involved. A final consideration was that of the broad geographic distribution of our now nation-wide project, and the travel challenges this poses for some members. The discussion was especially relevant to arrangements for the 2004 meeting to be hosted by the South Carolina AES. Brandon Moore agreed to investigate sites with these considerations in mind, yet also noted that the difficulties involved in hosting an off-site meeting could increase markedly with distance.

Several potential means of increasing attendance were discussed.
-- Ease of travel and efficient time use were considered important. The possibility of shifting the meeting date was also raised.
-- The date of the meeting was also tentatively shifted to one week earlier. Several members reported travel difficulties apparently due to the weekend of the meeting being so close to Thanksgiving. Costs were higher and availability limited. A date one week earlier was suggested, and there was a general consensus that this was worth trying.
-- Membership issues were also viewed as relevant to attendance and received additional attention.

Significant discussion was dedicated to means of identifying vigorous, new members (especially in the area of Objective 1: Photochemistry and the Biogenesis of the Photosynthetic Apparatus) and also of linking attendance to viable membership. The group was enthused about research presented by the two prospective new members from the Nevada AES, and their work was discussed. In addition, members were asked to think about potential new collaborators in the area of photobiology.

The issue of linking membership to attendance was discussed. It was suggest that our Administrative Advisor, Dr. Forrest Chumley, could help by officially contacting non-attending members (see list above) and their Experiment Station Directors to request an explanation of their lack of attendance. Initially this would be to encourage attendance, and if non-involvement persisted, to suggest or discuss resignation. This has been a consistently important issue

Several items of new business were discussed. For the new five year NC-1-142 project initiated in October 2002, the development of a project website to be located at Kansas State University was discussed. Possible information to be presented on the website might include a lay summary of the NC-1-142 project, citations of publications, a summary of key impacts (usefulness of findings) that could be presented as bullet points. It was suggested that these items be included in the annual reports to facilitate the posting of this information to the website. It was also suggested that the project website have links to the Long laboratory, in particular, as well the websites of all project participants.

Most discussion addressed Objectives 2, 3, and 4, which respectively were Photosynthetic capture and photorespiratory release of CO2, Mechanisms regulating photosynthate partitioning, and Developmental and environmental limitations to photosynthesis. The greatest number of attendees at this years meeting worked in some way on Objective 3 (partitioning), but overlapping interests and vigorous discussion was evident in all three areas. As noted for the previous meeting (2002) concern was expressed at our need to either acquire greater expertise in the area of Objective 1 (Photochemistry and Biogenesis of the Photosynthetic Apparatus) or omit this area from the project.

Key discussions centered on the science outlined in reports from the attending AES representatives and the visiting candidates for new membership. The primary issues of the business meeting are enumerated above.

As decided by NC-1-142 participants, the leadership succession will progress from Dr. John Cushman (Nevada AES) departing Chair of the 2003 meeting, to Dr. Brandon Moore (South Carolina AES) incoming Chair and host for the 2004 meeting. Dr. Karen Koch (Florida AES) will become vice-chair, and will also continue to serve as secretary for the 2004 meeting unless a suitable candidate can be identified at its opening. As noted above, the weekend selected for the 2004 meeting will be ONE WEEK EARLIER than in past years, now two weekends prior to the Thanksgiving holiday. The date will be Saturday, November 13, 2004.

Accomplishments

Photosynthesis is a unique and fundamental process on which most life forms on earth depend. However, this process can be dramatically limited by environmental constraints resulting in rates of agricultural productivity that are far lower than optimal rates. The research objectives of this regional project are to improve our understanding of the biochemical regulation of important photosynthetic enzymes and how environmental and developmental signals affect photosynthetic performance at the molecular genetic level across four different areas of photosynthetic research.<br /> <br /> Objective 1: Photochemistry and the biogenesis of the photosynthetic apparatus. Collaborating units include AES and/or ARS-USDA: IA-AES (Rodermel).<br /> <br /> A major focus of research for IA-AES (Rodermel) continues to be improving our understanding of the control of thylakoid membrane biogenesis and the mechanisms that coordinate gene expression between the nucleus-cytoplasm and the plastid. The model system being used the immutans (im) variegation mutant of Arabidopsis, which contains green and white sectored leaves. White cells contain plastids with abnormal plastids that lack internal membrane structures and accumulate phytoene, a colorless C40 carotenoid intermediate, indicating that im is impaired in the activity of phytoene desaturase (PDS), the plastid enzyme that converts phytoene to zeta-carotene. The IMMUTANS locus encodes for a chloroplast homolog of the mitochondrial alternative oxidase (AOX) and this gene product may act as a terminal oxidase in plastid membranes. This same terminal oxidase is expected to function in the redox pathway that desaturates phytoene. The tomato ghost and Arabidopsis immutans variegation mutants define orthologous genes, opening the possibility of using tomato fruit ripening as a model to explore GHOST (IMMUTANS) protein function. The GHOST gene product plays a critical role in the biogenesis of chloroplasts and chromoplasts and likely is involved in carotenogenesis. To identify other gene products that may interact with IM, suppressor screens have been initiated and have resulted in the isolation of three suppressor mutations. Map-based cloning of one of the suppressors is near completion. <br /> <br /> Objective 2: Photosynthetic Capture and Photorespiratory Release of CO2. <br /> Collaborating units include AES and/or ARS-USDA: IL (Portis), MO (Randall), NE (Chollet, Spreitzer), NV (Cushman), OR-AES (Daley).<br /> <br /> Investigations at IL-ARS (Portis) into the response of Rubisco activase to high temperature, its interactions with Rubisco, and improved strategies for genetically engineering Rubisco have progressed significantly this past year. At elevated temperatures, Rubisco activity becomes inactivated by alterations or reductions in Rubisco activase enzyme. These results suggest that activase enzyme plays an important role in limiting the inhibition of photosynthesis at high temperatures. Manipulation of the degree of polyunsaturation of thylakoid lipids also was found to inhibit net photosynthesis. As part of a long-term collaboration with NE-AES (Spreitzer) the effects of replacing specific amino acid residues of the Chlamydomonas Rubisco large subunit residues with tobacco residues unique to the Solanaceae were investigated. To date, such changes have had only minimal effect in altering the specificity with spinach and tobacco activase. Efforts to continue the identification of residues at the site of Rubisco interaction with activase remain under investigation. In collaboration with Dr. Long's (IL-AES) group, a steady-state biochemical model for leaf photosynthesis was coupled to a canopy biophysical microclimate model and used to explore how theoretical changes in the kinetic parameters of Rubisco or replacing the typical crop Rubisco with naturally occurring Rubiscos will increase total crop carbon gain. As the genetic engineering of Rubisco is proving to be difficult and time consuming, such modeling studies will facilitate the selection of modified Rubiscos.<br /> <br /> Studies at MO-AES (Randall) investigating the mitochondrial pyruvate dehydrogenase complex (mtPDC), which links glycolysis to the Krebs cycle by catalyzing the oxidative decarboxylation of pyruvate to acetyl-CoA. The reversible phosphorylation of mtPDC, by pyruvate dehydrogenase kinase (PDK), provides a cardinal regulatory mechanism for the interaction of respiratory and photorespiratory metabolism. PDK lacks the 12 signature domains/motifs of the Ser/Thr protein kinase family, and instead, has the 5 signature motifs of the histidine protein kinases (HPKs) or two-component protein kinases. However, PDKs are a unique type of protein kinase having a His-kinase like sequence, but Ser-kinase activity. PDK is a member of the ATPase/kinase superfamily, which includes ATPases, Gyrase, HSP90, and the PHKs. In silco analysis has identified Lys241 as a potential catalytic residue and mutagenesis to Ala yielded a PDK with highly reduced affinity for ATP and low catalytic efficiency. Phosphorylation sites on the Arabidopsis E1alpha subunit of mtPDC have been mapped and the influence of this phosphorylation by E2 subunits have been investigated. To investigate the functional role of PDK in vivo, homozygous knockout lines of PDK have been generated and phenotypic characterization is underway. <br /> <br /> Investigations by NE-AES (Spreitzer) into the structure-function relationships of Rubisco have continued to add new insights into the catalytic efficiency and CO2/O2 specificity of Rubisco. These investigations have been performed in the green algal model, Chlamydomonas reinhardtii, because non-functional mutants of Rubisco can be maintained and subunits can be replaced at will in order to conduct genetic screens for the isolation of second-site suppressor mutations as a means for identifying complementing structural interactions. Comparative phylogenetic analysis of Rubisco large-subunit sequences has revealed 13 residues that differ in regions previously shown by mutant screening to influence CO2/O2 specificity. Mutant screens to identify compensatory changes in the small subunit of Chlamydomonas are underway. In collaboration with Dr. Inger Andersson (Swedish Agricultural University, Uppsala), X-ray crystal data sets have been obtained for more than 10 large-subunit mutant enzymes, and complete structures have been solved for six of them. Collaborative research with IL-ARS (Portis) has continued to focus on a Rubisco large-subunit loop that interacts with Rubisco activase. Additional substitutions in this loop have failed to alter specificity for activase, indicating that overall structure may be more important than individual residues. Work is in progress to replace this entire loop with the loops characteristic of divergent land-plant Rubisco enzymes.<br /> <br /> Research by NE-AES (Chollet) had resulted in significant new insights into the structure-function relationships and regulatory phosphorylation of phosphoenolpyruvate carboxylase (PEPC) by PEPC kinase (PpcK). Two different PEPC isogenes were characterized from Chlamydomonas reinhardtii, representing the first PEPC genes described from any algal species. In related work on green-plant PEPC, detailed investigation of the sorghum recombinant C4 enzyme using site-directed mutagenesis revealed that the conserved, C-terminal QNTG-tetrapeptide is important for its influence on catalysis. Chollet's group also reported on the molecular cloning and expression analysis of phosphoenolpyruvate carboxylase kinase (PPCK) in Soybean (Glycine max). Four members of this small multigene family with varying expression patterns have now been described. Investigations into the biochemical, kinetic, and immunological analyses of a soluble, recombinant form of ice plant CAM PpcK with NV-AES (Cushman) were completed. Collaborative studies with Prof. Chris Chastain and his many undergraduate researchers at Minnesota State University-Moorhead into the striking up-/down-regulation by reversible phosphorylation of a strictly conserved Thr residue of plastidic pyruvate orthophosphate dikinase (PPDK), one of a few flux-controlling enzymes in C4 photosynthesis, have shown that the posttranslational modification of plastidic PPDK by its bifunctional regulatory protein (RP) is not restricted to green leaves of C4 and C3 plants, but also is present in plastids of developing cereal seeds.<br /> <br /> NV-AES (Cushman) has continued to conduct gene discovery through large-scale expressed sequence tag (EST) sequencing in the common ice plant, Mesembryanthemum crystallinum as a Crassulacean acid metabolism (CAM) model. This work has facilitated the molecular cloning of genes encoding circadian clock components in collaboration with the Hartwell (University of York, UK) and Bohnert (IL-NAES) laboratories. Collaboration with the NE-AES (Chollet) resulted in the molecular cloning, expression and purification of a partially soluble, recombinant form of phosphoenolpyruvate carboxylase kinase (PPCK1) from the common ice plant. NV-AES has also continued analysis of CAM-defective mutants of M. crystallinum obtained by fast neutron (Nf) irradiated plant populations. Finally, in collaboration with the Winter group (Smithsonian Tropical Research Institute), we have conducted molecular phylogenetic analysis of 31 Panamanian Clusia species in parallel with photosynthetic pathway mapping along the C3 to CAM continuum based on 13C/12C ratios of plant carbon and found that CAM species distribute on distinct branches of the phylogenetic trees consistent with the polyphyletic origins of CAM allowing exploitation of an extended range of ecological opportunities. <br /> <br /> OR-AES (Daley) has continued investigations into the possible mechanisms capable of explaining the polyphyletic evolutionary origins of CAM.<br /> <br /> Finally, several NC-1-142 researchers, including those at NE-AES, KY-AES, and USDA/ARS-Urbana, have edited and/or co-authored a minireview series on the CO2/HCO3_-fixing enzymes in plants that is related directly to the overall focus of Objective 2.<br /> <br /> Objective 3: Mechanisms regulating photosynthate partitioning.<br /> Collaborating units include AES and/or ARS-USDA: FL-AES (Koch), IA-AES (Knapp and Rodermel), IL-AES/ARS (Huber), MI-AES (Loescher and Preiss), SC-AES (Moore), WA-AES (Edwards and Okita).<br /> <br /> Sucrose cleavage by invertase generates hexoses essential for growth and sugar signaling during development of maize kernels. FL-AES (Koch) has tested ABA responsiveness on the mRNA abundance changes of invertases during early kernel development in maize wildtype ovaries and those of vp1 (viviparous1) ABA-insensitive mutants. The difference in invertase expression between WT and vp1 kernels provides evidence for a role of ABA-signaling in crosstalk with sugar sensing during early seed development. The interface between sugar and ABA signaling is also being studied in Arabidopsis in collaboration with IA-AES (Rodermel) in which the mRNA abundance patterns of 8 invertase family members is under investigation. The role of sucrose synthase and its regulation is also being investigated through the study of the growth, development, and cell wall composition of double and single mutants deficient in functional Sus1, Sh1, or both sucrose synthase genes. QTLs for plant height have been identified near both the SUS1 and SH1 loci. Work is in progress to determine the degree to which sucrose synthase may be contributing to these QTLs. The Koch lab, in collaboration with IL-AES (Huber), is also studying the effects of specifically-altered sucrose synthase transgenes in a double mutant sucrose synthase background to examine the effects of alterations in sucrose synthase phosphorylation in vivo.<br /> <br /> The IA-AES (Knapp) laboratory continues to investigate the responses of maize to various low temperature stress. Studies completed this year evaluated stress duration on the growth, electrical conductivity, and potassium leakage from the fourth leaf of maize inbreds that putatively differ in low temperature stress tolerance. The percent electrical conductivity (EC) values of inbreds from the control treatments were not significantly different under normal temperature conditions, significant differences were observed under low temperature conditions. While EC values provide a useful indirect measure of relative cold tolerance, potassium leakage does not appear to be as good a screening tool as EC. However, EC evaluation appeared to be influenced by leaf structural characters and there was not a good correlation between EC values and dry weight measurements. Thus, more work is needed to refine stress scenarios and screening techniques to reliably rank inbreds.<br /> <br /> IL-AES/ARS (Huber) have continued their investigations into the regulatory control mechanisms of sucrose synthase, an important enzyme responsible for sucrose metabolism and partitioning of carbon in various metabolic and biosynthetic pathways in growing plant organs, such as developing seeds. Sucrose synthase is phosphorylated at Ser15, close to the N-terminus. Sequence-specific antibodies were used to show that phosphorylation affects the conformation of the amino terminus of the protein, most likely by favoring an open-coil conformation rather than an alpha-helix. This conformational change may be responsible for an increase in enzyme activity and changes in binding to membranes that are observed. Calcium-dependent protein kinases (CDPKs) are thought to phosphorylate metabolic enzymes, such as nitrate reductase (NR), sucrose synthase (SUS) and sucrose-phosphate synthase (SPS). The Huber lab has characterized several new recognition motifs for phosphorylation sites in cellular proteins by CDPKs. The eukaryotic regulatory protein 14-3-3 is involved in many important plant cellular processes including regulation of nitrate assimilation, through inhibition of phosphorylated nitrate reductase (pNR) in darkened leaves. Structure-function studies of the 14-3-3 protein showed that the C-terminal tail functions as an autoinhibitor, that blocks binding to nitrate reductase when magnesium is not present. These results increase our understanding of the molecular mechanisms that control 14-3-3 binding, and also provide unique experimental tools to use in future experiments to study the function of 14-3-3 proteins in vivo using transgenic plants.<br /> <br /> MI-AES (Loescher) has continued their investigations on alcohol metabolism in the family Rosaceae, which includes the majority of the world's temperate tree fruits. Progress to date includes identification and characterization of a number of sorbitol transporters in fruit and other sink tissues in apple and cherry. Genes for these sorbitol transporters are quite similar, but they are often expressed at different stages of leaf and fruit development and in some cases their expression is correlated with changes in the sink's capacity to attract and utilize photosynthetic products. Expression of the gene encoding mannitol 6-phosphate reductase mannitol metabolism from celery in Arabidopsis showed that the transgenic plants produced mannitol and had higher tolerance to salinity than wildtype plants that did not produce mannitol. Analysis of Arabidopsis transformants was conducted in collaboration with WA-AES (Edwards) laboratory. <br /> <br /> WA-AES (Edwards and Okita) have collaborated with MI-AES (Loescher) to improve the salt tolerance of Arabidopsis by expression of the mannitol 6-P reductase gene from celery. The transformed plants produced mannitol and had higher tolerance to salinity than wildtype plants that did not produce mannitol. Other research by Edwards and Okita was directed at understanding the significance of starch biosynthesis in source (leaves) and sink (seed) tissues to photosynthesis, plant growth and crop production. Mutants with down-regulated forms ADP-glucose pyrophosphorylase (AGP), a key enzyme in regulation of starch biosynthesis in plants, showed reduced starch synthesis, with corresponding reductions in CO2 assimilation rates, and cumulative leaf area when compared to wildtype plants. Mutants containing single amino acid changes in the large subunit L1 gene of AGP were expressed in a mutant background that lacks the large subunit of AGP and only produces about half as much starch as the wildtype. Transformants were selected showing high AGP activities compared to wildtype plants and are now the subject of current investigations.<br /> <br /> MI-AES (Preiss) has investigated structure-function relationships of glycogen synthase (GS) from Escherichia coli and ADP-glucose pyrophosphorylase (AGP) from Arabidopsis. These enzymes catalyze the rate-limiting and committed steps in glycogen biosynthesis in bacteria and starch biosynthesis in plants, respectively. Comprehensive mutagenesis studies have identified specific residues critical for the affinity of glycogen synthase for ADPGlc, glucose-1-P binding site, and catalysis. Recent studies have shown that the Arabidopsis AGP catalytic subunit in its interaction with each of the four regulatory large subunits differentially present in a tissue-specific manner, confer different kinetic properties with respect to apparent affinities for the allosteric activator, 3PGA and for the inhibitor, Pi. The large subunit mainly present in leaf confers on the catalytic subunit the highest affinity for the allosteric effectors as well as for the substrates ATP and glucose-1-P when compared to the effects of the large subunits mainly present in the sink tissues. In an exciting development, the crystal structure of the potato tuber AGP catalytic subunit was recently been determined at 2.3 Å resolution and will now permit the location of enzyme substrates within the context of the three-dimensional structure and its relation to the catalytic residue, Asp145. <br /> <br /> SC-AES (Moore) is a new addition to the project this year. Research efforts focus on the characterization of the regulatory mechanisms that control sucrose and starch synthesis and degradation. Studies in Arabidopsis have identified hexokinase (HXK1) as a key protein involved both in glucose metabolism and glucose signaling. The cellular context for glucose signaling by HXK1 remains unclear. Transiently expressed HXK1-GFP is associated with mesophyll mitochondria, suggesting that glucose signaling somehow involves a mitochondrial function. To identify other possible interacting proteins, an affinity tagged version of HXK1 was used to isolate about 30 proteins, including a number of chloroplast and mitochondrial proteins, but no obvious transduction proteins. A related possibility for mitochondria functioning as an organizing center is that they may move directly to or from the nucleus, thereby facilitating signal transduction. Both Arabidopsis and pea leaf mitochondria have protein that cross-reacts with anti-F-actin antibody. Vegetative actin also was identified from the microsequencing experiment, as being associated with an HXK1-protein complex. Thus, a working hypothesis is that glucose signal transduction may involve mitochondria movement by actin filaments to/from the nucleus.<br /> <br /> Objective 4: Developmental and environmental limitations to photosynthesis.<br /> Collaborating units include AES and/or ARS-USDA: Guam AES (Marler), IL-AES (Below), KS-AES (Aiken and Knapp), MN-AES (Jones), NE-AES (Markwell), NV-AES (Cushman), PA-AES (Guiltinan).<br /> <br /> Research efforts at NE-AES (Markwell) are directed toward environmental limitations included collaboration with entomologists at the University of Nebraska-Lincoln and the University of Montana. Following up on the initial observation that methanol treatment may enhance plant growth under water-limiting conditions, through increased leaf formate dehydrogenase (FDH) enzyme activity, more detailed molecular genetic and biochemical investigations into the regulation of this enzyme were conducted. FDH is an NAD-dependent enzyme that catalyzes the oxidation of formate to CO2 in the mitochondria of higher plants. Although the enzyme is specific for its NAD cofactor and did not utilize NADP+ for the oxidation of formate, NADPH appeared to be an inhibitor of the NAD+-dependent formate oxidation. Upon heating, however, it is able to use NADP+ as a substrate for the oxidation of formate. This ability of the FDH to assume a conformation able to use NADP+ in a chloroplastic compartment is of interest and will be the focus of future in vitro mutagenesis studies. To be able to initiate in vitro mutagenic studies on cofactor specificity and stability of the Arabidopsis FDH, optimal conditions for the production of an active enzyme in Escherichia coli are being investigated. <br /> <br /> MN-AES (Jones) investigated the effects of high temperature during maize endosperm cell division on protein accumulation. This study confirmed that a 2 or 4-day heat stress caused a 20 to 48% reduction in total protein content. Specifically, zein content was reduced by an average of 53%, but zein composition was only mildly affected whereas, the concentration of glutelins and albumins plus globulins was negatively affected. Cytokinin oxidase (CKO) is the principal enzyme involved in cytokinin catabolism. In collaboration with Pioneer Hi-Bred International, a study characterizing cytokinin oxidase gene expression, localization and induction confirmed that cytokinin oxidase was expressed in the vascular bundle of kernels, coleoptiles and leaves and was developmentally regulated in a manner that is correlated with cytokinin levels and cytokinin oxidase activity. Research also continued in the use of transgenic plants over-expressing the bacterial form of the cytokinin synthesis gene (isopentyl transferase-ipt) to manipulate maize kernel endogenous cytokinin levels in planta. Gene dose experiments also revealed that only one dose of the ipt gene was sufficient to result in the highest level of ipt expression. These data suggest that expression or over-expression of cytokinin synthesis genes in specific kernel component tissues may be a viable molecular approach to increasing endogenous cytokinin levels during kernel development and thus stabilizing grain yield of maize against the periodic occurrence of heat stress or more long-term global climate change.<br /> <br /> KS-AES (Knapp) has continued to analyze the limitations and environmental factors that influence photosynthetic productivity at the whole plant and canopy levels with particular emphasis on the study of ecosystem responses to altered precipitation and temperature patterns (climate change factors). Precipitation has been manipulated experimentally to identify, quantify, and understand water limitations to photosynthesis and productivity in the native tallgrass prairie ecosystem of Kansas. Increasing the variability of rainfall patterns altered photosynthetic rates and aboveground productivity in this grassland. The primary mechanism identified was increased water stress as soil nitrogen availability was actually increased under a more variable rainfall regime. A warming treatment was also nested within current rainfall treatments to study the interactive effects of these two predicted climate change factors on carbon uptake at the plant and ecosystem level. Impacts of climate change on the establishment of trees in this grassland ecosystem were also investigated. Woody plant encroachment into these productive ecosystems represents a major threat to their long-term sustainability. Results indicated that even though photosynthetic rates were negatively impacted in drought years by temperature and water stress, survivorship was high. This suggests that projected climate changes will not slow the expansion of forest into grassland. <br /> <br /> KS-AES (Aiken) has focused on temperature stress effects on the germination and heterotrophic growth as well as photosynthesis and fluorescence characteristics in a population of recombinant inbred lines of sorghum. Grain sorghum is known for drought tolerance, though not cold tolerance. Studies of temperature and germplasm effects on sorghum germination and heterotrophic growth demonstrated that both male and female parents contributed to cold tolerance. Mapping of the relative positions of thermotolerance traits in the sorghum genome is underway using molecular markers developed for 112 recombinant inbred lines. Candidate traits include leaf development rate, photosynthetic and fluorescence characteristics and responses to chilling, electrolyte leakage following chilling, and potential release of hydrocyanic acid. Greenhouse and field results are under analysis, in collaboration with M. Tuinstra's lab. Photosynthesis and fluorescence measurements on leaves of selected RILs indicate a negative correlation between internal leaf pCO2 and transpiration efficiency, normalized for vapor pressure deficits. Principle component analysis of six photosynthesis and fluorescence parameters indicated diverging characteristics.<br /> <br /> NV-AES (Cushman) showed that transgenic wheat plants producing mannitol exhibit improved tolerance to artificial water-deficit and salinity stress presumably through reducing the accumulation of hydroxyl radicals. Additional studies were focused on understanding the functional roles of abiotic stress-protective proteins known as hydrophilins or late embryogenesis abundant (LEA) proteins. Detailed structural characterization of group 1 and group 2 LEA proteins showed that both proteins exist in equilibrium between two conformational states: unordered and left-handed extended helical or poly-L-proline-type II (PII) structures. PII structures are solvent exposed, and like unordered structures, can interact efficiently with water. Such proteins may carry out a variety of functional roles including the stabilization of enzymes and membranes during tissue desiccation or the binding of divalent metals to reduce the production of free radical formation and resultant oxidative damage to macromolecules. <br /> <br /> Guam AES (Marler) studied the fluctuations in non-structural carbohydrates in papaya plants following manipulation of source-sink balance by leaf removal in collaboration with Cecil Stushnoff, Colorado State University. Source-sink relationships play a key role in papaya plant recovery from any environmental stress, especially one that severely impairs source size or function. Starch pools were minimal and unchanged following defoliation. Lateral roots had higher concentration than taproots or stems, but maximum levels were only 5 mg/g. Glucose and fructose concentration was similar for taproot and stem tissue, but was lower in lateral root tissue. Alternatively, sucrose concentration was similar for lateral root, taproot, and stem tissue. Other saccharides were minimal or undetectable in papaya tissues. The increased need for carbohydrates for reconstructing source leaves following foliage injury was not apparently met by mobilization of soluble carbohydrates from stem or root tissue. <br /> <br /> IL-AES (Below) employed the Illinois High Protein (IHP) and Illinois Low Protein (ILP) strains in a variety of studies investigating the relative contributions of genotype and vegetative source versus kernel sink control over maize grain composition. The interactive effects of genotype and N fertilizer on grain yield, yield components, and grain composition were investigated by evaluating hybrids. All hybrids except ILP showing increased grain protein in response to N. Protein concentration was inversely proportional to starch concentration and grain yield. The yield decreases observed for Protein Strain hybrids relative to a current elite hybrid were due primarily to reductions in kernel weight rather than kernel number. The three hybrids with low grain protein concentrations (ILP, IRHP, and elite) exhibited a consistent strong yield response to N. These results demonstrate the potential genetic variability for grain protein and starch concentrations in maize hybrids and the interactive effects of both genotype and N supply on grain yield and composition. A separate study examined the role of the cob in the movement of N assimilates into developing maize ovules to improve our understanding of how N assimilates move through the young earshoot to assist in kernel set and subsequent kernel growth. The young cob was found to have active enzymes that transform amino acids during early reproductive development, which may allow for a continual flow of these principal amino acids from the phloem for sustained reproductive growth. <br /> <br /> PA-AES (Guiltinan) continued the molecular genetic analysis of the maize starch branching enzymes (SBEs) by determining the effect of SBE gene dosage on starch branching architecture, both for single genes and for multiple dosage combinations of three different starch branching enzyme genes in order to test the hypothesis that manipulation of dosage of these three SBE isoforms will produce starches with novel branching architectures. In addition, the effects of a starch debranching enzymes (SDEs) and starch synthase on starch branching enzyme isoforms and starch branching architecture was also studied in order to test the hypothesis that varied dosage of this gene in combination with varied dosage for individual SBE genes will produce novel starch with different branch lengths and also different branch patterns. Various combinations of SBE, SDE, and starch synthase mutants were constructed. Methods for the isolation and analysis of starch from single kernels were developed to follow starch structural phenotypes in segregating populations. Using modified zymogram analysis no pleiotropic effects within single SBE mutants on the activity level of any of the SBE isoforms were observed. However, mutation in the gene encoding SBEIIb does result in a decrease in three starch synthase isoforms and a corresponding increase in a separate starch synthase activity. Analysis of the multiple mutant combinations will allow new insights into the interactions of the various starch biosynthetic enzymes.<br />

Publications

Abebe T, Guenzi AC, Martin B, Cushman JC (2003) Tolerance of mannitol-accumulating transgenic wheat to water stress and salinity. Plant Physiol. 131: 1748-1755.<br /> <br /> Aiken RM, Tuinstra MR, Kofoid KD, Stockton RD. (2003) Cold tolerance components in grain sorghum seedlings: Male and female contributions. Agronomy Abstracts. C02-aiken557267-oral.<br /> <br /> Aluru MR, Rodermel SR. (2003) Control of chloroplast redox by the IMMUTANS terminal oxidase. (Refereed review, Cover article). Physiologia Plantarum (in press)<br /> <br /> Aluru MR, Rodermel SR. (2003) Identification of IMMUTANS as a plastid terminal oxidase: its role in differentiation, carotenoid biosynthesis and chlororespiration. Recent Res. Devel. Plant Mol. Biol. 1: 39-55.<br /> <br /> Andersen MN, Asch F, Wu Y, Jensen CR, Naested H, Morgensen VO, Koch KE (2002) Soluble invertase expression is an early target of drought stress during the critical, abortion-sensitive phase of young ovary development in maize. Plant Physiol. 130: 591-604<br /> <br /> Artyusheva EG, Edwards GE, Pyankov VI. (2003) Photosynthesizing tissue development in C4 cotyledons of two Salsola species (Chenopodiaceae). Russian J. Plant Physiol. 50: 4-18.<br /> <br /> Baack R., Markwell J, Herman PL, Osterman JC. (2003) Kinetic behavior of the Arabidopsis thaliana leaf formate dehydrogenase is thermally sensitive. J. Plant Physiol. 160: 445-450.<br /> <br /> Ballicora MA, Iglesias AA, Preiss J. (2003) ADP-glucose Pyrophosphorylase; a Regulatory enzyme for Bacterial Glycogen Synthesis. Microbial & Molec. Biol. Rev. 67: 213-225<br /> <br /> Ballicora MA, Iglesias, AA, Preiss J. (2003) ADP-glucose Pyrophosphorylase; a Regulatory enzyme for Plant Starch Synthesis. Photosynthesis Research, In Press. <br /> <br /> Bassman J, Robberecht R, Edwards GE. (2003) Photosynthesis and growth in seedlings of five forest tree species with contrasting leaf anatomy subjected to supplemental UV-B radiation. Forest Science, 49: 176-187.<br /> <br /> Below FE, Seebauer JR, Uribelarrea M, Schneerman MC, Moose SP (2004) Physiological changes accompanying long-term selection for grain protein in maize. Plant Breeding Rev. (in press). <br /> <br /> Bergerou JA, Gentry LE, David MB, and Below FE, (2004) Role of N2 fixation in the soybean N credit in maize production. Plant and Soil (in press).<br /> <br /> Boxall SF, Bohnert HJ, Cushman JC, Hugh G. Nimmo HG, Hartwell J. (2003) Circadian clock-associated genes CCA1/LHY, TOC1, ELF4, ZTL, FKF1, GI, and ELF3 from Mesembryanthemum crystallinum during a stress-induced CAM shift. Submitted. [NC-142 collaborative research with IL-AES].<br /> <br /> Brugiere N, Jiao S, Hantke S, Zinselmeier C, Roessler J, Niu X, Jones RJ, Habben JE. (2003) Ctokinin oxidase (Ckx1-2) gene expresssion in Zea mays is localized to the vasculature, and is induced by cytokinins, abiotic stress and abscisic acid. Plant Physiol. 132: 1228-1240.<br /> <br /> Burger BT, Cross JM, Shaw JR, Caren JR, Greene TW, Okita TW, Hannah LC (2003) Relative turnover numbers of maize endosperm and potato tuber ADP glucose pyrophosphorylases in the absence and presence of 3-PGA. Planta 217: 449-456<br /> <br /> Chastain CJ, Chollet R. (2003) Regulation of pyruvate,orthophosphate dikinase by ADP-/Pi-dependent reversible phosphorylation in C3 and C4 plants. Plant Physiol. Biochem. 41: 523-532.<br /> <br /> Chollet R, Spreitzer RJ, Eds. (2003) The C-fixing enzymes in plants. Arch. Biochem. Biophys. 414: 129-222. [an invited Highlight Section in the June 15th issue]<br /> <br /> Crevillén P, Ballicora MA, Mérida Á, Preiss J, Romero J. (2003) The different large subunit isoforms of Arabidopsis thaliana ADP-glucose pyrophosphorylase confer distinct kinetic and regulatory properties to the heterotetrameric enzyme. J. Biol. Chem. 278: 28508-2515. <br /> <br /> Cushman JC (2003a) C3 photosynthesis to Crassulacean acid metabolism shift in Mesembryanthemum crystallinum: A stress tolerance mechanism. Encyclo. Plant Crop Sci. In press. [Invited review].<br /> <br /> Cushman JC (2003b) Functional Genomics of Plant Abiotic Stress Tolerance. In: Genomics of Plants and Fungi. Ed. R.A. Prade and H.J. Bohnert. Marcel Dekker, Inc. New York, NY. 18: 315-357. [Invited review].<br /> <br /> Danner BT, Knapp AK. (2003) Abiotic constraints on the establishment of Quercus seedlings in grassland. Global Change Biology 9: 266-275. <br /> <br /> Devillirs CH, Piper ME, Ballicora MA, Preiss J. (2003) Characterization of the branching patterns of glycogen branching enzyme truncated on the N-terminus. Arch. Biochem. Biophys. 418: 34-38.<br /> <br /> Dodd AN, Griffiths H, Taybi T, Cushman JC, Borland AM. (2003) Integrating diel starch metabolism with the circadian and environmental regulation of Crassulacean acid metabolism in Mesembryanthemum crystallinum. Planta 216: 789-797<br /> <br /> Du YC, Peddi SR, Spreitzer RJ. (2003) Assessment of structural and functional divergence far from the large-subunit active site of ribulose-1,5-bisphosphate carboxylase/ oxygenase. J. Biol. Chem. (in press).<br /> <br /> Edwards GE, Franceschi VR, Voznesenskaya EV. (2004) Single cell C4 photosynthesis. Annual Review of Plant Biology. Invited review. In press.<br /> <br /> Ermolova NV, Cushman MA, Taybi T, Condon SA, Cushman JC, Chollet R (2003) Expression, purification, and initial characterization of a recombinant form of plant PEP-carboxylase kinase from CAM-induced Mesembryanthemum crystallinum with enhanced solubility in Escherichia coli. Protein Express Purific. 29:123-131. [collaborative regional research between NE-AES and NV-AES].<br /> <br /> Fay PA, Carlisle JD, Knapp AK, Blair JM, Collins SL. (2003) Productivity responses to altered rainfall patterns in a C4-dominated grassland. Oecologia 137: 245-251. <br /> <br /> Freuauf JB, Ballicora MA, Preiss J. (2003) ADP-glucose Pyrophosphorylase from potato tuber. Site-Directed Mutagenesis of Homologous Aspartic Acid Residues in the Small and Large Subunits. Plant J. 33: 503-511.<br /> <br /> Gao Z, Maurousset L, Lemoine R, Yoo S-D, van Nocker S, Loescher W. (2003) Cloning, expression, and characterization of sorbitol transporters from developing sour cherry (Prunus cerasus) fruit and leaf sink tissues. Plant Physiol 131: 1566-1575.<br /> <br /> Gao Z, Loescher WH. (2003) Expression of a celery mannose 6-phosphate reductase in Arabidopsis thaliana enhances salt tolerance and induces biosynthesis of both mannitol and a glucosyl-mannitol dimer. Plant Cell and Environment 26: 275-283<br /> <br /> Gao Z, Jayanty S, Beaudry R, Loescher W. (2003) Watercore and sorbitol transporters in apple fruit. HortScience 38:863 abstract.<br /> <br /> Gehrig HH, Aranda J, Cushman MA, Virgo A, Cushman JC, Hammel BE, Winter K. (2003) Cladogram of Panamanian Clusia based on nuclear DNA: Implications for the origins of Crassulacean Acid Metabolism. Plant Biol. 5:59-70.<br /> <br /> Gibson KM, Hwang S-K, Edwards GE, Okita TW, Kato C, Mitsui H, Ito H. (2003) Metabolic engineering of starch for enhanced plant productivity and yields. J. Appl. Glycosci. 50: 201-205.<br /> <br /> Hardin SC, Tang G-Q., Scholz A, Holtgraewe D, Winter H, Huber SC. (2003) Phosphorylation of sucrose synthase at serine-170: occurrence and possible role as a signal for proteolysis. Plant J. 35: 588-603.<br /> <br /> Hardin SC, Huber SC. (2003) Proteasome activity and the post-translational control of sucrose synthase stability in maize leaves. Plant Physiol. Biochem. In press.<br /> <br /> Heng-Moss T, Mni X, Macedo T, Markwell JP, Baxendale FP, Quisenberry SS, Tolmay V. (2003) Comparison of chlorophyll and carotenoid concentrations among Russian wheat aphid (Homoptera: Aphididae)-infested wheat isolines. J. Econ. Entomol. 96: 475-481.<br /> <br /> Houtz RL, Portis AR Jr. (2003) The life of ribulose 1,5-bisphosphate carboxylase/oxygenase  posttranslational facts and mysteries. Arch. Biochem. Biophys. 414: 150-158.<br /> <br /> Knapp AK, Fay PA, Blair JM, Collins SL,. Smith MD, Carlisle JD, Harper CW, Danner BT, Lett MS, McCarron JK. (2002) Rainfall variability, carbon cycling and plant species diversity in a mesic grassland. Science 298: 2202-2205.<br /> <br /> Koch KE (2004) Sucrose breakdown: Dual role in C-use and sugar signals. Curr. Op. Plant Biol. 7: 5-13<br /> <br /> Kramer DM, Johnson G, Kiirats O, Edwards GE. (2003) New fluorescence parameters for the determination of excitation energy fluxes in connected photosystems. Photosynthesis Research. In press.<br /> <br /> Kramer DM, Ivanov B, Edwards GE, Kanazawa A, Cruz JA. (2003) The relationship between photosynthetic electron transfer and its regulation. Review: Advances in Photosynthesis. In press.<br /> <br /> Loescher WH. (2003) Cherries. Encyclopedia of Food Sciences and Nutrition, 2nd Ed. Academic Press, London. <br /> <br /> Lonosky P, Zhang X, Honavar V, Dobbs D, Fu A, Rodermel S. (2003) A proteomic analysis of maize chloroplast biogenesis. Plant Physiology (in press).<br /> <br /> Mao C, Cushman JC, May G, Weller JW (2003) ESTAP-an automated system for the analysis of EST data. Bioinformatics. 19:1720-1722.<br /> <br /> Mazarei M, Puthoff DP, Hart JK, Rodermel SR, Baum TJ. (2002) Identification and characterization of a soybean ethylene-responsive element-binding protein gene whose mRNA expression changes during soybean cyst nematode infection. Molecular Plant-Microbe Interactions 15: 577-586.<br /> <br /> Mazarei M, Lennon KA, Puthoff DP, Rodermel SR, Baum TJ. (2003). Expression of an Arabidopsis phosphoglycerate mutase homologue is localized to apical meristems, regulated by hormones, and induced by sedentary plant-parasitic nematodes. Plant Mol. Biol. (in press) <br /> <br /> Moore B. (2003) Bifunctional and moonlighting proteins: efficacious solutions to lifes problems. (Submitted)<br /> <br /> Moore B, Zhou L, Rolland F, Hall Q, Cheng W-H, Liu Y-X, Hwang I, Jones T, Sheen J. (2003) Role of the Arabidopsis glucose sensor HXK1 in nutrient, light, and hormonal signaling. Science 300: 332-336.<br /> <br /> Okita TW, Sakulsingharoj C, Choi S-B, Ogawa M, Singh S, Gupta HS, Bork J, Meyer CR, Edwards GE, Preiss J. (2003) Metabolic engineering starch and protein biosynthesis in developing rice seeds. Proceedings of the International Conference BioThailand 2003: Technology for Life. BIOTEC, PEACH, Pattaya, Thailand.<br /> <br /> Portis AR. Jr. (2003) Rubisco activase  Rubiscos catalytic chaperone. Photosynth. Res. 75:11-27.<br /> <br /> Portis AR. Jr. (2004) Rubisco Activase. Encyclopedia of Plant and Crop Science. R.M. Goodman, ed. Marcel Dekker, Inc.<br /> <br /> Puthoff DP, Nettleton D, Rodermel SR, Baum TJ. (2003) Arabidopsis gene expression changes during cyst nematode parasitism revealed by statistical analyses of microarray expression profiles. Plant Journal 33: 1-11.<br /> <br /> Ramberg HA, Olson BJSC, Nishio JN, Markwell J, Osterman JC. (2002) The role of methanol in promoting plant growth: an update. Rev. Plant Biochem. Biotechnol. 1: 113-126.<br /> <br /> Rodermel S. (2002) Regulation of Photosynthesis. Plant Science 162: 1019-1021. [Invited book review].<br /> <br /> Rizhsky L, Hallak-Herr E, Van Breusegem F, Rachmilevitch S, Barr J, Rodermel S, Inze D, Mittler R. (2002) Double antisense plants lacking ascorbate peroxidase and catalase are less sensitive to oxidative stress than single antisense plants lacking ascorbate peroxidase or catalase. Plant Journal 32: 329-342. <br /> <br /> Rodermel S. (2002) Redesigning Rice Photosynthesis to Increase Yield Crop Science 42: 3-4. [Invited book review].<br /> <br /> Rodermel S, Park S. (2003) Pathways of intracellular communication: tetrapyrroles and plastid-to-nucleus signaling. BioEssays 25: 631-636. <br /> <br /> Roychaudhuri R, Sarath G, Zeece M, Markwell J. (2003) Reversible denaturation of the soybean Kunitz trypsin inhibitor. Arch. Biochem. Biophys. 412: 20-26.<br /> <br /> Sakulsingharoj C, Choi S-B, Okita TW. (2003) Manipulation of ADP-glucose pyrophosphorylase in starch biosynthesis during rice seed development. In "Rice Genetics IV. Proceedings of the Fourth International Rice Genetics Symposium" International Rice Research Institute, Rice Genetics III, P.O. Box 933, Manila, Philippines. In Press.<br /> <br /> Satoh H, Nishi A, Fujita N, Kubo A, Nakamura Y, Kawasaki T, Okita TW. (2003) Isolation and Characterization of Starch Mutants in Rice. J. Applied Glycoscience. 50:225-230.<br /> <br /> Singh S, Slattery, Choi SB, Okita TW. (2003) Molecular cloning, expression, kinetics and regulatory properties of ADP-glucose pyrophosphorylase from chickpea. Plant Physiol. Biochem. 41:399-405.<br /> <br /> Sakulsingharoj C, Choi SB, Ogawa M, Singh S, Bork J, Meyer CR, Edwards GE, Preiss J, Okita TW (2003) Manipulating starch and storage protein biosynthesis during endosperm development to increase rice yield. Proceedings of the 24th International Rice Research Conference, International Rice Research Institute, In Press.<br /> <br /> Shen W, Clark AC, Huber SC. (2003) The C-terminal tail of Arabidopsis 14-3-3 omega functions as an autoinhibitor and may contain a tenth alpha-helix. Plant J. 34: 473-484.<br /> <br /> Soulages JL, Kim K, Arrese EL, Walters C, Cushman JC (2003) Conformation of a Group 2 Late Embryogenesis Abundant (LEA) Protein from Soybean: Evidence of Poly (L-Proline)-type II (PII) Structure. Plant Physiol. 131:963-975.<br /> <br /> Spreitzer RJ. (2003) Role of the Rubisco small subunit. Arch. Biochem. Biophys. 414: 141-149.<br /> <br /> Stessman D, Miller A, Spalding M, Rodermel S. (2002) Regulation of photosynthesis during Arabidopsis leaf development in continuous light. Photosynthesis Research 72: 27-37.<br /> <br /> Szurmak B, Mooney BP, Miernyk JA, Randall DD. (2003) Expression and assembly of Arabidopsis thaliana pyruvate dehydrogenase in insect cell cytoplasm. Prot. Purif. & Express. 28:357-361<br /> <br /> Tang G-Q, Hardin SC, Dewey R, Huber SC. (2003) A novel C-terminal proteolytic processing of cytosolic pyruvate kinase, its phosphorylation and degradation by the proteosome in developing soybean seeds. Plant J. 34: 77-95.<br /> <br /> Tovar-Mendez A, Miernyk JA, Randall DD. (2002) Histidine mutagenesis of Arabidopsis thaliana pyruvate dehydrogenase kinase. Eur.J. Biochem. 269: 2601-2606. <br /> <br /> Tovar-Mendez A, Miernyk JA, Randall DD (2003) Regulation of pyruvate dehydrogenase complex activity in plant cells. Eur. J. Biochem. 270: 1043-1049. <br /> <br /> Voznesenskaya EV, GE Edwards, O Kiirats, EG Artyusheva, VR Franceschi. (2003) Development of biochemical specialization and organelle partitioning in the single celled C4 system in leaves of Borszczowia aralocaspica (Chenopododiaceae). Am. J. Bot. In press.<br /> <br /> Voznesenskaya, EV, VR Franceschi, EG Artyusheva, CC Black, VI Pyankov and GE Edwards. (2003) Development of the C4 photosynthetic apparatus in cotyledons and leaves of Salsola richteri (Chenopodiaceae). Int. J. Plant Sci. 164: 471-487.<br /> <br /> Voznesenskaya EV, VR Francheschi, GE Edwards. Light dependent development of single cell C4 photosynthesis in cotyledons of Borszczowia aralocaspica (Chenopodiaceae) during transformation from a storage to a photosynthetic organ. Annals of Botany. In press.<br /> <br /> Wachter R, Langhans M, Aloni R, Gotz S, Weilmunster A, Koops A, Temguia L, Mistrik I, Pavlovkin J, Rascher U, Schwalm K, Koch KE, Ulrich CI. (2003) Vascularization, high-volume solution flow, and localized roles for enzymes of sucrose metabolism during tumorigenesis by Agrobacterium tumefaciens. Plant Physiology (In Press)<br /> <br /> Walker D, Edwards G. (2004) Photosynthetic Carbon Assimilation. In: Molecular to Global Photosynthesis. Eds. MD Archer and J Barber. Invited chapter. In press.<br /> <br /> Xu W, Zhou Y, Chollet R. (2003) Identification and expression of a soybean nodule-enhanced PEP-carboxylase kinase gene (NE-PpcK) that shows striking up-/down-regulation in vivo. Plant J. 34: 441-452.<br /> <br /> Yep A, Bejar CM, Ballicora MA, Dubay J, Iglesias AA, Preiss J. (2003) An assay for the ADP-glucose Pyrophosphorylase that measures the synthesis of radioactive ADP-glucose with glycogen synthase. Analytical Biochemistry. In Press.<br /> <br /> Yoo S-D, Gao ., Cantini C, Loescher W, van Nocker S. (2003) Fruit ripening in sour cherry (Prunus cerasus): changes in expression of genes expressing expansins and other cell-wall-modifying enzymes. J Amer Soc Hort Sci 128: 16-22.<br /> <br /> Yu F, Park S, Rodermel SR. (2003) The Arabidopsis FtsH metalloprotease gene family: interchangeability of subunits in chloroplast oligomeric complexes. Plant Journal (in press). <br /> <br /> Yao Y, Guiltinan MJ, Shannon JC, Thompson DB. (2003) Single kernel sampling method for maize starch analysis while maintaining kernel vitality. Cereal Chem. 79: 757762.<br /> <br /> Zeng Y, Koch KE (2002) Molecular approaches to altered C partitioning: Genes for sucrose use. Jour. Amer. Soc. Hort. Sci. 127: 474-483<br /> <br /> Zheng P, Wetzel C, Ammar K, Girard A-M, Rodermel S, Thomas DR, Ning L, Callis JB, Edwards GE, Daley L. (2002) Test of an in vivo method to detect chloroplast division in crop plants. Part I: Discovery of the phenomenon. Spectroscopy 17: 16-25.<br /> <br /> Zheng P, Wetzel C, Ammar K, Girard A-M, Rodermel S, Thomas DR, Ning L, Callis JB, Edwards GE, Daley L. (2002). Test of an in vivo method to detect chloroplast division in crop plants. Part II: Verification of the phenomenon by germplasm methods and confocal microscopy. Spectroscopy 17: 14-18.<br /> <br /> Zhu X-G, Portis AR Jr., Long SP. (2004) Would transformation of C3 crop plants with Foreign Rubisco increase productivity? A computational analysis extrapolating from kinetic properties to canopy photosynthesis. Plant Cell Environ., in press.<br />

Impact Statements

1. Several key genes in the process of plastid biogenesis have been identified and their function understood at the molecular genetic. These genes are key players in thylakoid membrane biogenesis and oxidative stress adaptation and carotenoid biosynthesis. These discoveries will lead to novel strategies to manipulate photosynthetic capacity and quality traits, such as fruit color, in important crop species.
2. Investigations into the role of Rubisco activase in relieving the inhibition of Rubisco activity at high temperatures suggests that activase may be a useful target for improving the performance of photosynthesis in crop plants at elevated temperatures.
3. Modeling studies predict that very substantial increases (>25%) in crop carbon gain could result if specific Rubiscos having either a higher specificity for CO2 relative to O2 or higher turnover rate for carboxylation can be successfully expressed in C3 plants.
4. Insights into regulatory mechanism of carbon partitioning will be facilitated by understanding how the mitochondrial pyruvate dehydrogenase complex is regulated by reversible phosphorylation events and will allow identification of metabolites that contribute to the regulation of photosynthesis and photorespiration.
5. Soluble invertases play a key role during early kernel development, and recent developments indicate this may include close integration with ABA and sugar signals both of which are critical to adjustment of reproductive load that is crucial to yield and survival of offspring.
6. Fundamental studies of the biochemical mechanisms that control critical plant processes such as sucrose metabolism, nitrate assimilation, and assimilate transport, will directly contribute to our ability to increase the capacity of crop plants to produce nutrients (sugars and amino acids) that support growth of harvested plant parts used for food and fiber.
7. Soil salinity equivalent to ~40 mM NaCl buildup in U.S. Crop land toxic to many crops. Increased salinity tolerance was achieved by genetic modifications to produce low levels of mannitol using a celeray gene to increase tolerance equivalent to irrigation water containing ~20 and 40% of seawater illustrating the potential for increased tolerance to salinity by engineering plants.
8. In studies with Arabidopsis transformants expressing up-regulated forms of ADP-glucose pyrophosphorylase, the committed step in starch biosynthesis, there is potential for increasing the capacity for starch biosynthesis, and alleviating inhibition of photosynthesis by feedback where there is insufficient capacity to use photosynthetic products.
9. The elucidation of glycogen synthase structure/function may provide information useful in the studies of the starch synthase an enzyme homologous to the bacterial glycogen synthase for modifying starch structure in vivo, for different commercial functional purposes, eg., in the development of new plastics.
10. The expression or over-expression of cytokinin synthesis genes in specific kernel component tissues may be a viable molecular approach to increasing endogenous cytokinin levels during kernel development and thus stabilizing grain yield of maize against the periodic occurrence of heat stress or more long-term global climate change.
11. Projected climate changes represent a significant threat to grassland structure and function. Identifying and understanding limitations to photosynthesis and productivity in the dominant grasses in this ecosystem has tremendous economic importance regionally.
12. Identifying trait differentiation between cold and heat tolerant and susceptible lines, and associating differences with position on the sorghum genome would contribute to knowledge of thermotolerance and may guide subsequent germplasm development. The increased yield potential of early-planted hybrids with longer grain-fill duration would boost crop and land productivity. The annual economic impact in Kansas could exceed $65 M.

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Report Information

Participants

Fred Below (IL-AES), Hans Bohnert (IL-AES), Ray Chollet (NE-AES), John Cushman (NV-AES), Larry Daley (OR-AES), Stan Duke (WI-AES), Gerald Edwards (WA-AES), Mark Guiltinan PA-AES), Jeff Harper (NV-AES), Robert Houtz (KY-AES), S.C. Huber (IL-ARS, Urbana), Robert Jones (MN-AES), Allen D. Knapp (IA-AES), Al K. Knapp (KS-AES), Karen Koch (FL-AES), Wayne Loescher (MI -AES), Steve Long (IL-AES), John Markwell (NE-AES), Thomas Marler (GuamAES), Ron Mittler (NV-AES), Brandon Moore (SC-AES), Tom Okita (WA-AES), Archie Portis (IL-ARS, Urbana), Jack Preiss (MI-AES), Doug Randall (MO-AES), Steve Rodermel (IA-AES), Robert Spreitzer (NE-AES).

Brief Summary of Minutes

Annual Meeting Date and Location:
November 12-13, 2004
South Carolina AES host,
Hyatt Regency Hotel, Greenville, SC

Attending Members:
Dr. Karen Koch Florida AES
Dr. Robert Aiken Kansas AES
Dr. Robert Houtz Kentucky AES
Dr. Steve Long Illinois AES
Dr. Steve Rodermel Iowa AES
Dr. Jack Preiss Michigan AES
Dr. Robert Spreitzer Nebraska AES
Dr. Jeff Harper Nevada AES
Dr. Larry Daley Oregon AES
Dr. Brandon Moore South Carolina AES
Dr. Forrest Chumley Admin. Advisor, Kansas AES

Attending Guests Interested in NC-1-142 Membership:
Dr. Robert Aiken Kansas AES
Dr. Michael Salvucci Arizona USDA-ARS
Dr. Jyan-Chyun Jang Ohio AES
Dr. Glenda Gillaspy Virginia AES

This year's meeting was called to order by Dr. Brandon Moore, Chair. Scientific discussions began during the previous evening among members present and continued during breaks, lunch, and later at dinner. Participants each gave a 25 min overview of their previous years accomplishments, with questions and comments following their presentation. The talks included also a group discussion with our Administrative Advisor, Dr. Forrest Chumley.

Dr. Chumley complemented the NC-1-142 members on the quality of their science, and the positive interaction between members. He indicated that NC-1-142 as a regional project is known for the high caliber of research by its members, and pointed out that NC-1-142 is essentially a regional project that extends across the entire country. Dr. Chumley noted, however, that the time-frame of the meeting left little time for interactions given the number of presentations and the limit to two days (Friday-Saturday). He suggested that the members consider extending the meeting time to three days (Friday-Sunday) so that more exchange and interaction between members could occur outside the framework of formal research presentations. He noted there is also an upcoming mid-project review to be considered in the near future. There was general agreement from the members that a more work-shop style approach should be considered for future meetings. Dr. Chumley also pointed out that it might be advantageous to consider a more geographically central location for the meetings, since this would help with travel time and there are members on both coasts. Dr. Chumley also addressed a previous suggestion at the last meeting that membership and attendance should be linked. Dr. Chumley pointed out that while many members receive financial support from their home institutions experiment station, this is not true for all members. Thus, travel costs for some are the individuals responsibility. The members were appreciative of Dr. Chumleys comments and presence at the meeting.

Most discussion addressed Objectives 2, 3, and 4, which respectively are Photosynthetic Capture and Photorespiratory Release of CO2,Mechanisms Regulating Photosynthate Partitioning and Developmental and Environmental Limitations to Photosynthesis. Each of these objectives was well represented by the attendees at this year's meeting, but all members were involved in general discussion of the presentations.

The business meeting was called to order after the talks. The meeting was attended by all members listed and lasted about 30 min. The primary issues were to 1) discuss candidates for incoming membership, 2) elect new officers, and 3) further consider our discussion with Dr. Chumley. The Chair noted that several previous members had resigned this year from the group and most members agreed that recruitment of strong new members is important to the vitality of the project. Four guests were considered for membership in NC-1-142, Robert Aiken, Michael Salvucci, Jyan-Chyun Jang, and Glenda Gillaspy. In addition to their oral presentations, all had provided the group with a c.v. and a statement of research interests as related to the NC-1-142 project. After some discussion including submitted comments from members not in attendance, a motion was made and seconded to extend membership to all four candidates. The motion was unanimously approved.

New officers were selected with Dr. Karen Koch as Chair and host for the 2005 meeting, Dr. Robert L. Houtz as vice-chair, and Dr. Robert Spreitzer as secretary. The group agreed to maintain the current relative meeting date, 2 weekends before Thanksgiving. At the discretion of the new chair, next years meeting format might be altered along lines suggested by Dr. Chumley.

Key discussions at the meeting:
These centered on the science outlined in reports from the attending AES/ARS representatives, the visiting candidates for new membership, and the comments by Dr. Chumley. The primary issues of the business meeting are enumerated above.

Assigned responsibilities:
As decided by NC-1-142 participants, the leadership succession will progress from Dr. Brandon Moore (South Carolina AES) departing Chair of the 2004 meeting, to Dr. Karen Koch (Florida AES) incoming Chair and host for the 2005 meeting. Dr. Robert Houtz will become vice-chair and will host the 2006 meeting. Dr. Robert Spreitzer will serve as secretary for the 2005 meeting. As noted above, the weekend selected for the 2005 meeting again will be ONE WEEK EARLIER than in past years, now two weekends prior to the Thanksgiving holiday. The date will be November 11-13, 2005.

Accomplishments

Photosynthesis is the fundamental process that enables the synthesis of sugars and all other biomolecules required for plant growth. Photosynthesis uniquely integrates light photochemistry, biochemical fixation of atmospheric carbon dioxide, and the utilization of inorganic nutrients to sustain and direct crop production under a variety of environmental conditions. This regional research project is an integrated cooperative program in which the expertise of AES and ARS investigators is applied to four aspects of the photosynthetic process.<br /> <br /> Objective 1: Photochemistry and the biogenesis of the photosynthetic apparatus<br /> Cooperating AES and/or ARS-USDA:<br /> IA (Rodermel).<br /> <br /> The molecular and biochemical coordination between nuclear and plastid gene expression continues as a major research focus by IA-AES (Rodermel), in which they are exploiting a number of available variegated plant mutants with green- and white-sectored leaves. These are proving useful to understanding chloroplast biogenesis, which is deficient in white sectored-leaves. For example, the GHOST variegation mutant of tomato was found to encode a chloroplast quinol oxidase that affects the biogenesis of chloroplasts and chromoplasts, as well as pericarp tissue morphogenesis, during the ripening process. Mutations in certain Arabidopsis chloroplast metalloproteases, FtsH5 (var1) and FtsH2 (var2), give rise to white sectors likely through a compromised post-transcriptional regulatory process. To gain further insight to the mechanism, a suppressor screen of var2 yielded several normal appearing lines. Map-based cloning revealed that suppression of variegation in one line is due to a splice site mutation in ClpC2, a chloroplast Hsp 100 chaperone. Further insight into the function of var2 in photosynthesis, plant development and plant stress responses might lead to the design of strategies to manipulate the photosynthetic capacity and quality of crop plants.<br /> <br /> Objective 2: Photosynthetic capture and photorespiratory release of CO2<br /> Cooperating AES and/or ARS-USDA:<br /> IL (Portis), KY (Houtz), MO (Randall), NE (Chollet, Spreitzer), NV (Cushman),WA (Edwards, Okita).<br /> <br /> IL-ARS (Portis) has done experiments to better define the interactions between Rubisco and activase, their role in the inhibition of photosynthesis by high temperatures, and to develop alternative strategies for genetic engineering of Rubisco. A long-term collaboration with NE-AES (R. Spreitzer) uses chimeric spinach-tobacco activase proteins and site-directed mutagenesis to determine the specificity of activase for Solanaceae versus non-Solanaceae Rubiscos. In the current period, they showed that amino acids in the 267-339 region are responsible for Rubisco discrimination by tobacco activase, with residue 311 playing a major role. The Portis lab also showed that as temperature increases, Rubisco activity declines rapidly and certain inhibitors from the oxygenase reaction are formed more rapidly, but bind less tightly. Understanding activase function at high temperature will be important for crop improvement. Lastly, in collaboration with Dr. Henry Daniells laboratory (Univ. of Central Florida), in an exciting result, transgenic tobacco plants were made by chloroplast transformation of nuclear rbcS into an rbcS anti-sense plant. Progeny expressed mRNA from the introduced gene at high levels in the chloroplast, expressed Rubisco at almost the original wildtype level, and exhibited nearly restored photosynthesis rates. These results have opened an avenue for using chloroplast engineering for the evaluation of foreign Rubisco genes in planta. <br /> <br /> Studies at NE-AES (Spreitzer) continue to exploit Chlamydomonas rheinhardtii as a model system to use classical and molecular genetic strategies to define structure-function relations of Rubisco, with an overall goal to create a catalytically improved protein. Contemporary research has shown that this goal does require an in-depth understanding of these relationships. In an ongoing collaboration with Dr. Inger Andersson (Swedish Agricultural University, Uppsala), X-ray crystal structures have now been solved for more than 12 mutant Rubisco enzymes. Analysis of these has revealed novel insights and in some cases have shown that specific amino acids can have multiple functions. For example, the active-site Lys-175 was found to have an essential role in both catalysis and in vivo holoenzyme stability. Another finding was that the L290F mutant enzyme has a low CO2/O2 specificity and does not form a key H-bond with a substrate analog. Interestingly, this H-bond is restored in a L290F/A222T suppressor mutant. Since more than 2000 rbcL sequences are now available, bioinformatics approaches also are being used to define the structural basis for catalytic diversity among organisms. Making phylogenetic directed mutations has revealed novel properties at the small and large subunit interface that modulate catalytic properties and warrant further examination as possible targets for genetic engineering.<br /> <br /> Ongoing research at NE-AES (Chollet) has focused on the characterization and regulation of phosphoenolpyruvate (PEP) carboxylase isoforms in green algae, leaves and root nodules. In the current period, they have identified two novel PEPC genes in C. reinhardtii. These both lack an N-terminal phosphorylation domain present in green plant PEPC, yet characteristically are absent in prokaryotic PEPCs. Both genes were cloned and expressed in E. coli, and transcript abundance and biochemical activity were characterized. Work also was reported on the role of the C-terminal tetrapeptide in catalysis by sorghum PEPC. Site-directed mutagenesis on G961 showed this residue is critical for catalytic efficiency, but a G961A substitution was able to complement a related E. coli mutant. <br /> <br /> The Houtz laboratory (KY-AES) is characterizing chloroplast-localized post- and co-translational protein processing enzymes with emphasis on the large (LS) and small (SS) subunits of Rubisco. In Rubisco, a conserved amino acid sequence in the N-terminal region of the LS from Ala-9 to Lys-14 establishes the specificity for methylation at Lys-14. This region fits into a narrow cleft in Rubisco LS eN-methyltransferase (LSMT). Proof of principle was shown also by making an alternate substrate for Rubisco LSMT after fusing the N-terminal sequence from the LS to the N-termini of human carbonic anhydrase. In a separate project, possible cotranslational chloroplast protein processing by deformylases has been further examined. Deformylases DEF1 and DEF2 were shown to be targets of the inhibitor actinonin. This peptidomimetic antibiotic is known to inhibit chloroplast D1 polypeptide levels, leading to a disassembly of the photosystem II complex. The results confirm that N-terminal deformylation is an essential step in the accumulation and assembly of PSII subunit polypeptides in the chloroplasts of vascular plants.<br /> <br /> The mitochondrial pyruvate dehydrogenase complex (mtPDC) links glycolysis to the Krebs cycle by catalyzing the oxidative decarboxylation of pyruvate to acetyl-CoA. MO-AES (Randall) continues to examine the reversible phosphorylation of mtPDC, which provides the cardinal regulatory mechanism for the interaction of respiratory and photorespiratory metabolism. The protein kinase that phosphorylates mtPDC is a novel Ser-protein kinase, which they have now shown is a unique type of protein kinase that has a His-kinase like sequence, but Ser-kinase activity. Details of the phosphorylation mechanism have been better defined by kinase site directed mutagenesis, demonstrating residues critical for formation of the substrate ternary complex. A recombinant in vitro system also was developed to demonstrate that plant mtPDC has only one regulatory phosphorylation site on E1, unlike mammalian PDC. A reverse genetics approach has begun to establish permissible knockout lines of Arabidopsis PDK and PDC subunits. PDK and E1 knockout lines are being selected for homozygosity.<br /> <br /> NV-AES (Cushman) has continued study of the common ice plant, Mesembryanthemum crystallinum as a model for understanding Crassulacean acid metabolism (CAM). Using a molecular genetic approach, they characterized 9,733 expressed sequence tags (ESTs) from cDNAs derived from leaf tissues of well-watered and salinity-stressed plants. From these, 3,676 tentative unique gene sequences allowed rapid discovery of both known and unknown genes related to CAM induction and salinity tolerance in M. crystallinum. For example, the frequency of ESTs encoding light-harvesting and photosystem complexes and C3 photosynthetic enzymes decreased four- to seven-fold following salinity stress, while transcripts encoding CAM-related enzymes, pathogenesis-related, senescence-associated, cell death-related, and stress-related proteins such as heat shock proteins, chaperones, early light-inducible proteins, ion homeostasis, antioxidative stress, detoxification, and biosynthetic enzymes for osmoprotectants increased 2-12-fold in salt stressed plants. In a separate project, the Cushman lab has examined many of the molecular components and their transcript expression in relation to circadian clock function in M. crystallinum. While some differences were noted in the diurnal expression profiles of particular components when compared to Arabidopsis, the clock in M. crystallinum likely functions in a very similar fashion to the clock in Arabidopsis. This indicates that such a clock could control CAM without requiring additional components of the central oscillator.<br /> <br /> Objective 3: Mechanisms regulating photosynthate partitioning<br /> Cooperating AES and/or ARS-USDA:<br /> FL (Koch), IA (Knapp, Rodermel), IL (Bohnert, Huber), MI (Preiss, Loescher),NE (Chollet), NV (Harper), PA (Guiltinan), SC (Moore), WA (Edwards, Okita),WI (Duke).<br /> <br /> FL-AES (Koch) has examined the response of an Arabidopsis vacuolar invertase gene family to sugar and ABA. Since sucrose is the major carbon and energy source for most importing plant cells, effects of plant invertases on hexose/sucrose balance can markedly alter expression of diverse, sugar-regulated genes. In Arabidopsis, there are two vacuolar invertase genes, plus six cell wall invertase genes. In the current period, methods were developed for quantitative Q-RT-PCR and gene-specific amplicons for each family member. Tissue specific gene expression and gene-specific regulatory effects of sugar and ABA were demonstrated. These contrasting responses provide a mechanism for maximizing flexibility and balance at a key point in both sucrose metabolism and sugar/ABA signaling. Effects of knock-outs in these invertases is also being investigated in conjunction with IA-AES (S. Rodermel). The Koch lab also has been involved in identifying and characterizing maize knockout mutants. For example, vegetative phenotypes were examined for maize mutants lacking one or two sucrose synthases. Differential and additive affects were noted, especially with regard to seed weight and germination. To identify further maize knockout mutants, reverse-genetics grids are being constructed using a phenotypically uniform inbred population (UniformMu). Initial screening is in progress for knockouts in key genes for cell wall biosynthesis.<br /> <br /> IL-ARS (Huber) has done novel experiments probing the control of plant metabolism by protein phosphorylation. In one approach, far-Western overlays of extracts prepared from light- or dark-treated spinach (Spinacia oleracea) leaves were used to identify factors that affected binding of cellular proteins to labeled 14-3-3 protein. Binding of phosphorylated proteins was shown to be stimulated by polycations, but specificities were not notably affected. Using recently obtained modification-specific antibodies, IL-ARS has begun to monitor the phosphorylation status of nitrate reductase (NR) in Arabidopsis leaves by immunoblotting. In collaboration with Dr. Mike Sussman (UW-Madison), they are screening CDPK-knockout lines to identify the requisite NR-kinase(s). Also important will be identifying the factors that 'trigger' the release of bound 14-3-3 protein and thereby the activation and dephosphorylation of NR. In conjunction with FL-AES (K. Koch), IL-ARS also is characterizing stable maize transgenics that express wild type and phosphorylation site mutants of the SUS1 (sucrose synthase) protein. To aid these studies, they have obtained antibodies that specifically detect the SUS3 protein, which has not been previously characterized at the protein level. In collaboration with SC-AES (B. Moore), IL-ARS has initiated a new project to determine whether HXK-mediated glucose signaling is affected by nitric oxide (NO). It is known that glucose inhibition of Arabidopsis seedling growth and greening can be antagonized by nitrate. This effect may be mediated by NO (known to be generated by reduction of nitrite by NR), because HXK1 contains 3 cysteine residues in a consensus motif predicted to be susceptible to S-nitrosylation.<br /> <br /> MI-AES (Preiss) have done studies to determine structure-function aspects of both the ADPglucose pyrophosphorylase (AGP) and glycoge synthase. AGP catalyzes the first committed and rate-limiting step in starch biosynthesis in plants and glycogen synthase similarly for glycogen biosynthesis in bacteria. They are the master regulators of storage polysaccharide accumulation in plants and bacteria, being allosterically activated or repressed by metabolites of energy flux. In a significant development, they report the first atomic resolution structure of an AGP crystallized from potato tuber. Communication between the regulator binding sites and the active site of AGP are both subtle and complex, and involve several distinct regions of the enzyme including the N-terminus, the glucose-1-phosphate binding site and the ATP binding site. These structures provide insights into the mechanism for catalysis and allosteric regulation of AGP. MI-AES also modeled the E. coli glycogen synthase catalytic site based on three glycosyltransferases with a GT-B fold. The model was validated after analysis of targeted site-directed mutants which had predictable effects on reaction kinetic constants. <br /> <br /> The Harper lab (NV-AES) has just recently joined in the project objective. They have a long-standing research interest in understanding and modifying the transport machinery that moves sucrose and other nutrients from source to sink. The driving force for solute transport across plant cell plasma membranes is a proton gradient produced by a P-type H+-ATPase. Proton pumps are responsible for the driving force underlying sucrose loading and its long distance transport through phloem. Harper was the first to clone a plant proton pump in 1989, and has pursued an active research program to understand the structure and biological functions of these pumps.<br /> <br /> In the past year, SC-AES (Moore) has examined the cellular process by which Arabidopsis hexokinase1 (HXK1) transduces a sugar signal. HXK-dependent glucose signaling affects plant growth throughout the plant life cycle and modulates a number of genes related to carbohydrate synthesis and utilization. Using leaf fractionation and bioimaging of 35S::HXK1-GFP plants, HXK1 was shown to occur exclusively at the mitochondria under varying treatments and in all tissues. Thus, glucose signal transduction might involve mitochondria translocation to or from the nucleus, or might involve a mobile HXK1 interacting protein. A previous proteomics experiment identified vegetative actin associated with leaf HXK1. In collaboration with Dr. Richard Meagher (University of Georgia), these scientists used actin mutants and pharmacological treatments of wildtype plants to demonstrate a key finding that the actin cytoskeleton has a direct role in HXK1-dependent glucose signaling. In collaboration with IL-ARS (S. Huber), they have initiated experiments to determine if and to what significance that AtHXK1 might be nitrosylated. Nitric oxide is a recognized intracellular signaling molecule that mediates plant responses to hormones and pathogens. Initial experiments using an HXK1-null mutant and wildtype plants, indicates that HXK1 is required for certain standard seedling responses to NO. Furthermore, HXK1 activity was partly repressed by incubation with an NO donor molecule, thus supporting the possibility that HXK1 is directly modified by NO. <br /> <br /> Research on starch biosynthesis by WA-AES (Edwards and Okita) is directed at understanding its significance in source (leaves) and sink (seed) tissues to photosynthesis, plant growth and crop production. Current work with Arabidopsis has been directed at complementing the TL46, starch-deficient mutant with altered forms of the large subunit of ADP-glucose pyrophos-phorylase (AGP). These forms are less sensitive to inhibition by inorganic phosphate. Transformants have higher AGPase activity and higher starch synthesis than wild type plants. Backcrosses of these up-regulated transformants are being made to select for stable lines with high AGPase activity and starch synthesis. Current work with rice has resulted in the exciting finding that several lines which express potato AGPase exhibit elevated leaf starch levels, higher productivity, and increased yields in field plots at the RDA, Suweon, Korea (in collaboration with Dr. Jong-Sug Park). These results support the view that increases in leaf starch provide, at the minimum, additional carbon and energy reserves during the night, which increase plant growth and development.<br /> <br /> Objective 4: Developmental and environmental limitations to photosynthesis<br /> Cooperating AES and/or ARS-USDA:<br /> Guam (Marler), IL (Below, Bohnert, Long), KS (Knapp), MI (Loescher), MN (Jones),NE (Markwell), NV (Cushman, Harper, Mittler), OR (Daley), WA (Edwards, Okita).<br /> <br /> IL-AES (Below) has examined an important question of how N assimilates move through the young maize earshoot during seed development. To do this, they assessed amino acid metabolism in a 2 year field study, examining cob and spikelet tissues during the critical two weeks following silking. Amino acid profiles and enzyme activities were determined in specific reproductive organs in two maize hybrids grown at two levels of supplemental N fertilizer. Most amino acids except Gln accumulated over time in unpollinated spikelets and cobs, and nitrogen supply had a variable effect on individual amino acid levels in young cobs and spikelets. Interestingly, IL-AES showed that the cob performs significant enzymatic interconversions among Gln, Ala, Asp and Asn during early reproductive development, which may precondition the N assimilate supply for sustained kernel growth. Furthermore, the measured amino acid profiles and enzymatic activities suggest that the Asn/Gln ratio in cobs may be part of a signal transduction pathway that indicates plant N status for kernel development.<br /> <br /> IL-AES (Long) has continued their long-term interests in the acclimation of photosynthesis to global change, primarily the direct effects of rising tropospheric concentrations of CO2 and ozone. A major focus over the past two years has been examining the interactive effects of predicted 2050 levels of ozone and CO2 on soybean (also Arabidopsis) under fully-open air field conditions using the SoyFACE facility. In agreement with the 2003 experiment, their larger scale 2004 FACE experiment has revealed that while rising CO2 increases photosynthesis and yield, the increases even in a nitrogen fixing crop are smaller than anticipated, while the simultaneous increase in ozone results in a substantial yield loss. In the 2004 experiment, a 50% increase in CO2 increased yield by almost 20%, but increased ozone decreased yield by 20%. Ozone decreased photosynthesis, accelerated senescence and crop maturation, and resulted in fewer pods, fewer seeds per pod and smaller seeds. Although not fully analyzed, it is clear that elevation of CO2 partially offsets the damage caused by elevated ozone. However, these results do suggest that the prediction that the detrimental effects of global change in the corn belt may be offset by increases due to rising CO2 may be over-optimistic. IL-AES also has developed improved modeling temperature functions for predicting photosynthesis. These will provide a basis for the development of better mechanistic models of crop responses to global climate change<br /> <br /> KS-AES (Knapp and associates) have pursued studies of plant and ecosystem responses to altered precipitation and temperature. The sensitivity of native grasslands to predicted changes in temperature and rainfall variability poses important questions for the future productivity and sustainability of these ecologically and agriculturally important ecosystems. Results from an ongoing field experiment in which precipitation patterns are being manipulated, indicate that predicted changes in rainfall timing can alter plant processes, from leaf-level photosynthesis to whole plant productivity. In particular, prolonged inter-rainfall droughts during the growing season reduce the potential for recovery of leaf-level photosynthesis once a rewetting rainfall event occurs. KS-AES also showed that plant responses to a more variable rainfall regime could have significant effects on soil processes and ecosystem-level C cycling and storage. Increased temperatures, another prediction of climate change models, may increase plant water stress even further and amplify the effects of increased soil moisture variability. In another project, KS-AES is evaluating photosynthetic performance and thermotolerance in selected recombinant inbred lines of sorghum. The goal is to identify trait differentiation between tolerant and heat-susceptible lines in order to map the relative positions of thermotolerance traits in the sorghum genome. <br /> <br /> MI-AES (Loescher) has collaborated with WA-AES (Edwards, Okita) in studies on salt tolerance using Arabidopsis as a model plant. Arabidopsis transformed with a celery gene for synthesis of mannitol (mannitol 6-P reductase), produces mannitol and has higher growth tolerance to salinity than wildtype Arabidopsis, which does not produce mannitol. In current work, these scientists have shown that transformants were more tolerant to salinity as shown through analysis of photosynthesis and a number of growth parameters. Publication of a joint paper on this work will be forthcoming.<br /> <br /> NE-AES (Markwell) has further examined the kinetics and substrate specificity of Arabidopsis leaf formate dehydrogenase. This enzyme catalyzes the oxidation of formate to CO2 in plant mitochondria. Experiments indicated that anomalous reaction kinetics might be due to a latent capacity for alternate substrate utilization which is realized upon heating. One possibility is that heating generates a molten globule form of the enzyme which upon cooling is able to refold in an alternate conformation that reveals a new substrate binding ability. In the past year, these scientists also have initiated the directed evolution of FDH to obtain variants with increased substrate affinities. A PCR based method of random mutagenesis has been developed and library screening will commence in the following year. NE-AES also has further examined the reversible denaturation of plant proteins, using as a model system the denaturation and renaturation of soybean Kunitz trypsin inhibitor (SKTI). This 21.5-kDa protein is a food allergen, and is unusually resistant to thermal and chemical denaturation. Spectroscopic and biochemical analyses indicated that during denaturation, SKTI shows major structural changes, possibly having formed a molten globule structure as a partially unfolded intermediate.<br /> <br /> NV-AES (Cushman) has further examined the molecular genetic basis for salinity and drought stress limitations on plant photosynthesis. In the past year, they have investigated a salinity- and dehydration-stress responsive calcium-dependent protein kinase (CDPK) isolated from Mesembryanthemum crystallinum (McCPK1). CDPKs are sensor-transducer proteins capable of decoding calcium signals in diverse phosphorylation-dependent calcium signaling networks, including signals generated by environmental stresses. Recombinant McCPK1 was shown to catalyze Ca-dependent substrate phosphorylation, undergo autophosphorylation, and in response to decreased humidity undergo altered sub-cellular localization. In a related project, these scientists have used a series of yeast two-hybrid screens to identify potential substrates of a water deficit- and salt stress-inducible CDPK from Arabidopsis (AtCPK11). Several interacting proteins were identified including likely transcriptional regulators, some of which co-localized in the nucleus with AtCPK11 and showed coordinated up-regulation induced in seedlings by water-deficit stress.<br /> <br /> NV-AES (Harper) also has an important practical goal to identify potential mechanisms to improve crop yield. This includes identifying genes that affect a plants response to biotic and abiotic stresses (including light stress), as well as developmental timing and plant structure. For example, a current project funded in collaboration with J. Cushman and R. Mittler (NV-AES) is to screen Arabidopsis mutants to identify genes that affect a plants ability to grow under extreme environments. These genes will provide important leads in the potential engineering of higher yield crops. In a more global context, it is clear that phospho-signaling provides regulatory switches that affect all aspects of plant growth and response to the environment. The Harper lab has been working on the structure and biological functions of CDPKs since.<br /> <br /> NV-AES (Mittler) is interested in understanding the regulation and function of the plant reactive oxygen gene network. In Arabidopsis, at least 152 genes are involved in managing the level of reactive oxygen species (ROS) in cells and many questions remain unanswered in regard to their regulation and protective roles. In leaf cells, the chloroplast is considered to be a focal point of ROS metabolism. It is a major producer of O2- and H2O2 during photosynthesis and it contains a large array of ROS-scavenging mechanisms that have been extensively studied. In contrast, the function of the cytosolic ROS-scavenging mechanisms of leaf cells is largely unknown. In the past year, NV-AES has used targeted knockout plants to demonstrate that the cytosol has a key role in protecting the chloroplast during light stress. Further work has characterized the signaling events that ensue in response to a moderate level of light stress in plants deficient in this major cytosolic ROS-scavenging mechanism.<br /> <br /> OR-AES (Daley) has pursued examination of the polyphyletic evolution of CAM by considering operational definitions of evolution, development, and manifestation of CAM.<br /> <br /> <br /> Project Participant Plans for 2004-2005<br /> <br /> FL-AES will extend analysis of invertase gene responses and roles in sugar/ABA signaling in knockout mutants of both maize and Arabidopsis (in collaboration with IA-ARS). They also will continue to screen the UniformMu, reverse genetic grids for knockouts in genes of polysaccharide biosynthesis (with preference to cell wall and kernel targets). IA-AES will continue studies to examine the role of VAR2 in photosynthesis by focusing on second-site suppressor studies of var2. IL-ARS will collaborate with NV-AES to identify synthetic peptide inhibitors for CDPKs based on both the classical and recently identified non-classical phosphorylation motifs. IL-ARS also will characterize transgenic Arabidopsis plants over-expressing 14-3-3s, wild type and cation-activation mutants, to test several postulates concerning the role of 14-3-3s in regulation of nitrate reductase activity and steady-state protein level. They will continue collaboration with FL-AES to characterize transgenic corn plants expressing phosphorylation site mutants of sucrose synthase. IL-AES will integrate their metabolite profiling findings with mRNA expression profiling and genetic mapping in maize reproductive tissues to discover the metabolic pathways and genes that are associated with N use efficiency. Also, IL-ARS will continue (in collaboration with NE-AES) studies of the interaction of activase with Rubisco by analysis of Chlamydomonas site-directed large subunit mutants and site-directed mutants of activase proteins. And, IL-ARS will continue collaboration with AZ-ARS to examine the effects of high temperature on inhibitor formation during Rubisco catalysis and the activation of Rubisco by activase.<br /> <br /> KS-AES will collect new genomic and plant physiological data to determine how gene function and physiological response is altered by our rainfall and temperature manipulations. Ongoing studies by KY-AES are aimed at identifying other LSMT substrates and the general mechanism for recognition and methylation of target protein lysyl residues by other protein N-methyltransferases. MI-AES is making a major effort to obtain crystals and three-dimensional structures of the E. coli and potato tuber ADPGlc PPases and of the E. coli glycogen synthase. MO-AES will characterize PDK and E1alpha knockouts under various physiological conditions and stresses, and determine if the different mitochondrial E2 genes code proteins with specific functions for PDC. NE-AES will further characterize PEPC from C. reinhardtii using an RNAi approach, and will examine the role of N959 in the inhibitor binding site. NV-AES will determine if a plasma membrane calcium pump isoform, ACA12, can be used to increase pathogen resistance and will screen mutant plants for stress sensitive phenotypes resulting from gene knockouts in stress-response genes. NV-AES also will continue their functional analysis of CDPKs and closely related protein kinases from Arabidopsis thaliana. Protein-protein interaction studies will be expanded to include both targeted and random yeast two-hybrid screens of other unknown gene products regulated by abiotic stress. SC-AES will examine the link between HXK signaling, the actin cytoskeleton, and mitochondrial function. They also will further examine (in collaboration with IL-ARS) interactions between NO and HXK-dependent signaling processes. WA-AES will repeat field trials this year with transgenic rice, using a much larger scale planting. Plants will be assessed for physiological growth characteristics and leaf starch metabolism. They also will evaluate the potential role of leaf starch serving as a transient sink to alleviate photosynthesis feedback.<br />

Publications

Akhani, H, J Barroca, N Koteyeva, E Voznesenskaya, V Franceschi, G Edwards, SM Ghaffari, W Stichler, H Ziegler 200X) Bienertia sinuspersici (Chenopodiaceae): a new species from SW Asia and discovery of a third terrestrial C4 plant without Kranz anatomy. Systematic Botany, submitted. <br /> <br /> Aluru, M., S.R. Rodermel (2003) Identification of IMMUTANS as a plastid terminal oxidase: its role in differentiation, carotenoid biosynthesis and chlororespiration. Recent Res. Devel. Plant Mol. Biol. 1: 39-55.<br /> <br /> Aluru, M.R, S.R. Rodermel (2004) Control of chloroplast redox by the IMMUTANS terminal oxidase. (Refereed review). Physiologia Plantarum 120: 4-11 (Cover Article).<br /> <br /> AINSWORTH EA, DAVEY PA, HYMUS GJ, OSBORNE CE, ROGERS A, BLUM H, NOSBERGER J, LONG SP (2003) Is stimulation of leaf photosynthesis by elevated carbon dioxide concentration maintained in the long term? A test with Lolium perenne grown for 10 years at two nitrogen fertilization levels under Free Air CO2 Enrichment (FACE). Plant, Cell Environment 26: 705-714.<br /> <br /> AINSWORTH E.A., ROGERS A., BLUM H., NOSBERGER J., LONG S.P. (2003) Variation in acclimation of photosynthesis in Trifolium repens after eight years of exposure to Free Air CO2 Enrichment (FACE). J Exp Botany 54: 2769-2774.<br /> <br /> AINSWORTH E.A., ROGERS A., NELSON R. & LONG S.P. (2004) Testing the "source-sink" hypothesis of down-regulation of photosynthesis in elevated CO2 in the field with single gene substitutions in Glycine max. Agricultural and Forest Meteorology 122: 85-94.<br /> <br /> AINSWORTH EA, TRANEL PJ, DRAKE BG, LONG SP (2003) The clonal structure of Quercus geminata revealed by conserved microsatellite loci. Molecular Ecology 12: 527-532.<br /> <br /> Ballicora, M.A., A.A. Iglesias, J. Preiss (2004) ADP-glucose Pyrophosphorylase; a Regulatory enzyme for Plant Starch Synthesis. Photosynthesis Research, 79: 1-24.<br /> <br /> Barr, J., W.S. White, L. Chen, H. Bae, S. Rodermel (2004) The GHOST terminal oxidase regulates developmental programming in tomato fruit. Plant, Cell Environment 27: 840-852. (Cover article)<br /> <br /> Barroca, J, LR Murphy, VR Franceschi, R Lee, E Roalson, GE Edwards, MS Ku. (200X) Diversification and plasticity of C4 photosynthetic pathway in Eleocharis (Cyperaceae). In: Proceedings of the 13th International Photosynthesis Congress. Springer. In press.<br /> <br /> Baxter I, et al., J. Young, J.F. Harper (2004) Evidence for an endomembrane function of a plasma membrane proton pump. PNAS (in revision).<br /> <br /> Bejar, C.M., M.A. Ballicora, D.F. Gomez-Casati, A.A. Iglesias, J. Preiss (2004) The ADP-glucose pyrophosphorylase from Escherichia coli comprises two tightly bound distinct domains. FEBS Letters, 573: 99-104.<br /> <br /> Below FE, JR Seebauer, M Uribelarrea, MC Schneerman, SP Moose (2004) Physiological changes accompanying long term selection for grain protein in maize. Plant Breed. Rev. 24(1):133-151. <br /> <br /> Bergerou JA, LE Gentry, MB David, FE Below (2004) Role of N2 fixation in the soybean N credit in maize production. Plant and Soil 262:383-394.<br /> <br /> BERNACCHI C.J., CALFAPIETRA C., DAVEY P.A., WITTIG V.E., SCARASCIA-MUGNOZZA G.E., RAINES C.A., LONG S.P. (2003) Photosynthesis and stomatal conductance responses of poplars to free-air CO2 enrichment (PopFACE) during the first growth cycle and immediately following coppice. New Phytologist 159: 609-621.<br /> <br /> BERNACCHI C.J., MORGAN P.B., ORT D.R., LONG S.P. (2004) The growth of soybean under free air [CO2] enrichment (FACE) stimulates photosynthesis while decreasing in vivo Rubisco capacity. Planta 219 (in press).<br /> <br /> BERNACCHI CJ, PIMENTEL C, LONG SP (2003) In vivo temperature response functions of parameters required to model RuBP-limited photosynthesis. Plant, Cell Environment 26: 1419-1430.<br /> <br /> Boxall SF, Foster JM, Bohnert HJ, Cushman JC, Nimmo HG, Hartwell J. (2005) Conservation and divergence of the central circadian clock in the stress-inducible CAM plant Mesembryanthemum crystallinum: clock operation in a CAM halophyte reveals clock compensation against abiotic stress. Plant Physiol. In press.<br /> <br /> Chehab EW, Patharkar OR, Hegeman AD, Taybi T, Cushman JC. (2004) Autophosphorylation and subcellular dynamics of a salt- and water deficit stress-induced calcium-dependent protein kinase from Mesembryanthemum crystallinum. Plant Physiol. 135: 1430-1446.<br /> <br /> Christodoulou, J., A. Malmendal, J.F. Harper, W.J. Chazin (2004) The N-terminal lobe of the CaM-like domain functions as the Ca2+ Sensor for the activation of a calcium-dependent protein kinase (CDPK) from Arabidopsis J. Biol Chem 279:29092-100.<br /> <br /> Cross, J.M., M. Clancy, J.R. Shaw, S. Boehlein, T.W. Greene, R.R. Schmidt, T.W. Okita and L.C. Hannah (2004) A polymorphic motif in the small subunit of ADP-glucose pyrophosphorylase modulates interactions between the small and large subunits. Plant J. In Press.<br /> <br /> Cross, JM, M. Clancy, J.R. Shaw, T.W. Greene, R.R. Schmidt, T.W. Okita, L.C. Hannah (2004) Both subunits of ADP-glucose pyrophosphorylase are regulatory. Plant Physiol. 135:137-144.<br /> <br /> Cruz JA, TJ Avenson, A Kanazawa, K Takizawa, GE Edwards, DM Kramer (200X) Plasticity in light reactions of photosynthesis from energy production and photoprotection. J Exp Bot., In Press.<br /> <br /> DAVEY P, HUNT S, HYMUS G, DRAKE B, DELUCIA E, KARNOSKY, D, LONG, SP (2004) Respiratory oxygen uptake is not decreased by an instantaneous elevation of [CO2], but is increased by long-term growth in the field at elevated [CO2]. Plant Physiology 134: 520-527.<br /> <br /> Davletova, S., L. Rizhsky, H. Liang, Z. Shengqiang, D.J. Oliver, J. Coutu, V. Shulaev, K. Schlauch, R. Mittler (2004) Cytosolic ascorbate peroxidase 1 is a central component of the reactive oxygen gene network of Arabidopsis. Plant Cell, in press.<br /> <br /> Dhingra, A., Portis A.R. Jr, Daniell H. (2004) Enhanced translation of a chloroplast-expressed RbcS gene restores small subunit levels and photosynthesis in nuclear RbcS antisense plants. Proc. Natl. Acad. Sci. USA 101:6315-6320. <br /> <br /> Dinkins, R.D., H.M. Conn, L.M.A. Dirk, M.A. Williams, R.L. Houtz (2003) The Arabidopsis thaliana peptide deformylase 1 protein is localized to both mitochondria and chloroplasts. Plant Sci 165: 751-758.<br /> <br /> Du, Y.C., Peddi S.R., Spreitzer R.J. (2003) Assessment of structural and functional divergence far from the large subunit active site of ribulose-1,5-bisphosphate carboxylase/ oxygenase. J. Biol. Chem. 278: 49401-49405.<br /> <br /> Edwards GE, VR Franceschi, EV Voznesenskaya (2004) Single-cell C4 photosynthesis versus the dual-cell (Kranz) paradigm. Annual Review of Plant Biology 55: 173-196.<br /> <br /> Fay, P.A., A.K. Knapp, J.M. Blair, J.D. Carlisle, J.K. McCarron, B.T. Danner (2003) Rainfall timing, soil moisture dynamics, and plant responses in a mesic tallgrass prairie ecosystem. Pages 147-163 In Changing Precipitation Regimes and Terrestrial Ecosystems. A North American Perspective. (J.F. Weltzin and G.R. McPherson, eds.) University of Arizona Press.<br /> Hardin, S.C., S.C. Huber (2004) Proteasome activity and the post-translational control of sucrose synthase stability in maize leaves. Plant Physiol. Biochem. 42: 197-208.<br /> <br /> Hardin, S.C., H. Winter, S.C. Huber (2004) Phosphorylation of the amino-terminus of maize sucrose synthase in relation to membrane association and enzyme activity. Plant Physiol. 134: 1427-1438.<br /> <br /> Harper, C.W., J.M. Blair, P.A. Fay, A.K. Knapp, J.D. Carlisle (200X) Increased rainfall variability and reduced rainfall amount decreases soil CO2 flux in a grassland ecosystem. Global Change Biology, In press. <br /> <br /> Harper J, G Breton, A Harmon (2004) Decoding CA signals through plant protein kinases Annual Reviews of Plant Biology. 55: 263-88.<br /> <br /> Hegeman A.D., A.C. Harms, M.R. Sussman, A.E. Bunner, J.F.Harper (2004) An isotope labeling strategy for quantifying the degree of phosphorylation at multiple sites in proteins. J Am Soc Mass Spectrom 15: 647-53.<br /> <br /> Hirani, T.A., Tovar-Mendez A., Miernyk J.A., Randall D.D. (2004). Asp-295 is important for phosphorylation of the pyruvate dehydrogenase E1-alpha active-site loop by pyruvate dehydrogenase kinase. Submitted-in revision.<br /> <br /> Houtz, R.L., A.R. Portis Jr. (2003) The life of ribulose-1,5-bisphosphate carboxylase/oxygenase  post-tranlational facts and mysteries. Minireview. Arch Biochem Biophys 414: 150-158 (special issue on C-fixing enzymes).<br /> <br /> Huber, S.C. S.C. Hardin (2004) Numerous post-translational modifications provide opportunities for the intricate regulation of metabolic enzymes at multiple levels. Current Opinion Plant Biology 7: 318-322.<br /> <br /> Hussain,D., M.J. Haydon, Y. Wang, E. Wong, S.M. Sherson, J. Young, J. Camakaris, J.F. Harper, C.S. Cobbett (2004) P-type ATPase heavy metal transporters with roles in essential zinc metabolism in Arabidopsis. Plant Cell 16: 1327-1339.<br /> <br /> Hwang, S.-K., P.R. Salamone, H.Kavakli, C.J. Slattery, T.W. Okita (2004) Rapid purification of the potato ADP-glucose pyrophosphorylase by poly-histidine mediated chromatography. Protein Purif. Express. 38: 99-107.<br /> <br /> Ivanov B, K Asada, D Kramer, GE Edwards (200X) The properties of photosynthetic electron transport in bundle sheath cells of maize. Ascorbate can effectively charge cyclic electron flow. Planta, In Press.<br /> <br /> Karkehabadi, S., Taylor, T.C., Spreitzer, R.J., Andersson, I. (2004) Altered intersubunit interactions in crystal structures of catalytically-compromised ribulosebisphosphate carboxylase/oxygenase. Biochemistry (in press).<br /> <br /> Kim, K., Portis, A.R. Jr. (2004) Oxygen-dependent H2O2 production by Rubisco. FEBS Letters 571: 124-128.<br /> <br /> Koch, K.E. (2004) Sucrose metabolism: Regulatory mechanisms and pivotal roles in sugar sensing and plant development. Current Opin Plant Biol 7: 235-246.<br /> <br /> Kore-eda S, Cushman MA, Akselrod I, Bufford D, Fredrickson M, Clark E, Cushman JC (2004) Transcript Profiling of Salinity Stress Responses by Large-Scale Expressed Sequence Tag Analysis in Mesembryanthemum crystallinum. Gene 341:83-92.<br /> <br /> Kore-eda S, Noake C, Ohishi M, Ohnishi J, Cushman JC (2005) Transcriptional regulation of organellar metabolite transporters during induction of crassulacean acid metabolism in Mesembryanthemum crystallinum. Functional Plant Biology. Submitted.<br /> Kramer DM, TJ Avenson, GE Edwards (2004) Dynamic flexibility in the light reactions of photosynthesis governed by both electron and proton transfer reactions. Trends Plant Science 9: 339-348.<br /> <br /> Kramer DM, TJ Avenson, GE Edwards (2004) Response to Johnson: Controversy remains: regulation of pH gradient across the thylakoid membrane. Trends Plant Science 9 571-572.<br /> <br /> Kramer DM, G Johnson, O Kiirats, GE Edwards (2004) New fluorescence parameters for the determination of QA redox status and excitation energy fluxes. Photosynthesis Res 79:209-218. <br /> <br /> Kramer DM, A Kanazawa, JA Cruz, B Ivanov, GE Edwards (200X) The relationship between photosynthetic electron transfer and its regulation. In: Govindjee, GC Papageorgiou, eds, Chlorophyll Fluorescence: The Signature of Green Plant Photosynthesis. The Netherlands: Kluwer Academic Publishers. In Press.<br /> <br /> LEAKEY A.D.B., BERNACCHI C.J., DOHLEMAN F.G., ORT D.R. & LONG S.P. (2004) Will photosynthesis of maize (Zea mays) in the US Corn Belt increase in future CO2 rich atmospheres? An analysis of diurnal courses of CO2 uptake under free-air concentration enrichment (FACE). Global Change Biology 10: 951-962.<br /> <br /> LONG SP, AINSWORTH EA, ROGERS A, ORT DR (2004) Rising Atmospheric Carbon Dioxide: Plants Face The Future. Annual Reviews of Plant Biology 55: 591-628.<br /> <br /> LONG S.P., BERNACCHI C.J. (2003) Gas exchange measurements, what can they tell us about the underlying limitations to photosynthesis? Procedures and sources of error. J Exp Botany 54: 2393-2401.<br /> <br /> Lonosky, P., X. Zhang, V. Honavar, D. Dobbs, A. Fu, S. Rodermel (2004) A proteomic analysis of maize chloroplast biogenesis. Plant Physiology 134: 560-574.<br /> <br /> Mamedov, T.G., Moellering E.R., Chollet R. (2004) Identification and expression analysis of two genes encoding novel and distinct molecular forms of eukaryotic PEP carboxylase in the green microalga Chlamydomonas reinhardtii. Plant J.. submitted.<br /> <br /> Mazarei, M., K.A. Lennon, D. P. Puthoff, S. R. Rodermel, T. J. Baum (2004) Homologous soybean and Arabidopsis genes share responsiveness to cyst nematode infection. Molecular Plant Pathology 5: 409-423.<br /> <br /> Mazarei, M., K.A. Lennon, D. P. Puthoff, S. R. Rodermel, T. J. Baum (2004) Expression of an Arabidopsis phosphoglycerate mutase homologue is localized to apical meristems, regulated by hormones, and induced by sedentary plant-parasitic nematodes. Plant Mol. Biol. 53: 513-530.<br /> <br /> Mittler, R., S. Vanderauwera, M. Gollery, F. Van Breusegem (2004) The reactive xxygen gene network of plants. Trends Plant Science 9: 490-498.<br /> <br /> MIYAZAKI S, FREDRICKSEN M, HOLLIS KC, POROYKO V, SHEPLEY D, GALBRAITH DW, LONG SP, BOHNERT HJ (2004) Transcript expression profiles of Arabidopsis thaliana grown under controlled conditions and open-air elevated concentrations of CO2 and of O3. Field Crops Research 90: 47-59.<br /> <br /> Moore B.d. (2004) Bifunctional and moonlighting enzymes: lighting the way to regulatory control. Trends Plant Science 9: 221-228. (cover article)<br /> <br /> MORGAN PB, AINSWORTH EA, LONG SP (2003) How does elevated ozone impact soybean? A meta-analysis of photosynthesis, growth and yield. Plant, Cell Environment 26: 1317-1328.<br /> <br /> MORGAN PB, BERNACCHI CJ, ORT DR, LONG SP (2004) An in vivo analysis of the effect of season-long open-air elevation of ozone to anticipated 2050 levels on photosynthesis in soybean. Plant Physiology 135, 2348-2357.<br /> <br /> MORGAN P.B., BOLLERO G., NELSON R.L., LONG S.P. (2005) Season-long elevation of ozone concentration by 20 % under fully open-air conditions decreases the growth and production of Midwest soybean crops by ca. 20 %. Environmental Pollution (in press).<br /> <br /> MORGAN P.B., BOLLERO G., NELSON R.L., DOHLEMAN F.G., LONG S.P. (2005) Smaller than predicted increase in above-ground net primary production and yield of field-grown soybean was found when [CO2] is elevated in fully open-air. Global Change Biology 11 (in press).<br /> <br /> NAIDU SL, LONG, SP (2004) Potential mechanisms of low-temperature tolerance of C4 photosynthesis in Miscanthus x giganteus: an in vivo analysis. Planta 219 (in press). <br /> <br /> NAIDU SL, MOOSE SP, AL-SHOAIBI AK, RAINES CA, LONG SP (2003) Cold tolerance of C4 photosynthesis in Miscanthus x giganteus: Adaptation in amounts and sequence of C4 photosynthetic enzymes. Plant Physiology 132: 1688-1697. <br /> <br /> Park, S., S. Rodermel (2004) Mutations in ClpC2/Hsp100 suppress the requirement for FtsH in thylakoid membrane biogenesis. Proc. Natl. Acad. Sci. USA 101: 12765-12770.<br /> <br /> Peddi, S.R., Karkehabadi, S., Anwaruzzaman, M., Andersson, I., Spreitzer, R.J. (2004) Evolutionary divergence in the structure of the small-subunit bA-bB loop of ribulose-1,5-bisphosphate carboxylase/oxygenase is not essential for assembly but influences large-subunit catalysis. In Photosynthesis: Fundamental Aspects to Global Perspectives, eds. A. van der Est and D. Bruce. Allen Press, Lawrence, Kansas (in press).<br /> <br /> Portis, A.R. Jr. (2004) Rubisco activase. Encylopedia of Plant and Crop Science, R.M. Goodman ed., Marcel Dekker, Inc, New York, NY, pp. 1117-1119. <br /> <br /> Preiss, J. (2004) The Biochemistry and Molecular Biology of Starch synthesis. IN Starch in Food. Woodhead Publishing Ltd, In Press.<br /> Puthoff, D.P., D. Nettleton, S.R. Rodermel, T.J. Baum (2003) Arabidopsis gene expression changes during cyst nematode parasitism revealed by statistical analyses of microarray expression profiles. Plant Journal 33: 1-11.<br /> <br /> Rodermel, S., S. Park. 2003. Pathways of intracellular communication: tetrapyrroles and plastid-to-nucleus signaling. BioEssays 25: 631-636. <br /> <br /> Rodriguez Milla MA, Uno Y, Townsend J, Maher E, Cushman JC (2005) Identification of potential substrates of AtCPK11, a calcium-dependent protein kinase induced by water-deficit and salt stress in Arabidopsis thaliana. Submitted.<br /> <br /> ROGERS A., ALLEN D.J., DAVEY P.A., MORGAN P.B., AINSWORTH E.A., BERNACCHI C.J., CORNIC G., DERMODY O., DOHLEMAN F.G., HEATON E.A., MAHONEY J., ZHU X.G., DELUCIA E.H., ORT D.R., LONG S.P. (2004) Leaf photosynthesis and carbohydrate dynamics of soybeans grown throughout their life-cycle under Free-Air Carbon dioxide Enrichment. Plant Cell Environment 27: 449-458.<br /> <br /> Roychaudhuri, R., Sarath G., Zeece M., Markwell, J. (2004) Stability of the allergenic soybean Kunitz trypsin inhibitor. Biochim. Biophys. Acta 1699: 207-212.<br /> <br /> Sakulsinghharoj, C., S.-B. Choi, S.-K. Hwang, G.E. Edwards, J. Bork, C.R. Meyer, J. Preiss, T.W. Okita (2004) Engineering starch biosynthesis for increasing rice seed weight: the role of the cytoplasmic ADP-glucose pyrophosphorylase. Plant Science 167: 1323-1333<br /> <br /> Satagopan, S., Spreitzer R.J. (2004) Substitutions at the Asp-473 latch residue of Chlamydomonas ribulosebisphosphate carboxylase/oxygenase cause decreases in carboxylation efficiency and CO2/O2 specificity. J. Biol. Chem. 279: 14240-14244.<br /> <br /> Schiøtt, M., S. Romanowsky, M.K. Jakobsen, L. Bækgaard, M.G. Palmgren, J.F. Harper (2004) A plant plasma membrane Ca2+ pump is required for normal pollen tube growth and fertilization. PNAS 101: 9502-9507.<br /> <br /> Sebastia, C.H., S.C Hardin, S.D.Clouse, J.J. Kieber, S.C. Huber (2004) Identification of a new motif for CDPK phosphorylation in vitro that suggests ACC synthase may be a CDPK substrate. Arch. Biochem. Biophys. 428: 81-91.<br /> <br /> Sebastia, C.H., F. Marsolais, C. Saravitz, D.W. Israel, R. Dewey, S.C. Huber (200X) Possible role of amino acids in the control of storage product accumulation in developing soybean seeds. J. Exp. Botany, submitted.<br /> <br /> Seebauer JR, SP Moose, BJ Fabbri, LD Crossland, FE Below (2004) Amino acid metabolism in maize earshoots: Implications for assimilate preconditioning and nitrogen signaling. Plant Physiol. (in press).<br /> <br /> Stessman, D., M. Spalding, S. Rodermel (2004) Short and long term regulation of photosynthesis during leaf development. In Handbook of Photosynthesis. M. Pessarakli, ed. (Marcel Dekker, Inc., New York) (in press). <br /> Tovar-Mendez, A., Hirani T.A., Miernyk J.A., Randall D.D. (2004). Analysis of the catalytic mechanism of pyruvate dehydrogenase kinase. Arch. Biochem. Biophys. In press.<br /> <br /> Trievel, R.C., E.M. Flynn, R.L. Houtz, J.H. Hurley (2003) Mechanism of multiple lysine methylation by the SET domain enzyme Rubisco LSMT. Nature Structural Biology 10: 545-552.<br /> <br /> Uribelarrea, M, FE Below, SP Moose (2004) Grain composition and productivity of maize hybrids derived from the Illinois protein strains in response to variable nitrogen supply. Crop Sci. 44:1593-1600.<br /> <br /> Voznesenskaya, EV, S Choung, GE Edwards, VR Franceschi (200X) Distribution of components of C4 photosynthesis in the triple layered chlorenchyma of Aristida (Poaceae). Functional Plant Biology, In press. <br /> <br /> Voznesenskaya EV, S Chuong, O Kiirats, VR Franceschi, GE Edwards (200X) Evidence that C4 species in genus Stipagrostis, family Poaceae, is NADP-malic enzyme subtype with nonclassical type of Kranz anatomy (Stipagrostoid). Plant Science. In press.<br /> <br /> Voznesenskaya EV, VR Francheschi, GE Edwards (2004) Light dependent development of single cell C4 photosynthesis in cotyledons of Borszczowia aralocaspica (Chenopodiaceae) during transformation from a storage to a photosynthetic organ. Annals of Botany 93: 1-11.<br /> <br /> Wachter, R., M. Langhans, R. Aloni, S. Gotz, A. Weilmunster, A. Koops, L. Temguia, I. Mistrik, J. Pavlovkin, U. Rascher, K. Schwalm, K. E. Koch, C. I. Ulrich (2003) Vascularization, high-volume solution flow, and localized roles for enzymes of sucrose metabolism during tumorigenesis by Agrobacterium tumefaciens. Plant Physiology. 133:1024-1037.<br /> <br /> Walker D, G Edwards (2004) Photosynthetic Carbon Assimilation. In: Molecular to Global Photosynthesis. Series on Photoconversion of Solar Energy, v. 2. Eds. MD Archer and J Barber. pp. 189-220. Invited chapter. Singapore: World Scientific Pres.<br /> <br /> Weltzin, J.F. M.E. Loik, S. Schwinning, D.G. Williams, P. Fay, B. Haddad, J. Harte, T.E. Huxman, A.K. Knapp, G. Lin, W.T. Pockman, M.R. Shaw, E. Small, M.D. Smith, D.T. Tissue, J.C. Zak (2003) Assessing the response of terrestrial ecosystems to potential changes in precipitation. BioScience 53: 941-952.<br /> <br /> Wubben, M.J.E., S.R. Rodermel, T.J. Baum (2004) Mutation of a UDP-glucose-4-epimerase alters root ethylene responses and nematode susceptibility in Arabidopsis thaliana. Plant Journal (in press). <br /> <br /> Yep, A., M. A. Ballicora, M. N. Sivak, J. Preiss (2004) Identification and characterization of a critical region in the glycogen synthase from Escherichia coli. J. Biol. Chem. 279: 8359-8367.<br /> <br /> Yep, A., M. A. Ballicora, M. N. Sivak, J. Preiss (2004) The active site of the Escherichia coli glycogen synthase is similar to the active site of retaining GT-B glycosyltransferases. (2004) Biochem. Biophys. Res. Commun. 316: 960-966.<br /> Yep, A., C.M. Bejar, M.A. Ballicora, J.Dubay, A.A. Iglesias, J. Preiss, (2004) An assay for the ADP-glucose pyrophosphorylase that measures the synthesis of radioactive ADP-glucose with glycogen synthase. Analytical Biochemistry. 324: 52-59.<br /> <br /> Yu, F., S. Park, S.R. Rodermel (2004) The Arabidopsis FtsH metalloprotease gene family: interchangeability of subunits in chloroplast oligomeric complexes. Plant Journal 37: 864-876.<br /> <br /> Zheng, P., K. Ammar, A.-M. Girard, S. Rodermel, D.R. Thomas, L. Ning, J.B. Callis, G.E. Edwards, L. Daley (2003) Test of an in vivo method to detect chloroplast division in crop plants. Part III: Statistical proofs of observation and general utility of the method. Spectroscopy 18: 102-105.<br /> <br /> ZHU X, PORTIS AR, LONG SP (2004) Would transformation of C3 plants with foreign Rubisco increase productivity? Plant Cell Environment 27: 155-165. <br /> <br /> ZHU X.G., ORT D.R., WHITMARSH J., LONG S.P. (2004) The slow reversibility of photosystem II thermal energy dissipation on transfer from high to low light may cause large losses in carbon gain by crop canopies: a theoretical analysis. J Exp Botany 55: 1167-1175.<br /> <br /> <br /> <br /> NC-1-142 PATENT APPLICATION: <br /> <br /> H. Winter, S.C. Huber, C. Larabell (Filed Oct 17, 2004) (LBNL Docket No. JIB-1571) Synthetic peptides that cause F-actin bundling and block actin depolymerization. <br /> <br /> <br /> NC-1-142 PATENTS AWARDED:<br /> <br /> Randall, D.D., Mooney B.P., Johnston M.L, Luethy M.H., Miernyk J.A. (2004) U.S. Patent No. 6,773,917 entitlted: Use of DNA encoding plastid pyruvate dehydrogenase and branched-chain oxoacid dehydrogenase components to enhance polyhydroxyalkanoate biosynthesis in Plants.<br />

Impact Statements

1. Future increases in productivity, essential to support US agriculture and global demands for food and fiber, will be dependent on fundamentally new approaches to increase the capacity of crop plants to produce the nutrients that support growth of harvested plant parts, such as tubers and seeds. Basic research results reported in this year&lsquo;s project update illustrate these approaches and directly contribute to the required knowledge base to effect these changes.
2. Fundamental studies of the biochemical mechanisms that control critical plant processes will directly contribute to the design of strategies to manipulate the photosynthetic capacity and quality of crop plants. The current report indicates that FtsH metalloproteases, such as VAR2, play an important role early in the process of plastid membrane biogenesis, a likely key component for modulating photosynthetic output.
3. The genetic engineering of Rubisco to increase net photosynthesis is proving to be difficult and various alternative strategies need to be explored. The reported results using chloropolast transformation have opened a new avenue for the evaluation and modification of foreign Rubisco genes in planta.
4. In order to increase crop yield potential and quality, it is essential to have fundamental knowledge of the underlying metabolic components that control assimilate production and utilization, and hence plant growth and development. Evidence that up-regulated forms of AGPase can increase starch biosynthesis in Arabidopsis and rice indicates there is potential to increase the capacity to utilize products of photosynthesis and thus increase plant growth.
5. Projected climate changes represent a significant threat to future crop and range production. Current results from field level manipulation of CO2, ozone, and precipitation will provide a basis for development of better mechanistic models to predict crop responses to global climate change. Ongoing experiments to characterize critical regulatory gene networks that control plant stress responses will provide targets for future genetic engineering.

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Report Information

Participants

FL  AES (K. Koch);
IA  AES (A.D. Knapp, S. Rodermel);
IL  AES/ARS (F. Below, H. Bohnert, S.C. Huber, S. Long, A. Portis);
KS  AES (A.K. Knapp);
KY  AES (R. Houtz);
MI  AES (W. Loescher, J. Preiss);
MN  AES (R. Jones);
MO  AES (D. Randall);
NE  AES (R. Chollet, J. Markwell, R. Spreitzer);
NV  AES (J. Cushman, J. Harper, R. Mittler);
OR  AES (L. Daley);
PA  AES (M. Guiltinan);
SC  AES (B. Moore);
WA  AES (G. Edwards, T. Okita);
WI  AES (S. Duke)

Brief Summary of Minutes

Annual Meeting Date and Location:
November 11-12, 2005
Florida AES host
Reitz Union, University of Florida, Gainesville, FL

Attending Members:
Dr. Robert Aiken Kansas AES
Dr. Fred Below Illinois AES
Dr. Raymond Chollet Nebraska AES
Dr. Larry Daley Oregon AES
Dr. Robert Houtz Kentucky AES
Dr. Steven Huber Illinois USDA/ARS
Dr. Robert Jones Minnesota AES
Dr. Karen Koch Florida AES
Dr. Wayne Loescher Michigan AES
Dr. Gail McLean CSREES Representative
Dr. Ronald Mittler Nevada AES
Dr. Brandon Moore South Carolina AES
Dr. Archie Portis Illinois USDA/ARS
Dr. Jack Preiss Michigan AES
Dr. Michael Salvucci Arizona USDA/ARS
Dr. Robert Spreitzer Nebraska AES

Additional Members Sending Reports:
Dr. Hans Bohnert Illinois AES
Dr. Steve Long Illinois
Dr. Doug Randall Missouri AES
Dr. John Markwell Nebraska AES
Dr. Jeff Harper Nevada AES
Dr. John Cushman Nevada AES
Dr. JC Jang Ohio AES
Dr. Mark Guiltinan Pennsylvania AES
Dr. Glenda Gillaspy Virginia AES
Dr. Gerry Edwards Washington AES (retiring)

Members Not Continuing:
Dr. Thomas Marler Guam AES
Dr. Gretchen Sassenrath-Cole Mississippi AES
Dr. Donald Thompson Pennsylvania AES

Attending Guests:
Dr. Christoff Benning Prospective new member (Michigan AES)
Dr. William Ogren Emeritus member
Dr. George Bowes University of Florida


The annual meeting of NC-1-142 was called to order by Dr. Karen Koch, Chair. Following a welcoming address and review of achievements by Dr. Mark McLellan (Director, Florida AES), each attending member gave a 20 min formal presentation of research progress. Each presentation was followed by a 5 min discussion period. Collaborative planning and discussions also occurred during breaks, breakfast, lunch, and dinner, as well as among early-arriving participants during dinner on the previous evening. Dr. Gail McLean (CSREES Representative) reviewed USDA-NRI funding opportunities and strategic goals. Prior to dinner, an informal mixer provided an opportunity to interact with additional faculty from the University of Florida (Drs. Kevin Folta, Don McCarty, Curtis Hannah, and Alice Harmon).

The business meeting was called to order after the talks and before the evening mixer, and lasted approximately 50 min. Having reviewed Dr. Christoff Benning's research area (via his formal presentation) and curriculum vitae, the attending members voted unanimously to approve his participation as a new member of NC-1-142. A second potential new member (Dr. Lloyd Wilson, Texas AES) was also considered for membership. Following lengthy discussion by participating members and consideration of written comments from members not attending, the majority of members agreed that Dr. Lloyd's research in entomology would not address the objectives of NC-1-142. Discussion then focused on the lack of attendance at the annual meeting by several members. The Chair was charged with contacting those members who have failed to attend or provide annual reports (S. Duke, T. Marler, A. Knapp) to request that they either resign from the project or participate next year. With respect to the format of future meetings, the participating members agreed that (1) the chair will choose the location (university/AES vs. hub city) of the meeting and (2) non-member attendees at the annual meeting will be approved by a vote of the members prior to being invited to attend the meeting. Dr. Michael Salvucci was elected by unanimous vote to chair/host the 2008 annual meeting. It was agreed that the annual meeting will continue to be scheduled for the second weekend before Thanksgiving.

Key discussions at the meeting
Discussions centered on the collaborative research results outlined in the reports from the attending AES/ARS representatives, the evaluation of a visiting candidate for new membership, and the comments by Dr. McLean. The primary issues of the business meeting are enumerated above.

Assigned responsibilities
As decided by NC-1-142 participants, officers for next year will be Dr. Robert Houtz (Chair, Kentucky AES), Dr. Robert Spreitzer (Vice-Chair, Nebraska AES), and Dr. Michael Salvucci (Secretary, Arizona USDA/ARS).

Accomplishments

Photosynthesis is the fundamental process that enables the synthesis of sugars and all other biomolecules required for plant growth. Photosynthesis uniquely integrates light, photochemistry, biochemical fixation of atmospheric carbon dioxide, and the utilization of inorganic nutrients to sustain and direct crop production under a variety of environmental conditions. This regional research project is an integrated cooperative program in which the expertise of AES and ARS investigators is applied to four aspects of the photosynthetic process.<br /> <br /> Objective 1: Photochemistry and the biogenesis of the photosynthetic apparatus.<br /> <br /> Objective 2: Photosynthetic capture and photorespiratory release of CO2.<br /> <br /> Objective 3: Mechanisms regulating photosynthate partitioning.<br /> <br /> Objective 4: Developmental and environmental limitations to photosynthesis.<br /> <br /> <br /> Objective 1: Photochemistry and the biogenesis of the photosynthetic apparatus. Cooperating AES and or ARS-USDA: IA (Rodermel), WA (Edwards, Okita)<br /> <br /> <br /> Analysis of photochemistry by chlorophyll fluorescence, and the function of cyclic electron flow (WA-AES [Edwards, Okita]) indicated that primary photochemical reactions could be enhanced by elevated rates of starch metabolism. The enhanced starch deposition was observed in Arabidopsis plants transformed to overexpress a large subunit of ADPglucose pyrophosphorylase that was less sensitive to inhibition by inorganic phosphate. These plants also showed a 14 to 26% increase in starch turnover. An impact on primary photosynthetic reactions was also evident in almost all instances. Also, the transgenic plants had greater rates of CO2 assimilation, elevated O2 sensitivity, and grew more rapidly. Collectively, data indicated that increased capacity for starch metabolism led to higher photosynthetic capacity and reduced photosynthetic feedback, and this in turn resulted in higher net productivity. Work is in progress to test this relationship in rice as well.<br /> <br /> IA-AES (Rodermel) has been exploiting a number of vareigtaed utants with green-and-white sectored leaves to dissect the molecular and biochemical coordination between nuclear and plastid gene expression. He was on leave at the National Science Foundation in Washington D.C. this year and will be updating progress on this objective next year.<br /> <br /> Objective 2: Photosynthetic capture and respiratory release of CO2. Cooperating AES and.or ARS-USDA: AZ (Salvucci), IL (Portis), KY (Houtz), MO (Randall), NE (Chollet, Spreitzer), NV (Cushman), WA (Edwards, Okita)<br /> <br /> <br /> Together, AZ (Salvucci), IL (Portis), and NE (Spreitzer), have examined structural features mediating interaction between RuBISCO (a primary enzyme of photosynthetic CO2 assimilation) and an enzyme mediating its activation. Mutant forms of the RuBISCO enzyme were generated and examined in Chlamydomonas by Spreitzer (NE). Then, in collaboration with Portis (IL), the mutants were used to further test which sites in the RuBISCO protein were most important for recognition by the activase enzyme. Mutant forms of RuBISCO in tobacco and spinach (Portis, IL) were also examined by Salvucci (AZ) for their specific capacity to interact with the activase. Still further collaborative work between Salvucci (AZ) and Moore (SC) addressed the potential effects of sugar sensing on the activase. The collective importance of this work lies in its potential to increase the activation and thus overall effectiveness of RuBISCO (an otherwise inefficient enzyme in vivo.<br /> <br /> Related work by Houtz (KY) addressed mechanisms of import, assembly, and processing of the RuBISCO enzyme in the chloroplast. His group has been identifying protein specificity determinants for key protein processing enzymes by utilizing alternative protein substrates. Results thus far have suggested that a number of alternative proteins can serve as substrates for the RuBISCO LSMT. Additional efforts by this group have shown that a Chloroplast-localized peptide deformylase (DEF) is essential to processing of numerous chloroplast proteins (such as assembly of PSII polypeptides). Their work has been furthered by newly available crystal structure that points toward a unique binding cleft for this function of the DEF protein.<br /> <br /> Complementary advances in regulation of photosynthetic enzymes have also been achieved by Chollet (NB) focusing on two different points of control. One of these is the PEPc enzyme (primary enzyme of photosynthetic CO2 assimilation for C-4 type plants and for anapleurotic reactions in multiple tissues), and another is a kinase (PpcK) that regulates PEPc enzymes. His group has approached both enzymes with a combined mutagenic and genomic approach. They have been able to define roles of different, closely related members of gene families, and for several of these proteins, they have also identified structural features critical to their function.<br /> <br /> Cushman (NV) is studying collective regulation of the enzymes above by focusing on an unusual type of photosynthesis that occurs only in succulent plants (CAM, or Crassulacean Acid Metabolism). His group has used Mesembryanthemum (the ice plant), in conjunction with a molecular-genetic approach, to identify genes that control collective regulation of photosynthetic enzymes. These regulatory mechanisms can control a switch from one mode of photosynthesis to another, so may offer novel approaches to biochemical modulation of photosynthesis.<br /> <br /> Finally, CO2 losses from plants can reduce their ultimate productivity, and a central point of regulation in this process has been studied by Randall (MO). His group has found that the pivotally-positioned, mitochondrial pyruvate dehydrogenase complex (mtPDC) can be regulated in a number of ways, and at least one of these is unique to plants. The plant mtPDC can be controlled by both kinase and phosphatase enzyme systems, but unlike mammalian PDC, appears to be regulated by a single phosphorylation site. Function of the relevant plant kinases and phosphatases has been initially dissected by Randall (MO) using a combination of mutational analyses and studies of expression patterns. <br /> <br /> <br /> Objective 3: Mechanisms regulating photosynthate partitioning. Cooperating AES and or ARS-USDA: FL (Koch), IA (Knapp, Rodermel), IL (Bohnert, Huber), MI (Preiss, Loescher), NE (Chollet), NV (Harper), PA (Guiltinan), SC (Moore), WA (Edwards, Okita), WI (Duke)<br /> <br /> Koch (FL) and Huber (IL) have collaboratively determined that the fate of photosynthate can be altered by subtle changes in key enzymes of sucrose metabolism, especially in grains (sucrose is the long-distance transport form for photosynthates in the majority of vascular plants). Sucrose synthase (a reversible enzyme that cleaves sucrose) can be up-regulated by alterations in its capacity to be phosphorylated at different sites on the protein, and data from transgenic plants expressing the different forms indicate altered extents of grain-fill and cell wall biosynthesis.<br /> <br /> Huber (IL) has further examined post-translational regulatory mechanisms for these sucrose synthases, and also for other enzymes central to partitioning of photosynthetic resources. In particular, the Huber (IL) and Moore (SC) groups have defined control mechanisms that involve protein longevity and influence of sugar sensing. They have focused much of this work on HXK (hexokinase) enzymes due to the central importance of these enzymes in sensing sugar availability, and in the sensitivity of both HXK and sugar sensing to NO.<br /> <br /> <br /> Regulation of sugar metabolism and sugar sensing has also been the central focus of the Jang (OH) and Moore (SC) programs. Using a combination of Arabidopsis mutants and microarray analyses, Jang (OH) has determined that bZIP genes may have central roles in sugar sensing. Sugar responsiveness was identified for up-stream elements and trans-acting factors. Moore (SC) has found that actin may be involved in linking mitochondrial sugar-sensing signals to nuclear responses.<br /> <br /> <br /> Photosynthate partitioning to starch has been the focal point of work by both the Guiltinen (PA) and Preiss (MI) labs. The Preiss group (MI) has examined phylogenetic relationships between genes encoding subunits of the ADPG pyrophosphorylase enzyme (catalyzing a rate-limiting step in starch biosynthesis) and suggests that the two subunits evolved from a common catalytic ancestor. The Guiltinan (PA) group has developed and studied maize lines carrying specific mutations of-, and a gene-dosage series for- SBE (starch branching enzyme). Differences in the quality and quantity of starch were evident, and are being further explored. <br /> <br /> <br /> Okita (WA), Edwards (WA), and Loescher (MI) have examined photosynthate partitioning to sugar-alcohols, not only because these are primary transport sugars in many species, but also because they can function as antioxidants. Loescher (MI) has found that genes for sorbitol production in apples are expressed most strongly during periods of rapid fruit growth in apples. They have also found that biosynthesis of the sugar alcohols is most extensive under stress conditions and imply potential for enhancing salt and drought tolerance. In collaborative efforts (WA + MI) greater photosynthetic tolerance to salt stress was observed in transgenic Arabidopsis plants engineered to produce manitol.<br /> <br /> <br /> Related sugar-alcohol work by Gilaspy (VA) focused on inositol (myo-inositol) and its conversion to pectic compounds, other sugar alcohols (ononitol, pinitol), and signal molecules (phosphatidylinositol phosphatases). Synthesis and catabolism of the inositol is regulated by three families of enzymes (MIPS, IMPs, and MIOXs) and the Gilaspy (VA) lab is beginning to dissect regulatory roles for each of them.<br /> <br /> <br /> Objective 4: Developmental and environmental limitations to photosynthesis. Cooperating AES and or ARS-USDA: AZ (Salvucci), IL (Below, Bohnert, Long), KS (Knapp), MI (Loescher), MN (Jones), NE (Markwell), NV (Cushman, Harper, Mittler), OR (Daley), WA (Edwards, Okita)<br /> <br /> <br /> Four NC-1-142 groups are addressing potential for enhanced stress tolerance of photosynthesis by examining phosphorylation-based regulatory signals (Harper [NV], Huber [IL], Cushman (NV), and Gilaspy [VA]). The Harper (NV) and Huber (IL) labs (individually and collaboratively) examined CDPKs (kinases that activate and inactivate other proteins) involved in responses to biotic and abiotic stresses. Data indicated involvement of calcium signals, so further dissection of the CDPK roles is planned. Cushman (NV) studied protein-protein interactions to identify substrates of CDPKs that might mediate their influence on stress tolerance. They also identified cellular and sub-cellular sites where such interactions would occur. Gilaspy (VA) investigated the substrate preferences for a group of At5PTases (myo-inositol polyphosphate 5-phosphatases) that could potentially be altered to enhance stress tolerance. <br /> <br /> <br /> Work by Salvucci (AZ) addressed a potential means of enhancing heat tolerance of the photosynthetic process. His group identified a chloroplast protein that binds to RuBISCO (a primary enzyme of photosynthetic CO2 assimilation in most plants), and has homology to heat shock proteins. This is consistent with a possible protective role for this protein that might aid stability of RuBISCO under heat stress.<br /> <br /> <br /> Thermotolerance was examined from a different direction by the Aiken (KS) group, who focused, instead, on cold stress. They have selected sorghum lines with elevated cold tolerance that could improve ultimate photosynthetic potential by allowing earlier planting. They have also found lines with altered leakage of CO2 from bundle-sheaths.<br /> <br /> <br /> The Below (IL) group worked on responses of different maize lines to low-nitrogen conditions. Data were consistent with the suggestion that asparagine levels could serve as an indicator of source-N status. Studies were geared toward ultimately enhancing conversion of photosynthetic products to harvestable yield under low-N conditions.<br /> <br /> <br /> Diverse stresses can result in metabolic alterations that include oxidative stress studied by Mittler (NV), or NADPH/NADP imbalance examined by Markwell (NE). Mittler (NE) has developed a transgenic Arabidopsis system that will produce excess oxidants when exposed to moderate levels of light. He will use these materials to further test means of protecting against this internal manifestation of stress. Markwell (NE) has found that leaves can utilize formate, possibly advantageous in adjusting NADPH/NADP ratios as well as providing a second source of CO2.<br /> <br /> <br /> Finally, the Bohnert (IL) and Long (IL) groups have pursued both drought and atmospheric stresses at levels from transgenic Arabidopsis to field-site alterations in CO2 and ozone levels. Bohnert (IL) has found that water transport by aquaporin proteins is also related to roles of aquaporins in vesicle movement within cells under stress. They have also identified a number of stress-responsive genes in Arabidopsis. In collaboration with the Long (IL) group, they have also profiled metabolite changes in field-grown plants exposed to different atmospheric stresses. Long (IL) and coworkers found that long-term elevation of CO2 significantly altered bacterial species in the soil, and did not increase ultimate crop yields as much as expected. They suggest that nitrogen limitations are likely to restrict yields and hotosynthetic rates as global CO2 levels rise. Ozone exposure had severe effects on photosynthesis and reduced yield by about 20%.<br /> <br /> <br /> Project Participant Plans for 2005-2006:<br /> <br /> <br /> Collaborations prominent in plans for the coming year include the following: Salvucci (AZ) and Portis (IL) will attempt to crystallize the enzyme that activates RuBISCO (the primary enzyme for photosynthetic CO2 assimilation in most plants). Spreitzer (NB) and Salvucci (AZ) will further examine interactions between this activase enzyme and RuBISCO using directed mutants of spinach and Chlamydomonas enzymes. Both Cushman (NV) and Randall (MO) will also use their newly-generated mutants for more in-depth analyses of enzyme regulation. Collaborative plans by Koch (FL) and Huber (IL) will target phenotypic and biochemical consequences of transgenic maize plants altered in their regulation of a key enzyme for sucrose metabolism (the reversible sucrose synthase). Huber (IL) and Moore (SC) have obtained transgenic Arabidopsis plants that will also further their investigations into the significance of NO to plant hexokinase regulation (and possibly sugar-sensing). Researchers studying phosphorylation-based regulation of stress responses (Harper [NV], Huber [IL], Cushman [NV], and Gilaspy [VA]) will coordinate investigations into transgenic Arabidopsis with altered stress responses.<br /> <br /> <br /> Related studies by individual AES are as follows: Salvucci (AZ) will examine effects of altered activase enzymes on tolerance of RuBISCO enzymes to both high- and low- temperatures, the former involving interactions with putative protective proteins. Portis (IL) will continue exploration of chloroplast transformation as a means of introducing specific alterations to the photosynthetic machinery. Jang (OH) will use chip-on-chip analyses to further elucidate roles of bZIP genes in sugar-sensing by plants. The Below (IL) group will integrate their metabolic profiling efforts with those of expression profiling and gene mapping to define metabolic pathways and genes that respond to low-N stress. The Bohnert (IL) and Long (IL) groups will continue their collaboration on the molecular and field responses to drought and atmospheric stresses (high CO2 and ozone).<br />

Publications

2005 NC-1-142 Refereed Publications<br /> <br /> Ainsworth EA, Long SP (2005) What have we learned from 15 years of free-air CO2 enrichment (FACE)? A meta-analytic review of the responses of photosynthesis, canopy. New Phytol165: 351-371<br /> <br /> Ainsworth EA, Rogers A, Nelson R, Long SP (2004) Testing the "source-sink" hypothesis of down-regulation of photosynthesis in elevated CO2 in the field with single gene substitutions in Glycine max. Agricul Forest Meteorology 122: 85-94<br /> <br /> Akhani H, Barroca J, Koteyeva N, Voznesenskaya E, Franceschi V, Edwards G, Ghaffari SM, Stichler W, Ziegler H (2005) Bienertia sinuspersici (Chenopodiaceae): a new species from SW Asia and discovery of a third terrestrial C4 plant without Kranz anatomy. Systematic Bot 30: 290-301<br /> <br /> Amtmann A, Bohnert HJ, Bressan RA (2005) Abiotic stress and plant genome evolution: the search for new models. Plant Physiol 138: 127-130 <br /> <br /> Ballicora MA, Dubay JR, Devillers CH, Preiss J (2005) Resurrecting the ancestral enzymatic role of a modulatory subunit. J Biol Chem 280: 10189-10195 [Cited by J.B.C. as paper of the week (March 18, 2005 issue)]<br /> <br /> Barroca J, Murphy LR, Franceschi VR, Lee R, Roalson E, Edwards GE, Ku MS (2005) Diversification and plasticity of C4 photosynthetic pathway in Eleocharis (Cyperaceae). In van der Est A, Bruce D, eds, Photosynthesis: Fundamental Aspects to Global Perspectives. Springer, pp 646-648<br /> <br /> Baxter I, Young JC, Armstrong G, Foster N, Bogenschutz N, Cordova T, Peer WA, Hazen SP, Murphy AS, Harper JF (2005) A plasma membrane H+-ATPase is required for the formation of proanthocyanidins in the seed coat endothelium of Arabidopsis thaliana. Proc Natl Acad Sci USA 102: 2649-2654<br /> <br /> Bernacchi CJ, Morgan PB, Ort DR, Long SP (2005) The growth of soybean under free air CO2 enrichment (FACE) stimulates photosynthesis while decreasing in vivo Rubisco capacity. Planta 220: 434-446<br /> <br /> Bohnert HJ (2004) Functional genomics of plant salinity tolerance. In Leister D, ed, Functional Plant Genomics. Haworth Press, New York, pp 451-484<br /> <br /> Bohnert HJ, Bressan RA, Hasegawa PM (2005) Ion homeostasis and water deficit. In Ribaut JM, ed, Drought Tolerance in Cereals. Haworth Press, New York, In press<br /> <br /> Boxall SF, Bohnert HJ, Cushman JC, Nimmo HG, Hartwell J (2005) Circadian clock-associated genes CCA1/LHY, TOC1, ELF4, ZTL, FKF1, GI and ELF3 in the stress-inducible CAM plant M. crystallinum. Plant Physiol 137: 969-982<br /> <br /> Boxall SF, Foster JM, Bohnert HJ, Cushman JC, Nimmo HG, Hartwell J (2005) Conservation and divergence of the central circadian clock in the stress-inducible CAM plant Mesembryanthemum crystallinum: clock operation in a CAM halophyte reveals clock compensation against abiotic stress. Plant Physiol 137: 969-982<br /> <br /> Bressan RA, Bohnert HJ, Hasegawa PM (2005) Bioengineering for plant abiotic stress tolerance. In Nguyen H, Bohnert HJ, eds, Engineering of Plant Metabolic Pathways. Elsevier, Netherlands, In press <br /> <br /> Chiang YJ, Stushnoff C, McSay AE, Jones, ML, Bohnert HJ (2005) Overexpression of mannitol-1-phosphate dehydrogenase increases mannitol production and enhances chilling tolerance in Petunia. J Amer Soc Hort Sci 130: 605-610 <br /> <br /> Crafts-Brandner SJ, Salvucci ME (2004) Analyzing the impact of high temperature and CO2 on net photosynthesis: biochemical mechanisms, models and genomics. Field Crops Res 90: 75-85<br /> <br /> Cruz JA, Avenson TJ, Kanazawa A, Takizawa K, Edwards GE, Kramer DM (2005) Plasticity in light reactions of photosynthesis for energy production and photoprotection. J Exp Bot. 56: 395-406<br /> <br /> Cushman JC (2005) Crassulacean acid metabolism: recent advances and future opportunities. Functional Plant Biol 32: 375-380<br /> <br /> Davey PA, Hunt S, Hymus GJ, DeLucia EH, Drake BG, Karnosky DF, Long SP (2004) Respiratory oxygen uptake is not decreased by an instantaneous elevation of CO2 , but is increased with long-term growth in the field at elevated CO2. Plant Physiol 134: 520-527<br /> <br /> Davletova S, Rizhsky L, Liang H, Shengqiang Z, Oliver DJ, Coutu J, Shulaev V, Schlauch K, Mittler R (2005) Cytosolic ascorbate peroxidase 1 is a central component of the reactive oxygen gene network of Arabidopsis. Plant Cell 17: 268-281<br /> <br /> Davletova S, Schlauch K, Coutu J, Mittler R (2005) The zinc-finger protein Zat12 plays a central role in reactive oxygen and abiotic stress signaling in Arabidopsis. Plant Physiol 139: 847-856<br /> <br /> Ehsan H, Ray WK, Phinney B, Wang X, Hube, SC, Clouse SD (2005) Interaction of Arabidopsis BRASSINOSTEROID-INSENSITIVE 1 receptor kinase with a homolog of mammalian TGF-b receptor interacting protein. Plant J 43: 251-261<br /> <br /> Eide D, Gehl M, Nair M, Gribskov M, Guerinot M, Harper JF (2005) Characterization of the yeast ionome; a genome-wide analysis of nutrient mineral and trace element homeostasis in Saccharomyces cerevisiae. Genome Biol 6: R77<br /> <br /> Ercetin ME, Gillaspy GE (2004) Molecular characterization of an Arabidopsis phospholipid-specific inositol polyphosphate 5-phosphatase. Plant Physiol 135: 938-946 <br /> <br /> Gao Z, Jayanty S, Beaudry R, Loescher W (2005) Watercore and sorbitol transporters in apple sink tissues: implications for fruit sugar accumulation and watercore development. J Amer Soc Hort Sci 130: 2:261-268<br /> <br /> Gao Z, Loescher WH (2003) Expression of a celery mannose 6-phosphate reductase in Arabidopsis thaliana enhances salt tolerance and induces biosynthesis of both mannitol and a glucosyl-mannitol dimer. Plant Cell Environ 26: 275-283<br /> <br /> Gao Z, Maurousset L, Lemoine R, Yoo S-D, van Nocker S, Loescher W (2003) Cloning, expression, and characterization of sorbitol transporters from developing sour cherry (Prunus cerasus) fruit and leaf sink tissues. Plant Physiol 131: 1566-1575<br /> <br /> Gehrig HH, Wood J, Cushman MA, Virgo A, Cushman JC, Winter K (2005) Large gene family of phosphoenolpyruvate carboxylase in the crassulacean acid metabolism plant Kalanchoe pinnata (Crassulaceae). Functional Plant Biol 32: 467-472<br /> <br /> Gillaspy GE, Ercetin ME, Burnette RN (2004) Inositol metabolism in plant cells: a genomics perspective, In Hemantaranjan A, ed, Advances in Plant Physiology, Volume 7. India, pp 145-158 <br /> <br /> Gong Q, Li P, Ma S, Rupassara SI, Bohnert HJ (2005) Stress adaptation competence in Arabidopsis thaliana and its extremophile relative Thellungiella halophila. Plant J, In press<br /> <br /> Harper JF, Harmon A (2005) Plants, symbiosis and parasites: a Ca2+-signalling connection. Nature Rev Mol Cell Biol 6: 555-566<br /> <br /> Heaton E, Voigt T, Long SP (2004) A quantitative review comparing the yields of two candidate C-4 perennial biomass crops in relation to nitrogen, temperature and water. Biomass Bioenergy 27: 21-30<br /> <br /> Hwang S-K, Salamone PR, Okita TW (2005) The higher plant ADP-glucose pyrophosphorylase subunits modulate the regulatory and catalytic properties through their synergistic interactions. FEBS Lett 579: 983-9<br /> <br /> Hwang S-K, Salamone PR, Kavakli H, Slattery CJ, Okita TW (2004) Rapid purification of the potato ADP-glucose pyrophosphorylase by poly-histidine mediated chromatography. Protein Purif Express 38: 99-107<br /> <br /> Ivanov B, Asada K, Kramer D, Edwards GE (2005) Characterization of photosynthetic electron transport in bundle sheath cells of maize. Ascorbate can effectively charge cyclic electron flow. Planta 220: 572-581<br /> <br /> Jin X, Ballicora MA, Preiss J, Geiger JH(2005) Crystal structure of potato tuber ADP-glucose pyrophosphorylase. Embo J 24: 694-704<br /> <br /> Karkehabadi S, Taylor T C, Spreitzer RJ, Andersson I (2005) Altered intersubunit interactions in crystal structures of catalytically-compromised ribulose-1,5-bisphosphate carboxylase/oxygenase. Biochemistry 44: 13-120<br /> <br /> Karkehabadi S, Peddi SR, Anwaruzzaman M, Taylor TC, Cederlund A, Genkov T, Andersson I, Spreitzer RJ (2005) Chimeric small subunits influence catalysis without causing global conformational changes in the crystal structure of ribulose-1,5-bisphosphate carboxylase/oxygenase. Biochemistry 44: 9851-9861<br /> <br /> Kim K, Portis AR Jr (2005) Temperature dependence of photosynthesis in Arabidopsis plants with modifications in Rubisco activase and membrane fluidity. Plant Cell Physiol 46: 522-530<br /> <br /> Kim K, Portis AR Jr (2005) Kinetic analysis of the slow inactivation of Rubisco during catalysis: Effects of temperature, O2 and Mg++. Photosyn Res, In press<br /> <br /> Kore-eda S, Noake C, Ohishi M, Ohnishi J, Cushman JC (2005) Transcriptional regulation of organellar metabolite transporters during induction of crassulacean acid metabolism in Mesembryanthemum crystallinum. Functional Plant Biol 32: 451-466<br /> <br /> Kramer DM, Kanazawa A, Cruz JA, Ivanov B, Edwards GE (2005) The relationship between photosynthetic electron transfer and its regulation. In Papageorgiou GC, Govindjee, eds, Chlorophyll a Fluorescence: A Signature of Photosynthesis. Springer, New York, NY. pp 251-278<br /> <br /> Leakey ADB, Bernacchi CJ, Dohleman FG, Ort DR, Long SP (2004) Will photosynthesis of maize (Zea mays) in the US corn belt increase in future CO2 rich atmospheres? An analysis of diurnal courses of CO2 uptake under free-air concentration enrichment (FACE). Global Change Biol 10: 951-962<br /> <br /> Li C, Salvucci ME, Portis AR Jr (2005) Two residues of Rubisco activase involved in recognition of the Rubisco substrate. J Biol Chem 280: 24864-24869<br /> <br /> Li J-H, Guiltinan MJ, Thompson DB (2005) The use of laser differential interference contrast microscopy for the characterization of starch granule ring structure. Starch/Starke, In press<br /> <br /> Li P, Mane SP, Sioson AA, Heath LS, Bohnert HJ, Grene R (2005) Effects of chronic ozone exposure on gene expression in Arabidopsis thaliana ecotypes and in Thellungiella halophila. Plant Cell Environ, In press <br /> <br /> Li P, Sioson AA, Mane SP, Ulanov A, Grothaus G, Heath LS, Murali TM, Bohnert HJ, Grene R (2006) Arabidopsis thaliana ecotypes and Thellungiella halophila grown in FACE rings  Response diversity and signature genes in elevated CO2. Plant J, revised, submitted<br /> <br /> Loescher W, Johnson T, Beaudry R, Jayanty S (2005) Sorbitol transport, sorbitol, and watercore in apple cultivars differing in watercore susceptibility. HortScience 40: 993-994<br /> <br /> Long SP, Ainsworth EA, Rogers A, Ort DR (2004) Rising atmospheric carbon dioxide: Plants face the future. Annu Rev Plant Biol 55: 591-628<br /> <br /> Lynnette M, Dirk A, Trievel RC, Houtz RL (2005) Non-histone protein lysine methyltransferases - structure and catalytic roles. In Tamanoi F, Clarke S, eds, Protein Methyltransferases. The Enzymes. Academic Press, In press<br /> <br /> Ma S, Quist T, Ulanov A, Quigley F, Joly R, Bohnert HJ (2004) Suppression of gTIP in Arabidopsis leads to cell and plant death. Plant J 40: 845-859 <br /> <br /> Mamedov TG, Moellering ER, Chollet R (2005) Identification and expression analysis of two genes encoding novel and distinct molecular forms of eukaryotic PEP carboxylase in the green microalga Chlamydomonas reinhardtii. Plant J 42: 832-843<br /> <br /> Maricle BR, Kiirats O, Edwards GE, Lee R (2005) Effects of salinity on photosynthesis in C4 estuarine grasses. In Proceedings of the Third International Conference on Invasive Spartina. Cambridge Publications, In press<br /> <br /> McCarty DR, Settles AM, Suzuki M, Tan BC, Latshaw S, Porch T, Robin K, Baier J, Avigne W T, Lai J, Messing J, Koch KE, Hannah LC (2005) Steady-state transposon mutagenesis in inbred maize. Plant J 44: 52-61<br /> <br /> Mittler R (2005) Abiotic stress, the field environment and stress combination. Trends Plant Sci, In press<br /> <br /> Mittler R, Vanderauwera S, Gollery M, Van Breusegem F (2004) The reactive oxygen gene network of plants. Trends Plant Sci 9: 490-498<br /> <br /> Miyazaki S, Fredricksen M, Hollis KC, Poroyko V, Shepley D, Galbraith DW, Long SP, Bohnert HJ (2004) Transcript expression profiles of Arabidopsis thaliana grown under controlled conditions and open-air elevated concentrations of CO2 and of O3. Field Crops Res 90: 47-59<br /> <br /> Morgan PB, Bernacchi CJ, Ort DR, Long SP (2004) An in vivo analysis of the effect of season-long open-air elevation of ozone to anticipated 2050 levels on photosynthesis in soybean. Plant Physiol 135: 2348-2357<br /> <br /> Morgan PB, Bollero GA, Nelson RL, Dohleman FG, Long SP (2005) Smaller than predicted increase in aboveground net primary production and yield of field-grown soybean under fully open-air CO2 elevation. Global Change Biol 11: 1856-1865<br /> <br /> Naidu SL, Long SP (2004) Potential mechanisms of low-temperature tolerance of C-4 photosynthesis in Miscanthus x giganteus: an in vivo analysis. Planta 220: 145-155<br /> <br /> Obana Y, Omoto D, Kato C, Matsumoto K, Nagai Y, Kavakli IH, Hamada S, Edwards GE, Okita TW, Matsui H, Ito H (2006) Enhanced turnover of transitory starch by expression of up-regulated ADP-glucose pyrophosphorylases in Arabidopsis thaliana. Plant Sci 170:1-11<br /> <br /> Peddi SR, Karkehabadi S, Anwaruzzaman M, Andersson I, Spreitzer RJ (2005) Evolutionary divergence in the structure of the small-subunit ²A-²B loop of ribulose-1,5-bisphosphate carboxylase/oxygenase is not essential for assembly but influences large-subunit catalysis. In van der Est A, Bruce D, eds, Photosynthesis: Fundamental Aspects to Global Perspectives. Allen Press, Lawrence, Kansas, pp 828-830<br /> <br /> Pimentel C, Davey PA, Juvik JA, Long SP (2005) Gene loci in maize influencing susceptibility to chilling dependent photoinhibition of photosynthesis. Photosyn Res 85: 319-326<br /> <br /> Platten DJ, Cotsaftis O, Berthomieu P, Bohnert H, Davenport RJ, Fairbairn DJ, Horie T, Leigh R, Lin H-X, Luan S, Mäser P, Pantoja O, Rodríguez-Navarro A, Rus A, Schachtman DP, Schroeder JI, Sentenac H, Uozumi N, Véry A-A, Zhu J-K, Dennis ES, Tester M (2006) Nomenclature for HKT genes, central for plant salinity tolerance. Science (nomenclature section)<br /> <br /> Poroyko V, Hejlec LG, Spollen W, Springer G, Nguyen HT, Sharp R, Bohnert HJ (2005) The maize root transcriptome by serial analysis of gene expression. Plant Physiol 138: 1700-1710<br /> <br /> Preiss J (2004) Plant starch synthesis. In Eliasson A-C,ed, Starch in Food, Structure, Function and Applications. CRC Press and Woodhead Publishing Ltd, Cambridge, UK, pp 3-56Yoo S-D, Gao Z, Cantini C, Loescher W, van Nocker S (2003) Fruit ripening in sour cherry (Prunus cerasus): changes in expression of genes expressing expansins and other cell-wall-modifying enzymes. J Amer Soc Hort Sci 128: 16-22<br /> <br /> Rogers A, Allen DJ, Davey PA, Morgan PB, Ainsworth EA, Bernacchi CJ, Cornic G, Dermody O, Dohleman FG, Heaton EA, Mahoney J, Zhu XG, Delucia EH, Ort DR, Long SP (2004) Leaf photosynthesis and carbohydrate dynamics of soybeans grown throughout their life-cycle under Free-Air Carbon dioxide Enrichment. Plant Cell Environ 27: 449-458<br /> <br /> Rolletschek H, Koch K, Wobus U, Borisjuk L (2005) Positional cues for the starch/lipid balance in maize kernels and resource partitioning to the embryo. Plant J 42: 69-83 [cover article]<br /> <br /> Sakusingharoj C, Choi S-B, Hwang S-K, Bork J, Meyer CR, Edwards GE, Preiss J, Okita TW (2004) Engineering starch biosynthesis for enhanced rice yields: the role of the cytoplasmic ADP-glucose pyrophosphorylase. Plant Sci 167: 1323-1333<br /> <br /> Salvucci ME (2004) Potential for interactions between the carboxy and amino termini of Rubisco activase subunits FEBS Lett 560: 205-209<br /> <br /> Salvucci ME, Crafts-Brandner SJ (2004) Inhibition of photosynthesis by heat stress: the activation state of Rubisco as a limiting factor in photosynthesis. Physiol Plant 120: 179-186<br /> <br /> Salvucci ME, Crafts-Brandner SJ (2004) Mechanism for deactivation of Rubisco under moderate heat stress. Physiol Plant 122: 513-519<br /> <br /> Salvucci ME, Crafts-Brandner SJ (2004) Relationship between the heat tolerance of photosynthesis and the thermal stability of Rubisco activase in plant from contrasting thermal environments. Plant Physiol 134: 1460-1470<br /> <br /> Sebastia CH, Marsolais F, Saravitz C, Israel DW, Dewey R, Huber SC (2005) Metabolic profiles of free amino acids suggests a possible role for Asn in the control of storage product accumulation in developing soybean seeds. J Exp Bot 56: 1951-1963<br /> <br /> Seebauer JR, Moose SP, Fabbri BJ, Crossland LD, Below FE (2004) Amino acid metabolism in maize earshoots: Implications for assimilate preconditioning and nitrogen signaling. Plant Physiol 136: 4326-4334 <br /> <br /> Shao M, Zheng H, Hu Y, Liu D, Jang, J-C, Ma H, Huang H (2004) The GAOLAOZHUANGREN1 gene encodes a putative glycosyltransferase that is required for normal development and affects sink-source transition in Arabidopsis. Plant Cell Physiol 45: 1453-1460<br /> <br /> Sharp RE, Poroyko V, Hejlek LG, Spollen WG, Springer GK, Bohnert HJ, Nguyen HT (2004) Root growth maintenance during water deficits: physiology to functional genomics. J Exp Bot 55: 2343-2351<br /> <br /> Shepherd RW, Bass WT, Houtz RL, Wagner GJ (2005) Phylloplanins of tobacco are defensive proteins deployed on aerial surfaces by short glandular trichomes. Plant Cell 17: 1851-186<br /> <br /> Sioson AA, Mane SP, Sha W, Li P, Heath LS, Bohnert HJ, Grene R (2005) The TM4 microarray analysis software suite and the two-step ANOVA mixed model analysis method for the detection of significantly expressed genes; a comparison. Bioinformatics, In press<br /> <br /> Spreitzer RJ, Peddi SR, Satagopan S (2005) Phylogenetic engineering at an interface between large and small subunits imparts land-plant kinetic properties to algal ribulose-1,5-bisphosphate carboxylase/oxygenase. Proc Natl Acad Sci USA 102, In press<br /> <br /> Styer J, Spence J, Keddie J, Gillaspy GE (2004) Genomic organization and regulation of the Leimp-1 and Leimp-2 genes encoding myo-inositol monophosphatase in tomato. Gene 326: 35-41<br /> <br /> Suzuki N, Mittler R (2005) Reactive oxygen and temperature stress. Physiol Plant, In press<br /> <br /> Suzuki N, Rizhsky L, Liang H, Shuman J, Shulaev V, Mittler R (2005) Enhanced tolerance to environmental stress in transgenic plants expressing the transcriptional co-activator MBF1. Plant Physiol, In press<br /> <br /> Tang G-Q, Novitzky B, Griffin C, Huber SC, Dewey R (2005) Functional characterization of two closely related soybean (Glycine max) oleate desaturase enzymes: evidence of regulation through differential stability and phosphorylation. Plant J 44: 433-446<br /> <br /> Torabinejad J, Gillaspy GE (2005) Functional genomics of inositol metabolism. In Biswas, Majumder, eds, Subcellular Biochemistry, Vol 39, Biology of Inositols and Phosphoinositide. In press<br /> <br /> Tovar-Mendez, A, Hirani TA, Miernyk JA, Randall DD (2005). Analysis of the catalytic mechanism of pyruvate dehydrogenase kinase. Arch Biochem Biophys 434: 159-168<br /> <br /> Price J, Laxmi A, St Martin SK, Jang, J-C (2004) Global transcription profiling reveals multiple sugar signal transduction mechanisms in Arabidopsis. Plant Cell 16: 2128-2150<br /> <br /> Uribelarrea M, Moose SP, Below FE (2005) Divergent selection for grain protein affects nitrogen use in maize hybrids. Field Crops Res, In press<br /> <br /> Voznesenskaya EV, Chuong SDX, Kiirats O, Franceschi VR, Edwards GE (2005) Evidence that C4 species in genus Stipagrostis, family Poaceae, is NADP-malic enzyme subtype with nonclassical type of Kranz anatomy (Stipagrostoid). Plant Sci 168: 731-739<br /> <br /> Voznesenskaya EV, Choung SDX, Koteyeva NK, Edwards GE, Franceschi VR (2005) Functional compartmentation of C4 photosynthesis in the triple-layered chlorenchyma of Aristida (Poaceae). Functional Plant Biol 32: 67-77<br /> <br /> Voznesenskaya EV, Koteyeva NK, Chuong SDX, Edwards GE, Akhani H, Franceschi VR (2005) Differentiation of cellular and biochemical features of the single cell C4 syndrome during leaf development in Bienertia cycloptera (Chenopodiaceae). Am J Bot 92: 1784-1795 [article highlighted on cover page of issue] <br /> <br /> Wang XF, Goshe MB, Soderlom E, Phinney BS, Kuchar J, Li J, Asami T, Yoshida S, Huber SC, Clouse SD (2005) Identification and functional analysis of in vivo phosphorylation sites of the Arabidopsis BRASSINOSTEROID-INSENSITIVE 1 receptor kinase. Plant Cell 17: 1685-1703<br /> <br /> Wittig VE, Bernacchi CJ, Zhu XG, Calfapietra C, Ceulemans R, Deangelis P, Gielen B, Miglietta F, Morgan PB, Long SP (2005) Gross primary production is stimulated for three Populus species grown under free-air CO2 enrichment from planting through canopy closure. Global Change Biol 11: 644-656<br /> <br /> Xiang P, Haas EJ, Zeece MG, Markwell J, Sarath G (2004) C-terminal 23 kDa polypeptide of soybean Gly m Bd 28 K is a potential allergen. Planta 220: 56-63<br /> <br /> Yao Y, Thompson DB, Guiltinan MJ (2004) Maize starch branching enzyme (SBE) isoforms and amylopectin structure: in the absence of SBEIIb, the further absence of SBEIa leads to increased branching. Plant Physiol 136: 3515-3523<br /> <br /> Yong W, Link B, OMalley R, Tewari J, Hunter CT III, Lu C-A, Li X, Bleecker AB, Koch KE, McCann MC, McCarty DR, Patterson SE, Reiter W-D, Staiger C, Thomas SR, Vermerris W, Carpita NC (2005) Genomics of plant cell wall biogenesis. Planta 221: 747-571<br /> <br /> Yuan Y, Guiltinan MJ, Thompson DB (2005) High-performance size-exclusion chromatography (HPSEC) and fluorophore-assisted carbohydrate electrophoresis (FACE) to describe the chain-length distribution of debranched starch. Carbohydr Res 340: 701-710<br /> <br /> Zhu XG, Ort DR, Whitmarsh J, Long SP (2004) The slow reversibility of photosystem II thermal energy dissipation on transfer from high to low light may cause large losses in carbon gain by crop canopies: a theoretical analysis. J Exp Bot 55: 1167-1175<br /> <br /> Zhu XG, Portis AR, Long SP (2004) Would transformation of C-3 crop plants with foreign Rubisco increase productivity? A computational analysis extrapolating from kinetic properties to canopy photosynthesis. Plant Cell Environ 27: 155-165<br /> <br /> <br />

Impact Statements

1. Work presented here addresses central aspects of US agriculture and especially demands for food, fiber, and bioenergy. Increases in quality and quantity of agricultural productivity will depend on new approaches to multiple aspects of primary productivity (photosynthesis), how these resources are utilized in the plant (partitioning to harvestable products), and how these processes can be maximized under adverse environmental conditions. Additional relevance of the work is in its importance to reducing global CO2 levels via photosynthetic activity, and in appraising crop responses to global change. The NC-1-142 group is uniquely poised to address these areas.
2. Fundamental studies of processes controlling primary reactions of photosynthesis can lead to strategies for enhancing and/or stabilizing their action. One of these (described in this year&lsquo;s report) indicates that transgenically enhanced capacity for starch deposition and turnover can increase photosynthetic rates by affecting initial photoreactions (evident through chlorophyll fluorescence and cyclic electron flow). Data thus far indicate that this change also translates into more rapid plant growth.
3. Several approaches have been pursued for enhancing effectiveness of photosynthetic CO2 assimilation. This has been a notoriously2. Several approaches have been pursued for enhancing effectiveness of photosynthetic CO2 assimilation. This has been a notoriously difficult area, but successes include progress on chloroplast transformation and new approaches to engineering the RuBISCO enzyme. difficult area, but successes include progress on chloroplast transformation and new approaches to engineering the RuBISCO enzyme.
4. Progress on several fronts has advanced our understanding of how photosynthetic resources are partitioned between growth, development, and harvestable plant products. This year, for example, we have found that the extent and quality of photosynthate partitioning to cell wall biomass can be altered by subtly changing aspects of enzymes that metabolize sucrose (the long-distance transport sugar in plants).
5. A formidable impediment to agricultural productivity in the US and elsewhere is the reduction in photosynthesis by environmental stresses. Results from this years efforts by the NC-1-142 group ranged from developing models for predicting extent of stress damage, to testing engineered plants with enhanced resistance to them. Of particular interest have been the gene networks regulating plant responses to stresses, so that these can be manipulated to aid resistance.

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Report Information

Participants

Robert Aiken (KS-AES), Fred Below (IL-AES), Hans Bohnert (IL-AES), Ray Chollet (NE-AES), John Cushman (NV-AES), Larry Daley (OR-AES), Stan Duke (WI-AES), Gerald Edwards (WA-AES), Mark Guiltinan PA-AES), Jeff Harper (NV-AES), Robert Houtz (KY-AES), S.C. Huber (IL-ARS, Urbana), Robert Jones (MN-AES), Allen D. Knapp (IA-AES), Al K. Knapp (KS-AES), Karen Koch (FL-AES), Wayne Loescher (MI -AES), Steve Long (IL-AES), Ron Mittler (NV-AES), Brandon Moore (SC-AES), Tom Okita (WA-AES), Archie Portis (IL-ARS, Urbana), Jack Preiss (MI-AES), Doug Randall (MO-AES), Steve Rodermel (IA-AES), Robert Spreitzer (NE-AES), Glenda Gillaspy (VA-AES), Michael Salvucci (AZ-ARS), Jyan-Chyun Jang (OH-AES),

Brief Summary of Minutes

Annual Meeting Date and Location: November 11, 2006 Kentucky AES host, University of Kentucky Student Union Building

Attending Members: Dr. Robert Houtz Kentucky AES, Dr. Steve Rodermel Iowa AES, Dr. Robert Spreitzer Nebraska AES, Dr. Larry Daley Oregon AES, Dr. Brandon Moore South Carolina AES, Dr. John Cushman Nevada AES, Dr. Glenda Gillaspy Virginia AES, Dr. Jyan-Chyun Jang Ohio AES, Dr. Tom Okita Washington AES, Dr. Archie Portis Illinois ARS, Dr. Steve Rodermel Iowa AES.

Attending Guests Interested in NC-1-142 Membership: Dr. Vara Prassas Kanas AES
Non-Attending Guests Interested in NC-1142 Membership: Dr. Mary E. Rumpho-Kennedy Maine AES, Donald P. Weeks Nebraska AES, Dr. Martin H. Spalding Iowa AES, Dr. David M. Kramer Washington AES.

This year's meeting was called to order by Dr. Robert Houtz, Chair. Participants each gave a 25 min overview of their previous years accomplishments, with questions and comments following each presentation. The talks also included many informal discussions between talks, at breaks, and during lunch. Inclement weather conditions, particularly in the Chicago area delayed the arrival of some members and completely prevented attendance by our AR, Dr. Irwin Goldman.
Most discussions addressed the necessity for NC-1142 project renewal, as well as several other needs such as impact statements and the impending retirement of several individuals. Overall the quality of the science was impressive to all participants and generally there was a large amount of enthusiasm for the NC-1142 group.

The business meeting was called to order after the talks. The meeting was attended by all members listed and lasted about 90 min. The primary issues were to 1) discuss candidates for incoming membership, 2) appoint new officers, 3) discuss impending retirements and possible replacements, as well as recruitment efforts, and 4) decide on who would assist in the preparation of the renewal request. Several individuals volunteered to contribute according to areas of research according to Objectives. The only new member voted on was Dr. Mary E. Rumpho-Kennedy, who received unanimous support. It was noted that although the NC-1142 members have in the past decided on membership, technically this was in the hands of local administrators.

New officers were selected with Dr. Mike Salvucci as vice-chair, Dr. Robert Spreitzer as Chair, and Dr. Glenda Gillaspy as secretary. The group agreed to maintain the current relative meeting date, 2 weekends before Thanksgiving, and keep the meetings on campus.

Key discussions at the meeting: These centered on the science outlined in reports from the attending AES/ARS representatives, the visiting candidates for new membership, and mainly concerns about the project renewal request.
Assigned responsibilities: As decided by NC-1142 participants, the leadership succession will progress from Dr. Robert Houtz (Kentucky AES), departing Chair of the 2006 meeting, to Dr. Robert Spreitzer (Nebraska AES) incoming Chair and host for the 2007 meeting. Dr. Mike Salvucci will become vice-chair and will host the 2008 meeting. Dr. Glenda Gillaspy will serve as secretary for the 2007 meeting.

Accomplishments

See attachment with minutes.

Publications

Aiken RM, Lamm FR (2006) Irrigation guidelines for oilseed crops in the U.S. central great plains. Tech Conf Proc 27th Ann Irrig Assoc. IA06-14581480<br /> <br /> Aluru M, Guo R, Xu Y, Wang K, Wang Z, Li S, Alsheikh M, White W, Rodermel S (2006) Generation of transgenic maize with enhanced provitamin A content. Proc Natl Acad Sci USA, In press <br /> <br /> Aluru MR, Yu F, Fu A, Rodermel S (2006) Arabidopsis variegation mutants: new insights into chloroplast biogenesis. J Exp Bot 57: 1871-1881 (Refereed review)<br /> <br /> Aluru MR, Stessman DJ, Spalding MH, Rodermel SR (2006) Alterations in photosynthesis in Arabidopsis lacking IMMUTANS, a chloroplast terminal oxidase. Photosyn Res, In press<br /> <br /> Alsheikh M, Rodermel S (2005) Genetics and genomics of chloroplast biogenesis. Maydica 50: 443-449. (Invited review: 50th anniversary of Maydica)<br /> <br /> Baerr JN, Thomas JD, Taylor BG, Rodermel SR, Gray GR (2005) Differential photosynthetic compensatory mechanisms exist in the immutans mutant of Arabidopsis thaliana. Physiol Plant 124: 390-402 (Cover article)<br /> <br /> Balasubramanian R, Karve A, Kandasamy M, Meagher RB, Moore Bd (2007) A role for F-actin in hexokinase mediated glucose signaling. Plant J, In revision <br /> <br /> Barkan L, Evans MA, Edwards GE (2007) Increasing UV-B induces biphasic leaf cell expansion in Phaseolus vulgaris, suggesting multiple mechanisms for controlling plant growth. Photochem Photobiol, In press<br /> <br /> Bejar C, Ballicora MA, Iglesias AA, Preiss J (2006) ADP-glucose pyrophosphorylase's N-terminus: structural role in allosteric regulation. Biochem Biophys Res Comm 343: 216-221<br /> <br /> Bejar CM, Ballicora MA, Preiss J (2006) Molecular architecture of the glucose1-phosphate site in ADP-glucose pyrophosphorylases. J Biol Chem, In press<br /> <br /> Bohnert HJ (2007) Abiotic stress. In: Roberts R, ed, Encyclopedia of Life Sciences. John Wiley & Sons, Chichester, UK, In press <br /> <br /> Bohnert HJ, Bressan RA, Hasegawa PM (2005) Ion homeostasis and water deficit. In: Ribaut JM, Drought Tolerance in Cereals. Haworth Press, New York, pp 551-582<br /> <br /> Bohnert HJ, Gong Q, Li P, Ma S (2006) Unravelling abiotic stress tolerance mechanisms  getting genomic going. Curr Opin Plant Biol 9: 180-188 <br /> <br /> Borland AM, Elliott S, Pater B, Taybi T, Cushman JC, Barnes B (2006) Is Crassulacean acid metabolism a consequence or cause of oxidative stress? J Exp Bot 57: 319-328<br /> <br /> Boyd CN, Franceschi VR, Chuong SDX, Akhani H, Kiirats O, Smith M, Edwards GE (2007) Chlorenchyma tissue in flowers and stems of Bienertia cycloptera and flowers of Suaeda arolcaspica (Chenopodiaceae) exhibit single cell C4 photosynthesis. Special Issue in Memory of Vincent R. Franceschi. Functonal Plant Biol, Submitted<br /> <br /> Bressan RA, Bohnert HJ, Hasegawa PM (2005) Bioengineering for plant abiotic stress tolerance. In: Nguyen H, Bohnert HJ, eds, Engineering of Plant Metabolic Pathways. Elsevier, Netherlands, In press <br /> <br /> <br /> Burey SC, Poroyko V, Ozturk N, S. Fathi-Nejad S, Hammerschmied G, Schueller C, Steiner JM, Bohnert HJ, Loeffelhardt W (2005) Response to low carbon dioxide in the glaucocystophyte alga, Cyanophora paradoxa. Proc Intl Congr Photosyn, Canada<br /> <br /> Chehab EW, Patharkar OR, Cushman JC (2006) Isolation and characterization of a novel trafficking protein for calcium-dependent protein kinase 1 from Mesembryanthemum crystallinum. Planta, In press<br /> <br /> Chuong SDX, Franceschi VR, Edwards GE (2006) Two unique patterns of organelle partitioning required for C4 photosynthesis in a single cell are maintained by the cytoskeleton in family Chenopodiaceae. Plant Cell 18: 2207-2223<br /> <br /> Cramer GR, Ergül A, Grimplet J, Tillett RL, Tattersall EAR, Bohlman MC, Vincent D, Sonderegger J, Evans J, Osborne C, Quilici D, Schlauch KA, Schooley DA, Cushman JC (2006) Transcript and metabolite profiling of grapevines exposed to gradually increasing, long-term water-deficit or isoosmotic salinity. Funct Int Gen, In press<br /> <br /> Dirk LMA, Trievel RC, Houtz RL (2006) In: Tamanoi F, Clarke S, eds, The Enzymes Vol. 24. Elsevier Academic Press, Burlington, MA, pp. 179-229<br /> <br /> Dyachenko OV, Zakharchenko NS, Shevchuk TV, Bohnert HJ, Cushman JC, Buryanov Ya A (2006) Effect of hypermethylation of CCWGG sequences in DNA of Mesembryanthemum crystallinum plants on their adaptation to salt stress. Biokhimiya/ Biochemistry (Moscow) 71: 461-465<br /> <br /> Edwards GE, Voznesenskaya E, Smith M, Koteyeva N, Park Y, Park J-H, Kiirats O, Okita TW, Chuong SDX (2007) Breaking the Kranz paradigm in terrestrial C4 plants: Does it hold promise for C4 rice? In: Sheehy JE, Mitchell PL, Hardy B, eds, Proceedings of the 2006 meeting of the C4 Rice Consortium (International Rice Research Institute, Makati City, Philippines. In press<br /> <br /> Fu A, Park S, Rodermel S (2005) Sequences required for the activity of PTOX (IMMUTANS), a plastid terminal oxidase: in vitro and in planta mutagenesis of iron-binding sites and a conserved sequence that corresponds to Exon 8. J Biol Chem 280: 42489-42496. (Cover article)<br /> <br /> Genkov T, Du YC, Spreitzer RJ (2006) Small-subunit cysteine-65 substitutions can suppress or induce alterations in the large-subunit catalytic efficiency and holoenzyme thermal stability of ribulose-1,5-bisphosphate carboxylase/oxygenase. Arch Biochem Biophys 451: 167-174<br /> <br /> Gollery M, Harper J, Cushman J, Mittler T, Girke T, Zhu J-K, Bailey-Serres J, Mittler R (2006) What Makes Species Unique? A Role for Genes with Unknown Function. Gen Res 7:R57<br /> <br /> Gong Q, Li P, Ma S, Rupassara SI, Bohnert HJ (2005) Stress adaptation competence in Arabidopsis thaliana and its extremophile relative Thellungiella halophila. Plant J 44: 826-839<br /> <br /> Grimplet J, Deluc LG, Cramer GR, Cushman JC (2006) Integrating functional genomics with salinity and water-defict stress responses in wine grape  Vitis vinifera. In: Jenks MA, Hasegawa PM, Jain SM, eds, Advances in molecular-breeding toward drought and salt tolerant crops. Springer, Dordrecht, The Netherlands<br /> <br /> <br /> Gunesekera B, Torabinejad T, Robinson J, Gillaspy G. Inositol (2007) Polyphosphate 5-phosphatases 1 and 2 are required for regulating seedling growth. Plant Physiol, In revision<br /> <br /> Hegeman AD, Rodriguez-Milla MA, Han BW, Uno Y, Phillips Jr. GN, Hrabek EM, Cushman JC, Harper JF, Harmon AC, Sussman MR (2006) Conserved autophosphorylation loci mapped across multiple calcium-dependent protein kinase isoforms. Proteomics 6: 3649-3664<br /> <br /> Huang L-F, Bocock PN, Davis JM, Koch KE (2007) Invertase regulation: A suite of transcriptional and post-transcriptional mechanisms. Funct Plant Biol, In press<br /> <br /> Iglesias AA, Ballicora MA, Sesma JI, Preiss J (2006) Domain swapping between a cyanobacterial and a plant subunit ADPG-pyrophosphorylase. Plant Cell Physiol 47:523-530<br /> <br /> Iturriaga, G, Cushman MAF, Cushman JC (2006) An EST catalogue from the resurrection plant Selaginella lepidophylla reveals stress-adaptive genes. Plant Sci170: 1173-1184<br /> <br /> Kapralov MV, Akhani H, Voznesenskaya EV, Edwards G, Franceschi V, Roalson E (2006) Phylogenetic relationships in the Salicornioideae /Suaedoideae /Salsoloideae s.l. (Chenopodiaceae) clade and a clarification of the phylogenetic position of Bienertia and Alexandra using multiple DNA sequence datasets. Systematic Bot 31: 571-585<br /> <br /> Kohorn B, Kobayashi M, Johansen S, Riese J, Huang L-F, Koch K, Dotson A, Byers N (2006) An Arabidopsis cell wall associated kinase required for invertase activity and cell growth. Plant J 46: 307-316<br /> <br /> Lara MV, Chuong SDX, Akhani H, Andreo CS, Edwards GE (2006) Species having C4 single cell type photosynthesis in family Chenopodiaceae evolved a photosynthetic phosphoenolpyruvate carboxylase like that of C4 Kranz type species. Plant Physiol 142: 673-684<br /> <br /> Li C, Wang D, Portis AR Jr. (2006) Identification of critical arginine residues in the functioning of Rubisco activase. Arch Biochem Biophys 450: 176-182<br /> <br /> Li J, Guiltinan MJ, Thompson DB (2006) The use of laser differential interference contrast microscopy for the characterization of starch granule ring structure. Starch/Starke 58:1-5<br /> <br /> Li P, Mane SP, Sioson AA, Heath LS, Bohnert HJ, Grene R (2005) Effects of chronic ozone exposure on gene expression in Arabidopsis thaliana ecotypes and in Thellungiella halophila. Plant Cell Environ 29: 854-868 <br /> <br /> Li P, Sioson AA, Mane SP, Ulanov A, Grothaus G, Heath LS, Murali TM, Bohnert HJ, Grene R (2006) Response diversity of Arabidopsis thaliana ecotypes in elevated [CO2] in the field. Plant Mol Biol 62: 593-609<br /> <br /> Ma S, Gong Q, Bohnert HJ (2005) Dissecting salt stress pathways. J Exp Bot 57: 1097-1107<br /> <br /> Maricle BR, Kiirats O, Edwards GE, Lee R (2007) Effects of salinity on photosynthesis in C4 estuarine grasses. In: Proceedings of the Third International Conference on Invasive Spartina. Cambridge Publications. In press<br /> <br /> Obana Y, Omoto D, Kato C, Matsumoto K, Nagai Y, Kavakli IH, Hamada S, Edwards GE, Okita TW, Matsui H, Ito H (2006) Enhanced turnover of transitory starch by expression of up-regulated ADP-glucose pyrophosphorylases in Arabidopsis thaliana. Plant Sci170:1-11<br /> <br /> Patharkar OR, Cushman JC (2006) A novel coiled-coil protein serves as a putative adapter protein during stress-induced localization changes of a calcium dependent-protein kinase in the common ice plant. Planta, In press<br /> <br /> Platten JD, Cotsaftis O, Berthomieu P, Bohnert H, Davenport RJ, Fairbairn DJ, Horie T, Leigh RA, Lin H-X, Luan S, Mäser P, Pantoja O, Rodríguez-Navarro A, Schachtman DP, Schroeder JI, Sentenac H, Uozumi N, VéryA-A, Zhu J-K, Dennis ES, Tester M (2006) Nomenclature for HKT transporters, key determinants of plant salinity tolerance. Trends Plant Sci 11: 372-374<br /> <br /> Poroyko V, Spollen W, Hejlik LG, Hernandez AG, LeNoble M, Davis G, Nguyen HT, Springer GK, Sharp RE, Bohnert HJ (2006) Regional transcript profiles from well-watered and water-stressed maize primary roots. J Exp Bot, In press<br /> <br /> Prather BL, Widhalm JR, Markwell J, Herman PL (200X) Development of a system for directed evolution of Arabidopsis formate dehydrogenase to utilize NADP as a cofactor. Rev Undergrad Res Agric Life Sci, In press<br /> <br /> Preiss J (2006) Bacterial glycogen inclusions: enzymology and regulation of synthesis. In: Shively JM, ed, Microbiology Monographs Vol. 1. Springer, Heidelberg, Germany, pp 71-108<br /> <br /> Rodermel S, Viret J-F, Krebbers E (2005) Lawrence Bogorad (1921-2003), a pioneer in photosynthesis research: a tribute. Photosyn Res 83: 17-24 (Invited tribute)<br /> <br /> Rodriguez Milla MA, Townsend J, Chang I-F, Cushman JC (2006) The Arabidopsis AtDi-19 gene family encodes a novel type of Cys2/His2 zinc-finger protein implicated in ABA-independent dehydration, high-salinity stress and light signaling pathways. Plant Mol Biol 61: 13-30<br /> <br /> Rodriguez Milla MA, Uno Y, Townsend J, Maher E, Cushman JC (2006) Arabidopsis AtCPK11, a calcium-dependent protein kinase, phosphorylates AtDi19, a nuclear zinc finger protein. FEBS Lett 580: 904-911<br /> <br /> Rosso D, Ivanov AG, Fu A, Geisler-Lee J, Hendrickson L, Geisler M, Stewart G, Krol M, Hurry V, Rodermel SR, Maxwell DP, Hüner NPA (2006) IMMUTANS does not act as a stress-induced safety valve in the protection of the photosynthetic apparatus of Arabidopsis during steady state photosynthesis. Plant Physiol, In press<br /> <br /> Salvucci ME, DeRidder BP, Portis AR Jr (2006) Effect of activase level and isoform on the thermotolerance of photosynthesis in Arabidopsis. J Ex. Bot, In press<br /> <br /> Sichler CM, Edwards GE, Kiirats O, Gao Z, Loescher W (2007) Response of mannitol-producing Arabidopsis thaliana to abiotic stress. Special Issue in Memory of Vincent R. Franceschi. Functional Plant Biol, Submitted<br /> <br /> Sioson AA, Mane SP, Sha W, Li P, Heath LS, Bohnert HJ, Grene R (2005) The TM4 microarray analysis software suite and the two-step ANOVA mixed model analysis method for the detection of significantly expressed genes; a comparison. BMC Bioinf 7: 215<br /> <br /> Spreitzer RJ, Peddi SR, Satagopan S (2005) Phylogenetic engineering at an interface between large and small subunits imparts land-plant kinetic properties to algal Rubisco. Proc Natl Acad Sci USA 102: 17225-17230<br /> <br /> <br /> Talamè V., Ozturk ZN, Bohnert HJ, Tuberosa R (2006) Dynamics of water loss affects the differential expression of drought-related genes in barley. J Exp Bot, In press<br /> <br /> Uribelarrea M, Moose SP, Below FE (2007). Divergent selection for grain protein affects nitrogen use in maize hybrids. Field Crops Res 100:82-90 <br /> <br /> Voznesenskaya EV, Franceschi VR, Chuong SDX, Edwards GE (2006) Functional characterization of phosphoenolpyruvate carboxykinase type C4 leaf anatomy: Immunocytochemical and ultrastructural analyses. Annals Bot 98: 77-91 <br /> <br /> Wang D, Portis AR Jr (2006) Increased sensitivity of oxidized large isoform of Rubisco activase to ADP inhibition is due to an interaction between its carboxyl-extension and nucleotide binding pocket. J Biol Chem 281: 25241-25249<br /> <br /> Wang D, Portis AR Jr (2006) Two conserved tryptophan residues are responsible for intrinsic fluorescence enhancement in Rubisco activase upon ATP binding. Photosyn Res 88: 185-193<br /> <br /> Watkinson JI, Hendricks L, Sioson AA, Vasquez-Robinet C, Stromberg V, Heath LS, Schuler M, Bohnert HJ, Bonierbale M, Grene R (2006) Accessions of Solanum tuberosum ssp. andigena show differences in physiological adaptation and acclimation to drought stress as reflected in gene expression profiles. Plant Sci 171: 745-758<br /> <br /> Xu W, Sato SJ, Clemente TE, Chollet R (2007) The PEP-carboxylase kinase gene family in Glycine max (GmPpcK1-4): An in-depth molecular analysis with nodulated, non-transgenic and transgenic plants. Plant J, In press<br /> <br /> Xu W, Ahmed S, Moriyama H, Chollet R (2006) The importance of the strictly conserved, C-terminal glycine residue in phosphoenolpyruvate carboxylase for overall catalysis. Mutagenesis and truncation of Gly-961 in the sorghum C4 leaf isoform. J Biol Chem 281: 17238-17245 <br /> <br /> Yep, A., Ballicora, M.A. and Preiss, Jack (2006) The ADP-glucose binding site of Escherichia coli Glycogen Synthase. Arch Biochem Biophys 453: 188-196<br /> <br /> Yu F, Park S, Rodermel SR (2005) Functional redundancy of AtFtsH metalloproteases in thylakoid membrane complexes. Plant Physiol 138: 1957-1966<br /> <br /> Zheng Z-L, Yang Z, Jang J-C, Metzger JD (2006) Phytochromes A1 and B1 have distinct functions in the photoperiodic control of flowering in the obligate long-day plant Nicotiana sylvestris. Plant Cell Environ 29: 1673-1685<br /> <br /> Zhu J-K, Bressan RA, Hasegawa PM, Pardo JM, Bohnert HJ (2005) Salt and crops: salinity tolerance. In: Success Story in Agriculture, Autumn/Winter 2005 issue of NewsCAST, USDA <br /> <br />

Impact Statements

1. Future increases in productivity, essential to support US agriculture and global demands for food and fiber, will be dependent on fundamentally new approaches to increase the capacity of crop plants to produce the nutrients that support growth of harvested plant parts, such as tubers and seeds. Basic research results reported in this years project update illustrate these approaches and directly contribute to the required knowledge base to effect these changes.
2. Fundamental studies of the biochemical mechanisms that control critical plant processes will directly contribute to the design of strategies to manipulate the photosynthetic capacity and quality of crop plants. The current report indicates that FtsH metalloproteases, such as VAR2, play an important role early in the process of plastid membrane biogenesis, a likely key component for modulating photosynthetic output.
3. The genetic engineering of Rubisco to increase net photosynthesis is proving to be difficult and various alternative strategies need to be explored. The reported results using chloropolast transformation have opened a new avenue for the evaluation and modification of foreign Rubisco genes in planta.
4. In order to increase crop yield potential and quality, it is essential to have fundamental knowledge of the underlying metabolic components that control assimilate production and utilization, and hence plant growth and development. Evidence that up-regulated forms of AGPase can increase starch biosynthesis in Arabidopsis and rice indicates there is potential to increase the capacity to utilize products of photosynthesis and thus increase plant growth.
5. Projected climate changes represent a significant threat to future crop and range production. Current results from field level manipulation of CO2, ozone, and precipitation will provide a basis for development of better mechanistic models to predict crop responses to global climate change. Ongoing experiments to characterize critical regulatory gene networks that control plant stress responses will provide targets for future genetic engineering.

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Report Information

Participants

Fred Below (University of Illinois), Christoph Benning (Michigan State University), Hans Bohnert (University of Illinois), Raymond Chollet* (University of Nebraska), John Cushman (University of Nevada), Gerald Edwards (Washington State University), Glenda E. Gillaspy (Virginia Tech), Irwin Goldman (University of Wisconsin, Administrative Advisor), Mark Guiltinan (Pennsylvania State University), Jeff Harper (University of Nevada), Robert Houtz (University of Kentucky), Steve Huber (USDA-ARS, University of Illinois), Jyan-Chyun Jang (Ohio State University), Robert Jones (University of Minnesota), Karen Koch (University of Florida), Wayne Loescher (Michigan State University), Stephen Long (University of Illinois), John Markwell* (University of Nebraska), Gail McLean (USDA, CSREES Representative), Ron Mittler (University of Nevada), Brandon Moore (Clemson University), Thomas Okita (Washington State University), Archie Portis* (USDA-ARS, University of Illinois), Jack Preiss (Michigan State University), Steven Rodermel (Iowa State University), Mary E. Rumpho (University of Maine), Michael E. Salvucci (USDA-ARS, Maricopa, AZ), Martin Spalding (Iowa State University), Robert Spreitzer (University of Nebraska), Donald P. Weeks (University of Nebraska) [*retired, last meeting]

Brief Summary of Minutes

This was the first meeting of Multistate Research Project NC1168 (Regulation of Photosynthetic Processes), which is the approved renewal of NC1142. The meeting was hosted by the Nebraska AES and held at the Beadle Center of the University of NebraskaLincoln on November 17, 2007.

Attending members included Christoph Benning, Raymond Chollet, Gerald Edwards, Glenda Gillaspy, Irwin Goldman, Karen Koch, Wayne Loescher, John Markwell, Gail McLean, Archie Portis, Jack Preiss, Mary Rumpho, Michael E. Salvucci, Robert J. Spreitzer, Donald P. Weeks, and Marna Yandeau-Nelson (for Guiltinan). Attending guests included Gary Cunningham (Dean and Director of the Nebraska AES) and Julie Stone (University of Nebraska).

The meeting convened at 8:50 AM in room E228 in the Beadle Center. Bob Spreitzer (Nebraska, AES) provided opening remarks and introduced Dr. Gary Cunningham, Dean and Director, Nebraska AES.


Bob Spreitzer then gave the first presentation on Rubisco engineering studies. A new member, Mary Rumpho, Maine AES, then presented her work on a sea slug that engulfs and maintains chloroplasts. Bob Spreitzer then introduced Irwin Goldman, NC1168 project administrator, who drove in from Madison, WI. Archie Portis, Illinois ARS, presented his work on genetic engineering of Rubisco in plants and member Hans Bohnerts work on a new algorithm to correlate gene expression patterns with gene function. At 10:35 AM a break occurred, and, at 10:55, Mike Salvucci, Arizona ARS, spoke about next years meeting in Arizona, an upcoming Gordon Conference on photosynthesis, and his work on Rubisco activase and heat stress. Don Weeks, Nebraska AES, spoke about carbon-concentrating mechanisms, a collaboration with member Martin Spalding. Lunch occurred in the atrium of the Beadle Center at 11:35 (hosted by the director of the Nebraska AES). The meeting reconvened at 1:00.

Gerry Edwards, Washington AES, described his work and also member Tom Okitas work on the AGPase enzyme. Karen Koch, Florida AES, spoke about sorbitol and carbon partitioning, followed by Marna Yandeau-Nelson, who spoke for member Mark Guiltinan, Pennsylvania AES, on the starch branching enzymes. After a break, Jack Preiss, Michigan AES, described his structural work, and added that this is perhaps his last meeting. Wayne Loescher, Michigan AES, spoke about sugar alcohols and plant stress. After a break, Glenda Gillaspy, Virginia AES, followed with a talk on sugar-alcohol synthesis genes. Christoph Benning, Michigan AES, spoke about plans to produce oils in canola that can be used for biodiesel production.

After a break, Irwin Goldman, Administrative Advisor, Wisconsin AES, provided an update on the last project (NC-1142), relaying that Bob Spreitzer was key in getting the new project (NC-1168) approved. Irwin then outlined the process of NCRA and encouraged members to let their Experiment Station directors know about NC1168 activities and the importance of this project. Irwin described how he could help organize an NC1168 meeting in the future and could provide assistance to the members of NC-1168. Irwin also announced that a progress report for NC1142 would be due soon, and that he would send inquires out by email at the beginning of the year requesting information for this report. Gail McLean, USDA/CSREES Representative then presented an update on USDA/NRI programs relevant to members. She outlined the current funding level and outlook for several programs. She added that it is important for this group to file annual reports.

At 5:05 PM the business meeting convened. Bob Spreitzer brought up the next and future meeting dates as related to whether the group should stay with the second weekend in November or switch to the third. Mike Salvucci remarked that hotel rooms in Arizona would be cheaper earlier in the season. After a discussion, the group decided to retain the second weekend in November as the meeting time for future meetings. Bob Spreitzer then remarked on the status of attending and non-attending members, adding that all members are active in attending the meetings. Jack Preiss inquired about Doug Randall, and Bob Spreitzer replied that Randall had retired. Bob Spreitzer announced a need for a new secretary, who would host the meeting in 2011, and who would be in charge of the project renewal. Christoph Benning was nominated and then elected to serve in this position. The renewal will be due in the Spring of 2012.

The schedule for future meetings was determined:

2008 Arizona AES Mike Salvucci
2009 Ohio AES J. C. Jang
2010 Virginia AES Glenda Gillaspy
2011 Michigan AES Christoph Benning

The meeting was adjourned at 5:20 PM.

Accomplishments

A. Plastid Function and Intracellular Communication. <br /> <br /> IA-AES has continued to investigate the role of the var2 gene of Arabidopsis (which encodes a chloroplast AtFtsH metalloprotease) in the repair of photodamaged photosystem II. Selection of suppressors has now identified genes encoding a polyribonucleotide phosphorylase and a chaperonin 60a that may also contribute to the assembly and regulation of the photosynthetic apparatus.<br /> <br /> ME-AES has continued to study the endosymbiotic relationship between the marine mollusk Elysia chlorotica (sea slug) and chloroplasts of the heterokont alga Vaucheria litorea. Sequences for phosphoribulokinase and the photosystem II Mn-stabilizing protein have been found in sea slug DNA, indicating that horizontal gene transfer may have occurred as a means for maintaining photosynthesis in the endosymbiotic algal chloroplasts.<br /> <br /> B. Photosynthetic Capture and Photorespiratory Release of CO2. <br /> <br /> IA-AES has identified a gene (lciB) responsible for the CO2-concentrating mechanism in the green algae Chlamydomonas reinhardtii. Further analysis, in collaboration with NE-AES, will evaluate the potential for transferring all or part of the CO2-concentrating mechanism into crop plants. NE-AES is using RNAi to study a possible bicarbonate transporter that may be involved in the CO2-concentrating mechanism.<br /> <br /> WA-AES is studying unique species in the family Chenopodiaceae that perform C4 photosynthesis without Kranz anatomy. Microtubules are critical for the maintenance of two cytoplasmic compartments. One type of chloroplast has Rubisco, starch biosynthesis, and well-developed grana, while the other type of chloroplast is specialized for supporting CO2 fixation in the C4 cycle. <br /> <br /> AZ-ARS and IL-ARS have continued to collaborate on Rubisco activase. An S-tagged b-isoform of activase has been engineered in Arabidopsis and crossed with an Arabidopsis plant expressing only the a-isoform. The new line will be used to examine the effects of temperature on interactions among activase subunits, and the effect of these interactions on Rubisco regulation. IL-ARS has transformed more-thermostable Rubisco activase into Arabidopsis to demonstrate improved photosynthesis and growth at elevated temperature.<br /> <br /> IL-ARS is attempting to eliminate rbcS gene expression in tobacco by employing RNAi technology. The Amaranthus rbcS gene has been introduced as a first step to see whether C4 Rubisco may provide a benefit for CO2 fixation. NE-AES has produced hybrid Rubisco enzymes in Chlamydomonas comprised of crop-plant small subunits and Chlamydomonas large subunits. Small subunits influence large-subunit catalysis. Phylogenetic analysis and directed mutagenesis have shown that large-subunit regions far from the active site can also influence catalysis.<br /> <br /> KY-AES has determined the polypeptide substrate specificity determinants for pea Rubisco large subunit methyltransferase using a fusion protein construct between the first 23 amino acids of the large subunit of Rubisco and human carbonic anhydrase II. RNAi-mediated knockdown of the methyltransferase in transgenic tobacco resulted in a two-fold decrease of a-tocopherol, the product of g-tocopherol methyltransferase, indicating that its consensus sequence may also be methylated. The crystal structure of Arabidopsis peptide deformylase 2 has been determined, and its substrate specificity is being defined.<br /> <br /> C. Mechanisms Regulating Photosynthate Partitioning. <br /> <br /> FL-AES has investigated a role for sorbitol metabolism and/or shuttling within developing kernels, possibly involving dual contributions to carbon transport and modulation of reducing power. Analysis of maize mutants has shown that sorbitol metabolism can contribute prominently to kernel capacity for sucrose import and use. FL-AES has also developed a method for 3'-UTR profiling that resolves expression to the level of individual gene family members and facilitates gene discovery. <br /> <br /> By whole-genome analysis, IL-AES has discovered that genes involved in nitrogen sensing and signaling may limit productivity in crop plants grown under elevated CO2 conditions. NV-AES has been identifying targets in nitrogen and carbon metabolism that interact with affinity-tagged 14-3-3 regulatory proteins in Arabidopsis. <br /> <br /> OH-AES is studying bZIP transcription factors involved in sugar signaling. SC-AES has shown that F-actin mediates some aspects of glucose signaling in Arabidopsis by interacting with mitochondrial hexokinase 1. Directed mutagenesis indicates that the hexokinase-like proteins, which lack glucose phosphorylation activity, may have specialized roles as regulatory components for glucose signaling. VA-AES is studying the synthesis and signaling functions of the sugar alcohol myo-inositol, which is linked to osmoprotective functions, signal transduction, and ascorbic acid synthesis, among other functions. Arabidopsis mutants lacking various members of the myo-inositol phosphate synthase and inositol monophosphatase enzyme families indicate that there are different subcellular locations for the first and second steps in myo-inositol synthesis.<br /> <br /> MI-AES is investigating the function and molecular biology of WRINKLED 1 and the genes controlled by this transcription factor in Arabidopsis. Analysis of mutants and engineered genes are clarifying the role of WRINKLED 1, pyruvate kinase, and glucose-6-phosphate dehydrogenase in the partitioning of photosynthetic carbon to oils. Understanding the conversion of photosynthetic sugars into triacylglycerols will be essential for the engineering of novel biofuel crops.<br /> <br /> MI-AES and WA-AES continue to define the structure-function relationships of ADP-glucose pyrophosphorylase, which catalyzes the first step in starch synthesis. Families of genes encoding the subunits have been analyzed in Arabidopsis. Hybrid enzymes and directed mutagenesis are being used to define regions involved in catalysis and regulation. This information will be used for the further engineering of improvements in the production of starch. WA-AES has used up-regulated forms of ADP-glucose pyrophosphorylase to increase leaf starch and biomass of Arabidopsis and rice. PA-AES is studying the starch branching enzymes of maize, which are critical in determining the molecular fine-structure of starch. Recent data indicate that starch branching enzyme activity in leaf extracts can be modulated by redox reactions. <br /> <br /> D. Developmental and Environmental Limitations to Photosynthesis. <br /> <br /> AZ-ARS and IL-ARS have shown that inhibition of photosynthesis and loss of Rubisco activation under moderate heat stress is more acute when Rubisco activase levels are suboptimal for photosynthesis, regardless of the isoform of activase. This finding is consistent with a proposed mechanism for inhibition of photosynthesis by heat stress based on the acute sensitivity of activase to thermal denaturation. New data indicate that chaperonin-60b plays a role in acclimating photosynthesis to heat stress, possibly by protecting Rubisco activase from thermal denaturation.<br /> <br /> IL-AES has found that chemical treatments promoting leaf greening in maize can disrupt ear development by altering ethylene sensing.<br /> <br /> IL-AES continues to exploit soyFACE (http://www.soyface.uiuc.edu) for investigating the effects of elevated CO2 on plant productivity. Metabolic profiling and gene-mining methods are being developed to analyze environmental stress effects. Gene networks are being defined.<br /> <br /> MI-AES and WA-AES have shown that expression of the mannitol biosynthetic enzyme gene, M6PR, in Arabidopsis improves salt tolerance. MI-AES is also studying the constitutive expression of the abiotic stress responsive transcription-factor gene, CBF3, and the plasma-membrane sodium antiporter gene, SOS1, in transgenic Arabidopsis to see whether further improvements in salt tolerance can be achieved.<br /> <br /> VA-AES is studying the role of myo-inositol signaling in abiotic stress. Protein-protein interactions in sugar signaling pathways are being identified.<br /> <br /> NV-AES has used microarray transcript profiling, quantitative RT-PCR, and metabolite profiling to show that metabolite differences found under long-term salinity or water deficit stress are linked to differences in transcript abundance of many genes involved in energy metabolism and nitrogen assimilation, particularly photosynthesis, gluconeogenesis, and photorespiration. Water-deficit-treated plants also appeared to have a higher demand than salinized plants to adjust osmotically, detoxify free radicals, and cope with photoinhibition. NV-AES is also screening through Arabidopsis mutants to identify genes that affect a plant's ability to grow under extreme environments. These genes provide important leads towards a goal of engineering higher-yield crops. <br />

Publications

Impact Statements

1. Further study of a protease, polyribonucleotide phosphorylase, and chaperonin 60a that play a role in the repair of photodamaged photosystem II may lead to the design of strategies for manipulating the photosynthetic capacity and quality of crop plants.
2. A deeper understanding of the endosymbiotic association between sea slug and algal chloroplasts may enable the maintenance of isolated organelles in culture or foreign hosts for long periods of time, thereby enabling large-scale production of chloroplast secondary products and/or alternative forms of photosynthetic energy production.
3. Transfer of the algal CO2-concentrating mechanism or C4 photosynthesis to C3 crop plants may improve photosynthetic productivity.
4. The discovery of a possible interaction between Rubisco activase and chaperonin-60 provides a new avenue for research into photosynthetic acclimation to moderate heat stress.
5. Improved thermal resistance of photosynthesis has been achieved by engineering a more-thermostable Rubisco activase.
6. Regions far from the active site have been identified as potential targets for the improvement of Rubisco and photosynthetic productivity.
7. Posttranslational methylation may be involved in the regulation of several chloroplast-localized enzymes. Further study may increase our understanding of how carbon reactions in the chloroplast can be altered to enhance photosynthetic efficiency.
8. The sdh1 (sorbitol dehydrogenase 1) maize mutant offers us a means for testing newly-revealed, but little-known roles of sugar alcohols in grain development.
9. Hexokinase-like proteins are not merely compromised in catalytic activity, but have specialized non-catalytic functions important for sugar signaling.
10. An alternate pathway for the synthesis of ascorbic acid from myo-inositol has been discovered. Because ascorbic acid is both an essential plant-derived nutrient for humans, and an important anti-oxidant in plants, understanding its synthesis can lead to new strategies for improving both human and plant health.
11. By developing schemes and new biofuel crops that lead to improved oil yield per acre of five-fold or more, biodiesel from plant oils could make up a significant fraction of renewable fuels.
12. ADP-glucose pyrophosphorylase has been shown to be a useful target for engineering increases in the production of starch and biomass.
13. New knowledge about the mechanisms of starch branch-point formation and its role in starch granule formation will lead to the development of novel starch types for industrial, medical, and food-processing applications.
14. Knowing when to apply chemical treatments to achieve leaf-greening without disrupting maize-ear development is clearly important to the agrochemical industry.
15. Peptide deformylase provides a unique opportunity for exploring potential alternatives to antibiotic-resistance markers in plant transformation vectors as well as alternative broad-spectrum herbicides.
16. In soyFACE elevated-CO2 experiments, superior ecotypes have been identified that are less affected by changes in environmental stress parameters.
17. Genetic engineering of improved salt tolerance has been achieved in Arabidopsis without a decline in photosynthesis.
18. Calcium signaling pathways are being defined that are responsible for plant survival under extreme environmental conditions such as cold, heat, drought, salt, and high-light stress.

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