Brief Summary of Minutes of Annual Meeting

Our W3168 Project that ended in 2019 had the following Objectives:

1. Identifying key factors involved in the enhancement or loss of seed quality.
2. Eliminating seed dormancy as a constraint during seed production and germination in agronomic seed production and ecological/biomass seed establishment.
3. Enhancing seed vigor and germination in agronomic and other species for improved stand establishment.

Our W4168 Project that started in 2019 has the following Objectives:

1. Understand how developmental and environmental mechanisms affect seed quality.
2. Capitalize on new technologies to assess and manipulate traits to enhance seed quality.

Research Objectives for each station and group shown below (W3168/W4168):

AZ, Ramin Yadegari (1/1)

FL, Hector Perez (1, 3/1, 2)

IA, Susana Goggi (Iowa State U.)

KY, Bruce Downie (1, 3/1)

KY, Robert Geneve (2, 3/2)

NY, Alan Taylor (3/2)

OR, Sabry Elias (1/1)

SD, Xingyou Gu (1, 2/1)

TX, Daniel Leskovar (3/2)

VA, Gregory Welbaum (3/2)

AZ (Yadegari)

Research was focused on analysis of the regulatory mechanisms that control accumulation of storage proteins and starch during mid to late stages of endosperm development in maize (Zea mays). Development of the cereal endosperm involves cell differentiation processes that enable nutrient uptake from the maternal plant, accumulation of storage products and their utilization during germination. We have used the Opaque-2 (O2) bZIP transcription-factor protein and its downstream network involved in regulation of storage protein gene expression in maize. During this period of our studies, we focused on dissecting the temporal sequence of gene activation and repression events in both wild-type and o2 mutant endosperm in maize inbred line B73 using RNA-Seq. Our data indicates multiple transitions in gene expression programs, some coinciding with previously known developmental transitions and some that may identify novel switches in temporal development of maize endosperm. We plan to further characterize the nature of gene functions associated with these gene sets.

FL (Perez)

We identified environmental parameters that clarify the germination niche for seeds of a federally listed endangered plant (Linum arenicola) in collaboration with partners from Fairchild Tropical Botanic Garden. We also uncovered differential viability and vigor loss patterns of mass separated Rudbeckia mollis seeds in response to storage conditions (e.g. climate-controlled vs. non-climate-controlled systems) and aging stress imposed by the combination of high temperature and relative humidity. Subsequently, we discovered similar seasonal dormancy cycling across all R. mollis seed mass fractions. Rudebckia mollis seeds of greater mass may also possess a competitive advantage over seeds of smaller mass in defending against pathogen attack during burial in the soil profile. We related this advantage to relatively thicker seed coats in seeds of larger mass. However, the seed coat pathogen defense system seems to reflect a trade-off with defense against aging stress such that more rapid viability loss due to physiological mechanisms is evident in larger compared to smaller seeds. We partnered with a local wildflower seed producer to obtain seeds of Rudbeckia mollis and plan to share research results with the Florida Wildflower Foundation. Outputs and Short-term Outcomes: Data from our research on Linum arenciola was incorporated into the Conservation Action Plan for this species. Conservation Action Plans outline management activities for the recovery of endangered species. Our observations regarding Rudbeckia mollis highlight the importance of distinguishing between pre-sowing storage and post-storage vigour effects when quantifying relative levels of viability loss among seeds of different mass. Additionally, this work can shed more light on seed persistence dynamics in the soil. The work on R. mollis has implications for understanding potential shifts in population demographics and dynamics for seeds in general. Likewise, information generated from our work on Uniola paniculata is useful to manage germplasm and enhance seed production methods for this economically and ecologically important dune building species. We presented our research at one international and one regional meeting. Activities: We carried out lab-based research including: germination chamber screenings at various seasonal temperatures and lighting regimes, thermo-gradient table experiments, accelerated aging experiments, microscopy (i.e. optical and electron), stress-based dose response experiments, respirometry, and multi-spectral scanning. Field research consisted of implementing burial-retrieval-germination studies and in situ germination phenology experiments. Milestones: We plan to submit: 1) 1-2 articles related to L. arenicola research by 30-Mar-2020; 2) 2 articles on R. mollis work by 06-Dec-2019 and 30-Mar-2020; and 3) 1-2 manuscripts related to work on U. paniculata by 31-Aug-2020.

KY (Downie)

Short-term Outcomes: There are none. As strictly basic research there is no means by which anyone will be able to make a profit from this work, use it to start a business, or otherwise identify a tangible accumulation of wealth or food from it. Similarly it will not immediately help the environment. Those operating seed banks will understand that the proteins of the translational apparatus are the most important of the proteome to protect from damage if the seed is to remain viable. However, understanding this is the case will not assist them in preserving these proteins from damage any more than is inherent in the seed’s current protection and repair mechanism. Outputs: The primary output from these endeavors are the ideas that they generate and the demonstrations of how important aspect of the protective mechanism (Raffinose Family Oligosaccharides, LATE EMBRYOGENESIS ABUNDANT PROTEINs; LEAP) are to long term seed viability. Activities: Dr. Lynnette Dirk and Dr. Bruce Downie engaged in cloning LEAP coding sequences into bacterial vectors, expressing these and purifying the recombinant proteins. These were used by the team, including a high school student, to robotically assess LEAP binding to Arabidopsis seed proteins displayed on virus coat proteins, assembling the Client Proteins (CP) for each of the LEAPs we expressed of the 51 LEAPs present in Arabidopsis thaliana. Using an Illumina sequencing technique (Paired-End Phage Sequencing; PEPSeq) tags were generated from the phage sub-libraries that constituted the  LEAP:CP repertoire. An affiliated team of bioinformaticians in Brazil are using this information to develop the Paired End Phage Explorer pipeline (PEPE). This will finally unveil the CPs associated with a specific Arabidopsis LEAP and its Soybean (Glycine max) orthologous LEAP. Other endeavors include using HPLC to explore maize (Zea mays), rice (Oryza sativa), and Arabidopsis mutants and over-expressing lines compromised in or ectopically expressing various enzymes and transcription factors influencing soluble saccharide quantities and qualities in the various seeds of the plants mentioned above. These efforts will continue in the next year of this project. Milestones: Complete the final biological replication of feeding various saccharide solutions to developing maize kernels using intravenous lines. Assess the resulting kernels for disrupted sugar quantities and qualities using HPLC. Develop the transgenic, over-expressing, Arabidopsis lines of the various LEAPs for which we have detailed CP information from Phage display and assess them, along with their insertional mutants for phenotypes relative to wild type seeds/plants. Continue to consult with the Brazilian team on improvements to and working out bugs in PEPE.

KY (Geneve)

Intended activities: The research focused on determining the basic germination parameters for industrial hemp (Cannabis sativa). This included information related to temperature and the development of a seed priming protocol. Outcomes: Cardinal temperatures for industrial hemp were determined for several accessions utilizing a thermogradient table. A thermal time model was developed that determined that optimal germination occurred between 17 and 25^oC. Protocols for osmotic- and solid matrix-seed priming were developed utilizing three seed accessions. Seed priming improved germination and stand establishment under greenhouse and field conditions. Outputs: Results from these studies were communicated to hemp growers at the University of Kentucky 2019 Hemp Field Day. This field day had over 500 grower participants. A formal presentation was made to seedling transplant producers at the 2019 International Plant Propagator’s Society – Eastern region annual meeting in Madison, Wisconsin regarding “Opportunities in Commercial Hemp Production”. A journal manuscript “Temperature Limits for Seed Germination in Industrial Hemp (Cannabis sativa L.)” was submitted to Seed Science Research.

NY (Taylor)

A novel delivery method for the application of bio-based biostimulants as seed coatings was developed using different sources of liquid and powder forms of vermicompost and soy flour. Micronized vermicompost (MVC) and soy flour (SF) were mixed in different combinations as dry seed coating blends and applied using rotary pan seed coating equipment. The physical properties of coated seeds were measured, and as binder concentration increased, coating strength increased. The rates and percentages of germination of these coating formulations of SF+MVC did not decrease the germination parameters and were not significantly different than the control. However, the SF, SF with concentrated vermicompost extract, and SF + MVC from dairy manure increased the seedling vigor index by 24, 30, and 39 percent, respectively, compared to the control. Plant biometric parameters and nitrogen uptake per plant were also significantly higher for SF and SF+MVC coated seeds than the control, in a greenhouse environment. This is the first seed coating study to show an enhancement of plant growth with vermicompost, and vermicompost in combination with a plant-based protein that serves as a dry seed coating binder and biostimulant, respectively. Seed coatings developed in this study can serve as a model for development of the delivery systems of seeds for the application of bio-based biostimulants to enhance early plant growth.

OR (Elias)

The objectives of this study were to: 1) examine the extent of dormancy in freshly harvested seeds and develop a method to break it, 2) measure the effect of having seeds with different ages in the same plant on the quality of harvested seeds, and 3) determine the suitable tests to measure seed viability and vigor. Two varieties with different seed sizes were included in the study. The quality of seeds harvested from the upper 2/3 part of the plant (mature seeds) and from the lower 1/3 part (under developed seeds) were compared. The length of dormancy in freshly harvested seeds was measured. Both varieties had a short-lived dormancy (30-45 days). Pre-chilling treatment (10°C for 5d) was effective in breaking dormancy. The difference in seed size between the two varieties did not impact seed quality. Seeds harvested from the upper part of the plant had higher quality than those from the lower part of the plant.  Seeds from the lower part of the plant need to stay an extra 7-8 days on the mother plant to reach similar quality to the upper part.  Tetrazolium, standard germination, and accelerated aging tests were suitable for measuring seed quality. These findings can increase hemp yield by 1/3 if harvest is delayed 7d. The current practice in most production systems is to harvest only the upper 2/3 of the plants.

SD (Gu)

Our research was focused on seed dormancy and soil seedbank longevity. A new project was funded by USDA-NIFA Foundational Program to identify interactional partners, target genes, and the pre-harvest sprouting resistance of SD12s, a multi-genic quantitative trait locus (QTL) for seed dormancy in rice. A series of molecular biology experimental systems were developed, and candidate partners or downstream genes were screened for further confirmation. Hybridization between SD12’s isogenic lines (donors) and male sterility maintaining or restoration lines (recipients) were made to introduce the dormancy gene(s) into the recipient background by marker-assisted backcrossing. The other project was newly funded by USDA-NIFA BRAG Program to evaluate effects of seed dormancy genes on soil seedbank longevity (SL) and to identify new SL QTL and their G×E interactions in till and no-till cropping systems. Four seed dormancy genes, including their combinations, were all involved in regulation of SL in the soil; and the data were published. A population of 450 recombinant inbred lines (RILs) in the F12 generation were purified and propagated; seed samples are being used to evaluate for SL in the soil of a rice field. In addition, a new project was initiated to elucidate epigenetic mechanisms of seed dormancy using a model system developed from weedy rice. Five graduate students and three postdoc/visiting scientists were received training in the above-stated projects.

TX (Leskovar)

Intended activities: The research for this year focused on two projects: 1. Determine how selective organic media containing humic substances impact transplant quality traits and reduce transplant sock of high value vegetable species growing under drought and heat stress conditions, and 2. Determine best grafted tomato combinations (scion/rootstock) based on yield and quality stability across diverse environments in Texas.  Outcomes: Using lignite-based humic substances (HS) applied to a peat-growth medium, the study evaluated seedling growth responses of four vegetable species each with two different cultivars: pepper (bell- and jalapeno-type), tomato (round- and cherry-type), watermelon (seeded 2x, and seedless 3x), and lettuce (Romaine- and Bibb-type).  Once seedlings traits were measured in the nursery, transplants from each crop/cultivar were field transplanted under drought (vs. well-watered) and heat (vs. cool temperatures) conditions. Overall, HS-treated transplants had: 1) increased leaf and root biomass after transplanting due to faster growth rate compared to control; 2) lower root/shoot ratio before transplanting, but higher after 10 days; 3) increased root length and surface area. Yield increases due to HS depended on crop and environmental conditions: bell-pepper under drought and heat stresses; round- and cherry-tomato under well-watered and cool season (no stress); triploid-watermelon under well-watered and hot season; romaine-lettuce under heat stress. In the tomato grafting project, the team identified grafted tomato combinations (scion/rootstock) with high stability for yields and yield components across diverse environments in Texas. Grafted plants consistently increased marketable yields by 5 to 69%. Outputs: Results from these two studies were communicated to growers at the Uvalde May 2019 Vegetable Field Day, which was attended by +80 participants. Participants also took a hands-on tomato grafting workshop class, which was complemented with an educational seminar highlighting the science behind grafting. The event was covered by AgriLife Today and other regional outlets https://agrilifetoday.tamu.edu/2019/05/14/vegetable-wheat-field-day-at-texas-am-agrilife-center-in-uvalde-draws-producerinterest/  Findings were also presented and discussed in seven oral presentations at the: annual meetings of the American Society of Horticultural Sciences (Las Vegas, NV); Grafting Symposium, International Society of Horticultural Sciences (Charlotte, NC); vegetable field days; and annual ASA-Agronomy Society graduate student field day (San Antonio, TX). Two manuscripts were published from previous work, one chapter book on ‘Transplanting’ is in press in the 2^nd edition of the Vegetable Physiology book, two were submitted to Acta Horticulturae, and three related to 2019   projects are about to be submitted to peer reviewed Journals.

VA (Welbaum)

We now know that tobacco mosaic virus can be transmitted to the next generation of plants by both by seed coat transmission and embryo transmission. Using plastic tunnels for vegetable production can increase the water use efficiency of certain crops. Wild tobacco plants can be infected with the cucurbit disease, bacterial fruit blotch, enabling easier study of the pathogen/plant genetic interactions that are responsible for infection. During the past year, four masters-degree students and one Ph.D. student have been trained and received degrees from this research. 

Campbell-Martinez, G., M. Thetford, D. Miller and H.E. Pérez. 2019. Seedling emergence of Lupinus diffusus in response to abrasion in an electric seed scarifier. Native Plants Journal. 20:14-24.

Han Q., Qi J., Hao G., Zhang C., Wang C., Dirk L.M.A., Downie A.B., Zhao T. 2019. ZmDREB1A regulates RAFFINOSE SYNTHASE controlling raffinose accumulation and vegetative chilling stress tolerance in maize. Plant and Cell Physiology. doi:10.1093/pcp/pcz200

AL-Amery M., Downie B., DeBolt S., Crocker M., Urschel K., Goff B., Teets N., Gollihue J., Hildebrand D. 2019. Proximate composition of enhanced DGAT high oil, high protein soybeans. Biocatalysis and Agricultural Biotechnology. 21: 101303.

Gu L, Jiang T, Zhang C, Li X, Wang C, Zhang Y, Li T, Dirk L, Downie B, Zhao T. 2019. Maize HSFA2 and HSBP2 interact with each other and antagonistically modulate raffinose biosynthesis and plant abiotic stress tolerance. The Plant Journal. TPJ-00441-2019. doi: 10.1111/tpj.14434

Zhang Y, Sun Q, Zhang C, Hao G, Wang C, Dirk LMA, Downie AB, Zhao TY. 2019. Maize VIVIPAROUS1 interacts with ABA INSENSITIVE5 to regulate GALACTINOL SYNTHASE2 expression controlling seed raffinose accumulation. Journal of Agricultural and Food Chemistry. 67: 4214-4223.

Lynnette M. A. Dirk, and A. Bruce Downie. 2018. An examination of Job’s rule: Protection and repair of the proteins of the translational apparatus in seeds. Seed Science Research. 28, 168–181. https://doi.org/10.1017/S0960258518000284.

Lynnette M.A. Dirk, Manoj Majee, Santosh Kumar, A. Bruce Downie. 2018. PHYTOCHROME INTERACTING FACTOR1 interactions leading to the completion or prolongation of seed germination. Plant Signaling and Behavior. 13(10):e1525999 DOI: 10.1080/15592324.2018.1525999.

Manoj Majee, Santosh Kumar, Praveen Kumar Kathare, Shuiqin Wu, Derek Gingerich, Nihar R Nayak, Louai Salaita, Randy Dinkins, Kathleen Martin, Michael Goodin, Lynnette M.A. Dirk, Taylor D. Lloyd, Ling Zhu, Joseph Chappell, Art G. Hunt, Richard Vierstra, Enamul Huq, and A. Bruce Downie. 2018. KELCH F-BOX Protein Positively Influences Seed Germination by Targeting PHYTOCHROME-INTERACTING FACTOR1. Proceedings of the National Academy of Science U.S.A. 115 (17) E4120-E4129.

Wilson, S.B., R.L. Geneve and F.T. Davies, Jr. 2018. An online study tool for reviewing plant propagation terms and concepts. HortTechnology 28:851-854.

https://doi.org/10.21273/HORTTECH04184-18  

AL-Amery, M., Geneve, R.L., M.F. Sanches, P.R. Armstrong, E.B. Maghirang, C. Lee, R.D. Vieira, and D.F. Hildebrand. 2018. Near-infrared spectroscopy used to predict seed germination and vigour in soybean seed lots. Seed Science Research 1–8  

https://doi.org/10.1017/S0960258518000119

Geneve, R.L. and S.T. Kester. 2018. Morphophysiological dormancy in Heptacodium. Seed Science Research 1-5 https://doi.org/10.1017/S0960258518000053

Geneve, R.L., C.C. Baskin, J.M. Baskin, K.M.G. Jayasuriya, and N.S. Gama-Arachchige. 2018. Functional morpho-anatomy of water gap complexes in physically dormant seed. Seed Science Research 1-6 https://doi.org/10.1017/S0960258518000089

Davies, F. T. Jr., R. L. Geneve and S. B. Wilson. 2018.  Hartmann and Kester’s Plant Propagation:  Principles and Practices.  Boston: Prentice-Hall.  Ninth edition.

Amirkhani, M., Mayton, H.S., Netravali, A.N. and Taylor, A.G. 2019. A Seed Coating Delivery System for Bio-Based Biostimulants to Enhance Plant Growth. Sustainability  11, 5304. https://doi.org/10.3390/su11195304

Huang, W. and A.G. Taylor. 2019. Water uptake, respiration and germination of eastern gamagrass seeds as influences by mechanical seed treatments: Unlocking mechanisms of seed dormancy. Seed Science and Technology, 47, 2, 1-15. https://doi.org/10.15258/sst.2019.47.2.06

Pipatpongpinyo, W., U. Korkmaz, H. Wu, A. Kena, H. Ye, J. Feng, and X.-Y. Gu. 2019. Assembling seed dormancy genes into a system identified their effects on seedbank longevity in weedy rice. Heredity. (doi.org/10.1038/s41437-019-0253-8).

Macias-Leon, M. A. and D.I. Leskovar. 2019. Containerized onion transplant: Management systems to enhance growth, yield and quality. HortScience 54:60-69.  https://doi.org/10.21273/HORTSCI13438-18

Othman, Y.A. and D. I. Leskovar. 2019. Nitrogen management influenced root length intensity of young olive trees. Scientia Horticulturae 246, 726-733. https://doi.org/10.1016/j.scienta.2018.11.052

Leskovar, D.I. and Othman. 2019. Nitrogen management for improving root and shoot components of young 'Arbequina' olives.  HortScience 54:175-180. https://doi.org/10.21273/HORTSCI13397-18

Agehara, S. and D.I. Leskovar. 2018. Optimizing spray application rates of abscisic acid for height control of jalapeño transplants. Acta Hortic. 1204, 235-242 DOI: 10.17660/ActaHortic.2018.1204.31
https://doi.org/10.17660/ActaHortic.2018.1204.31

Leskovar, D.I. and Othman, Y. 2018. Efficacy of 1-methylcyclopropene in promoting shoot growth of tomato transplants. Acta Hortic. 1204, 229-234 DOI: 10.17660/ActaHortic.2018.1204.30
https://doi.org/10.17660/ActaHortic.2018.1204.30

Ellis, Madeleine D., Jessica M. Hoak, Bradley W. Ellis, Jessica A. Brown, Tim L. Sit, Carol A. Wilkinson, T. David Reed, and Gregory Welbaum. 2019 "Quantitative real-time PCR analysis of individual flue-cured tobacco seeds and seedlings reveals seed transmission of Tobacco mosaic virus." Phytopathology DOI: 10.1094/PHYTO-06-19-0201-FI.

Traore, S.M., Eckshtain?Levi, N., Miao, J., Castro Sparks, A., Wang, Z., Wang, K., Li, Q., Burdman, S., Walcott, R., Welbaum, G.E. and Zhao, B., 2019. Nicotiana species as surrogate host for studying the pathogenicity of Acidovorax citrulli, the causal agent of bacterial fruit blotch of cucurbits. Molecular Plant Pathology. 20: 800–814.

Acharya, T.P., Welbaum, G.E. and Arancibia, R.A., 2019. Low Tunnels Reduce Irrigation Water Needs and Increase Growth, Yield, and Water-use Efficiency in Brussels Sprouts Production. HortScience. 54: 470-475.