Brief Summary of Minutes of Annual Meeting

February 13, 2008 The 2007 WERA-066 meeting was held in conjunction with the International Plant Resistance to Insects conference (February 10-13) at the Hilton Ft. Collins (See attached agenda). Therefore, the annual meeting consisted of a brief business meeting that was scheduled from 1:00-4:00 pm, February 13, 2008. Chair Phil Sloderbeck, called the meeting to order at 1:00 pm and began the meeting with a round of introductions by those in attendance. Phil then introduced administrative co-advisor Tom Holtzer to address the group. Tom Holtzer, Colorado State University, Administrative Advisor, provided a charge for the group and encouraged all to enroll into the NIMSS system http://www.lgu.umd.edu/lgumanual/toc.html. This meeting worked well as a partner meeting with IPRI meeting. Accountability is important, shows accomplishments and impacts of research and educational programs. John Reese led discussion about developing collaborations with IPRI as Gary Thompson discussed. 1:15 PM  State Reports -- Verbal reports were given by representatives from each state (Name in Parentheses) summarizing their written reports of recent insect activity and research results: Colorado  (Frank Peairs): Discussed the importance of spiders in system. Need for RWA-1 and RWA-2 resistant differentials to evaluate RWA biotypes. Kansas  (John Reese) Evaluating resistance to RWA-2 in wheat and barley. Looking at soybean aphid resistance Nebraska- (Gary Hein) Barley, relationships to barley natural enemies. Areawide project in winter wheat completed. RWA research that is being conducted by Tiffany Heng-Moss is looking at gene expression profiling. Cereal arthropod research includes wheat curl mite, characterizing genetic diversity, virus transmission and mite movement potential. RWA populations were down from a year ago but other cereal aphids were present. BCO, English grain aphids, Greenbug. Barley Yellow Dwarf Virus were more prevalent than usual. North Dakota  (Kirk Anderson for Marion Harris) 2007 IPM Survey. 1000 wheat fields in 53 counties, for diseases and insects. Grasshopper populations were low, wheat stem maggot numbers are higher. Hessian fly: an independent survey showed that it is at an economic level in some fields. Orange wheat blossom midge survey: the trend is lower levels of wheat midge, but a few areas had treatable numbers. Oklahoma ARS (Do Mornhinweg) Released 7 winter barley resistant lines. Many spring barley resistant lines for RWA. Are developing (developed) a seedling screen for BCOA. (Cheryl Baker): Resistance lines for RWA1 and RWA1 are being identified. (Gary Purterka) Collaborative agreement with Dr. Dillwith, looking at salivary gland constituents. Oklahoma (Tom Royer) Hessian fly is prevalent, we are finding some wheat stem maggot in our plots, and dont know what impact that would have for this spring. We are validating the Glance n Go sampling system for greenbugs in Kansas, Oklahoma and Texas with growers (8 per state). South Dakota (Louis Hesler) BCOA fall with BYDV. High populations in spring, mostly English Grain Aphid, some BCOA and greenbug. Looking for HPR for BCOA, found some in triticale, but breeders are not interested in crossing. Following reports, discussion was initiated to determine the location and date of the next meeting. After a discussion with Dr. Holtzer about the time span needed for each meeting, the group agreed to explore the possibility of holding the meeting on September 22 or September 29, 2009 in Ardmore, OK, or Stillwater, OK. John Burd will make contacts with personnel at the Noble Research Center to see if they would host this meeting. The next item of business was to identify the next secretary for WERA-66. Christie Williams, Purdue University, was identified by the nominations committee as a willing candidate, so Do Mornhinweg moved that she be nominated, seconded by Frank Peairs, and passed unanimously. Meeting was adjourned at 4:00 pm.

(Selected brief statements from State Reports. Full State Reports are in the file attached under Summary of Minutes.) COLORADO Pitfall traps have been established at three cropping systems sites. Spiders are being collected and identified. A manuscript on carabid results is in press. Uniform aphid natural enemy observations are taken at all three locations Russian wheat aphid biotype 1-resistant wheat cultivars are now planted on more than 25% of Colorados wheat acreage. The level of use has remained constant even though RWA-1 seems to have been largely replaced by RWA-2. Winter wheat lines with the 2414-11 resistance source continue to be advanced. Two will be evaluated for yield loss to Biotype 2 in the spring of 2008. Resistant feed barley varieties were tested on-farm in 2006 and 2007. Stoneham and Sidney are resistant to known RWA biotypes and performed better than Otis, their recurrent parent, under very dry conditions and in the presence of Russian wheat aphid. Surveys were conducted to determine the presence of Dn4-virulent Russian wheat aphids. Russian wheat aphid was scarce in 2007, but the percentage of samples containing Dn-4 virulent aphids has continued to increase since the initial survey in 2004 (96% in 2007). No virulence to 2414-11 was detected. An additional 2300 lines from the national wheat germplasm collection, 600 other breeding lines and 4500 individual progeny were screened for resistance to Biotype 2. Additional potential resistance sources were identified for bothRWA-1 and RWA-2. Dryland cropping systems studies are ongoing at three locations in eastern Colorado. Stoneham, a RWA-resistant feed barley, has been added to some rotations. Generally, rotations have been modified to incorporate more forages, and sunflower has been eliminated. Aphid flights were monitored at four locations by means of suction traps. For the first time, zero Russian wheat aphids were collected in the Akron trap, and only one was collected from the Briggsdale trap. Nine foliar insecticide treatments were compared to commercial standard insecticide treatments for control of Russian wheat aphid in winter wheat. Cobalt (chlorpyrifos + gamma cyhalothrin) was similar in performance to the standard chlorpyrifos treatment, which currently is the product of choice for Colorado wheat producers. Methomyl was compared to chlorpyrifos and several pyrethroids for control of Russian wheat aphid in spring barley. Two applications of methomyl performed nearly as well as the chlorpyrifos treatment, providing barley producers with another potential control option. INDIANA Insect feeding disrupted by wheat lectin. Production of the HFR-1 wheat lectin is triggered by avirulent Hessian fly larvae. Because these larvae are obligate parasites and cannot be cultured in vitro, the effect of this lectin was tested on Drosophila melanogaster larvae as they consumed an artificial diet. At low to intermediate concentrations, this lectin prolonged larval development. But at high concentrations it deterred feeding and repelled the larvae, causing them to leave the diet medium and reside on the sides of the glass vial until death, 4 days later. This lectin may be useful as a feeding deterrent in transgenic plants. Amino acid content of susceptible plants is manipulated by virulent Hessian fly larvae. Virulent Hessian fly larvae alter the production of certain amino acids in their host wheat plants. Essential amino acids that the larvae must obtain from their diet increase in abundance in susceptible wheat. This includes methionine, histidine and phenylalanine. The increased production of phenylalanine and tyrosine by the host wheat plant may be important for cuticle production in the immature insects. Molecular interaction between Hessian fly and wheat Previous research directed toward transcriptional profiling of genes expressed in Hessian fly larvae during interactions with wheat has revealed the following: 1. On susceptible plants genes involved in establishing a sustained feeding site, manipulation of host-plant cells, feeding and growth/development are up-regulated; 2. On resistant plants genes involved in responding to stress and disruption of homeostasis (DAD  defender against apoptotic cell death, heat shock, detoxification, antioxidant defense, excretion, etc) are up-regulated; 3. On resistant plants larvae encounter toxic plant compounds, feeding deterrents, or cannot manipulate host-plant cells to develop a nutritive tissue. Current research is focused toward: 1. RNAi as a function genomics tool for genes expressed during Hessian fly/wheat interactions; 2. comparative salivary gland transcriptomics; 3. electron microscopy studies of the larval midgut during compatible and incompatible interactions with wheat. Progress toward understanding Hessian fly biotypes. A bacterial artificial chromosome (BAC) based physical genetic map has been constructed of the Hessian fly genome. This map consists of 270 BAC fingerprint derived contigs (FPC) positioned in the genome by fluorescence in situ hybridization (FISH). The ends of the BACs in these contigs have been end-sequenced and an additional 100 simple sequence repeat (SSR) markers have been identified on BACs in the map. The BACs and the contigs can be identified using Hessian fly Web FPC: http://genome.purdue.edu/WebAGCoL/Hfly/WebFPC/. Three genes that determine the biotype status of Hessian fly larvae have been positioned on the physical genetic map. These genes determine the ability of the larvae to survive and stunt wheat carrying the specific resistance genes H6, H9, and H13. Generally referred to as Avriulence (Avr) genes, they have been named according to their corresponding resistance gene as vH6, vH9, and vH13. vH6 has been positioned between two adjacent contigs on the long arm of Hessian fly chromosome X2. Three genetic map units separate the contigs. vH9 has been positioned within a single contig on the short arm of Hessian fly chromosome X1. vH13 has been positioned within a single BAC clone within a contig on the short arm of Hessian fly chromosome X2. Results clearly indicate that Hessian fly virulence and avirulence to specific resistance genes in wheat results from mutations in single genes. Thus, the wheat-Hessian fly interaction clearly appears to have a gene-for-gene basis. KANSAS Comparisons of Wheat and Barley Resistance to Russian Wheat Aphid Biotype 2. This research project reports the categories of resistance (antibiosis, antixenosis, tolerance) to Russian wheat aphid, Diuraphis noxia (Kurdjumov), biotype 2 present in a cereal introduction Triticeae (CItr) 2401, and a barley breeding line (IBRWAGP04-7), when compared to control resistant and susceptible wheat and barley genotypes. CItr2401 and IBRWAGP04-7 exhibit no antixenosis to D. noxia biotype 2, but both lines demonstrate antibiosis to D. noxia in the form of reduced aphid populations in comparison to susceptible controls. Leaf and root dry weight changes exhibited by infested CItr2401 and IBRWAGP04-7 plants were significantly less than those of infested plants of the susceptible control varieties. However, when a tolerance index was calculated to correct for differences in aphid populations, these differences in D. noxia tolerance to were negated. Categories of Resistance to the Russian Wheat Aphid Biotype 2 Operating in Parents of Aphid-Resistant CIMMYT Synthetic Wheat Lines. To identify and characterize sources of North American to D. noxia biotype 2 resistance, synthetic hexaploid wheat lines created at the International Maize and Wheat Improvement Center (CIMMYT) were evaluated for potential resistance. Several CIMMYT genotypes and their parents were resistant to aphid induced - leaf rolling and chlorosis, and sustained significantly less damage than plants of the susceptible control Jagger. In general, fewer biotype 2 aphids were produced on genotypes with reduced chlorosis and leaf rolling, and aphid numbers were highly correlated with chlorosis and with leaf rolling. However, large biotype 2 populations developed on the parent line Ae. tauschii 518, although this genotype was highly resistant to leaf rolling and chlorosis. These biotype 2 resistant lines, which are also resistant to D. noxia populations in Mexico and to greenbug, Schizaphis graminum Rondani, biotype G, are strong candidates for use in improving the genetic diversity in bread wheat for resistance to different biotypes of both S. graminum and D. noxia. Categories of Resistance to Russian Wheat Aphid Biotype 2 in Bread Wheat Genotypes. Diuraphis noxia North American biotype 2 is virulent to the D. noxia resistance genes Dn1, Dn2, Dn4, Dn5 and Dn6. Thus, a need exists for an improved understanding of the categories of resistance in all sources of biotype 2 resistance. In this study, wheat genotypes containing the resistance genes Dn4, Dn6, Dn7, Dnx, and a susceptible control (Dn0) were infested with D. noxia biotype 2 to determine the extent of the antibiosis and tolerance categories of resistance operating in each genotype. All infested resistant genotypes expressed some chlorosis and leaf rolling. Tolerance indices (TI) for shoots, roots and plant height of Dn6 were significantly lower (more tolerant) than those of Dn0. Plant height TI of Dnx plants was also significantly less than that of Dn0. Thus, both Dn6 and Dnx plants are tolerant to D. noxia biotype 2 infestation. Both Dn7 and Dnx plants exert antibiosis effects and significantly reduce D. noxia populations compared to Dn0. Despite the strong resistance of the Dn7 genotype from rye, Dn7 has deleterious effects on bread wheat baking quality. Dnx, from bread wheat, carries no negative quality traits and offers a suitable genotype for ready adaptation into Kansas wheat cultivars. Interactions Among Biological Control, Cultural Control and Barley Resistance to the Russian Wheat Aphid in Colorado, Kansas and Nebraska. This research is being conducted to determine the interaction among biological control, cultural control and barley resistance to the Russian wheat aphid resistance in fields located in Colorado, Kansas, and Nebraska. The experimental design is a split-plot design with two main plot treatments (early, and delayed planting dates). Within each main treatment plot, four split-plot treatments (varieties) are randomized. In 2007, these treatments included two new D. noxia biotype 1 and 2 resistant barley cultivars, Stoneham and Sydney, and the susceptible cultivar Otis under triamethoxam-protected and unprotected regimes. Aphid, natural enemy and incidence sampling was conducted at four dates from late May through early July in 2007. Differences in the mean number of aphids were detected by location and variety during the second sampling, when unprotected Otis plants contained the highest numbers of aphids in Colorado and Kansas. On the third sampling date, unprotected Otis plants in Nebraska contained the highest numbers of aphids. There were complex interactions between the natural enemies observed in the three fields and these are being subjected to further analyses. NEBRASKA Demonstration Trials of New Resistant Barely Varieties This project was done cooperatively with Frank Peairs (CSU) to test the new RWA resistant barley varieties (Sidney, Stoneham) in larger strip trials in various environments for yield and aphid response. Through the Nebraska panhandle and Colorado we had twelve trial sites out. The four sites in Nebraska varied a great deal due to moisture stress. Two of the locations had severe stress were not carried to harvest. The other two locations had moderate yields. Growers were pleased with the performance of the barley and remain interested in growing resistant barley; however drought conditions over the last several years have reduced the interest level in all spring/summer crop alternatives. Improved Management of Russian Wheat Aphid in Barley by Integration of Biological-Cultural Controls with Aphid-Resistant Cultivars The research objective of the project is to determine the cost and benefits of two new RWA resistant barley varieties (Stoneham and Sidney) compared to existing production varieties and aphid management strategies. We also have an educational component to the project with the objective to develop educational programming to promote the adoption of RWA-resistant barley and appropriate biologically intensive pest management practices as viable components of diversified cropping systems in the western High Plains. Data collection from the first growing season was completed with barley yields at Sidney in the mid 30s (bu/A). Biology of the Wheat Curl Mite and its Relation to the Epidemiology of Wheat Streak Mosaic Virus A significant effort is underway to determine the biological and ecological factors that are important to the management of the wheat curl mite and its vectored viruses, wheat streak mosaic virus and high plains virus. The major objectives of this work include: 1) Characterization and identification of the wheat curl mite biotypes. 2) Predicting wheat curl mite movement and wheat streak mosaic virus spread. 3) Using wheat curl mite populations for screening wheat lines for resistance to wheat streak mosaic virus. This project has resulted in testing and verification of the high level of virus resistance in a soon to be released variety, Mace. NORTH DAKOTA 2007 IPM Survey Maps from the 2007 IPM survey in North Dakota were uploaded onto the NDSU IPM website at the following address: (http://www.ag.ndsu.nodak.edu/aginfo/ndipm/) A state-wide survey of small grain diseases and insects continued during the 2007 growing season. Types of insects monitored include: aphids (species not distinguished), grasshoppers, wheat stem maggot and cereal leaf beetle. A total of 1,100 wheat fields were surveyed covering all 53 counties of ND during 2007. This approximately represents one field surveyed per 6,700 acres of wheat. The survey was initiated on May 29 and continued through August 9, 2007. Crops were surveyed from the 1-leaf stage through hard kernel (ripening) stage. Field scouts surveyed for insect pests of winter wheat, hard red spring wheat, and durum wheat. All other judgments of pest problems encountered in 2007 are based on reports from County Extension Agents and farmers. Background on North Dakota Survey for Diseases and Pests For the last ten field seasons, aphid monitoring has been carried out as part of a larger effort to survey diseases and insect pests in North Dakota cereals. The state is covered by 5-6 scouts who monitor fields within a county every 1-2 weeks from May through August. The insects that are monitored in cereals include: aphids, grasshoppers, and cereal leaf beetle. Results of these surveys can be found at: www.ag.ndsu.nodak.edu/aginfo/ndipm/05IPMSur/HTML/WheatIPMsurvey.htm. Background on North Dakota Autumn Survey for Wheat Midge In the mid 1980s, a major wheat midge outbreak began in northern Canada and subsequently spread in the 1990s to large areas of Manitoba, Saskatchewan, North Dakota, and northwestern Minnesota. Although wheat midge numbers have declined in recent years the North Dakota Wheat Commission is still concerned enough about wheat midge to pay for an annual soil survey that provides estimates of overwintering wheat midge populations. For this survey county agents send in soil samples in September and October from the current years wheat fields. In our lab, we examine these soil samples for wheat midge cocoons. Cocoons contain overwintering third instar larvae. When wheat midge cocoons are found, larvae are dissected to estimate parasitism levels. A map of wheat midge larval numbers, which takes into account expected mortality from parasitism, is made available to wheat farmers in February/March each year. OKLAHOMA Overview of Current Research and Accomplishments Barley Breeding Program RWA-resistant, 6-rowed, spring malting barley germplasm lines STARS 0601B - STARS 0619B, 2-rowed spring malting barley germplasm lines STARS 0620B - STARS 0636B, and 2-rowed spring feed barley germplasm lines STARS 0637B- STARS 0643B were released. These lines were developed by backcrossing 31 different sources of resistance into spring barley cultivars of each barley type, 6- rowed malt, 2-rowed malt, and 2-rowed feed. These lines were developed by USDA-ARS in Stillwater, and evaluated and selected in Idaho, Colorado and/or Nebraska with assistance of. Phil Bregitzer, USDA-ARS, Aberdeen, ID, Frank Piears, Colorado State University, and Gary Hein, University of Nebraska. Increases have been made prior to release of 10, RWA-resistant, 6-rowed, winter, feed barley germplasm lines resistant to both Greenbug and RWA. Barley cultivar was released by USDA-ARS in 2007. This cultivar was developed by USDA-ARS, Stillwater, OK and selected and evaluated by USDA-ARS, Aberdeen, ID. The main component of resistance in RWA 1758 is tolerance and is derived from STARS 9577B. A breeding program has been initiated to develop winter, hulless, feed barleys resistant to both RWA and Greenbug, adapted to Oklahoma, and suitable for ethanol production. Hulless winter barleys, selected for adaptation to OK as well as percent starch, were crossed as males to RWA and greenbug resistant lines developed by USDA-ARS in Stillwater. Evaluation of female parents is ongoing as well as crossing and backcrossing of hulless lines to selected females. 615 F2 head rows were grown in Woodward, OK in the summer of 2007. Thousands of heads were selected and hulless heads were screened to RWA and greenbug in the fall of 2007. Resistant segregates will be increased in the greenhouse in the spring of 2008. 104 hulless F3 bulks were planted in Woodward in the fall of 2008. A seedling screening test for BCOA resistance has been developed and tested for repeatability. Two replications of the Barley Core Collection (960 accessions) were screened with this new technique in the summer of 2006. Survivors were grown in pots in the greenhouse and data collected for plant height, grain yield, and yield components. Five seed each of 364 survivors were screened with BCOA in the summer of 2007. An aphid free set of identical flats was also grown. Selected survivors from the screening were rescued and, along with their matching non-infested checks, transplanted into pots in the greenhouse. Infested and non-infested pots for each line were placed side by side on greenhouse benches for increase. Plant height, grain yield, and yield components will be measured. Wheat Breeding Program Included in the guidelines in the WERA 2006 report were recommendations for establishing set plant differentials for use as screening tools, thereby eliminating one of the obvious sources of variability in our screening techniques. In order to standardize the seed source for researchers, it was determined that these plant differentials would be available to RWA researchers via Stillwater USDA-ARS, as sufficient seed is available. Seed is now available for small screening tests, and if larger amounts of seed are required for an individual program, then starter seed can be obtained from Stillwater, and seed can then be increased as needed at the various locations. In order to establish this uniform set of differentials, the suggested differential lines were screened for homogeneity for RWA1 resistance, and plants were then grown and harvested with an eye for uniform maturity, height, and other observable characteristics. Off-types were discarded. Progeny screening is being done prior to further increases. We have continued with the development of our breeding lines that are resistant to RWA1. Even though they may not be useful as germplasm or variety releases in the near future with the current prevalence of RWA2, different sources of RWA1 resistance that are due to different genes may provide additional differentials for screening against new RWA biotypes that may develop. In addition, several possible differentials resistant to RWA2, yet susceptible to RWA1, have been identified and increased. The screening of current breeding lines for resistance to RWA2 is also underway, as space and conditions allow. Several of our winter breeding lines containing Dn7 appear to be resistant to all RWA biotypes against which they have been tested. Our germplasm release STARS-0601 has also been resistant to all RWA biotypes against which it has been tested. Sorghum Breeding Program Greenbug is an important insect pest, limiting crop production throughout the world. Since 1968, the greenbug has become the predominant pest of sorghum in the Great Plains. A few sources of sorghum germplasm were identified as resistance to greenbugs at various times; however new and virulent biotypes have been able to overcome most existing sources of genetic resistance. In order to exploit new sources of greenbug resistance, we initiated a project toward a systematic evaluation of the entire U.S. collection of sorghum germplasm (over 40,000 accessions). Now screening sorghum germplasm against greenbug biotype I has been done, and the evaluation results indicate that more than 40 germplasm accessions have some degrees of resistance to greenbug biotype I. These sources of greenbug resistance in sorghum germplasm, particularly those newly identified resistant lines, should be valuable for the development of new greenbug-resistant sorghum cultivars or hybrids. Host-plant resistance has been used in many sorghum breeding programs for controlling the pest in the past. Molecular tools such as DNA markers can be used to identify and monitor the genetic components responsible for pest resistance, facilitating the breeding process. We have recently constructed a genetic linkage map for sorghum using SSR markers. With this genetic map, we have been able to identify several DNA (SSR) markers closely associated with a major QTL which conditions resistance to the greenbug. These DNA markers proved a useful tool for marker-assisted selection. The major QTL detected in this study and the tightly linked SSR markers will facilitate efficient development of resistant lines or hybrids in sorghum. RWA Biotype Diversity and Ecology Studies have been ongoing since 2006 on the ecology of overwintering RWA in diverse environments to determine if and how sexual reproduction (holocycle) occurs and its role in biotype development. This research is further supported by studying the effects of photoperiod, temperature and host on sexual form induction in the laboratory. In 2007, This research was further expanded to include the overwintering ecology of three other Diuraphis spp. endemic to the U.S.A., D. tritici, D. nodulus, and D. frequens. These species are known to go sexual in the fall and serve as positive controls in field and lab studies. Data is still being collected and conclusions not yet firm. However, it is obvious that D. noxia does not respond to environmental stimuli in the same manner as the three other Diuraphis spp. A study was conducted in collaboration with Frank Peairs and Terri Randolph to determine if there was a uniform response of RWA biotypes RWA1  RWA7 to 24 plant differentials under differing environmental conditions and locations. This study concluded that results were uniform between locations and researchers that used the same seed sources and RWA biotype sources. Future plans are to arrange collaborations with State researchers to sample sites for monitoring RWA biotypic diversity. Molecular Ecology of Cereal Aphids and their Natural Enemies To date, all results support the hypothesis that RWA was introduced once into North America, and the path of the introduction was from South Africa to Mexico, then a natural spreading of populations north into the US. The occurrence of biotypes in 2003 came after planting of Dn4 resistant wheat varieties, which began in about 1996. All data supports the hypothesis that Dn4 virulent biotypes were not introduced, but arose from the extant population. Although RWA in the US lacks genetic variation (measured by various molecular markers), it is phenotypically diverse, i.e. shows variation in its ability to injure hosts with and without plant resistant genes. Predicting the impact of predators and parasites In conjunction with collaborators from Oklahoma State University we continued research to develop a predictive population dynamics model for the greenbug. We are in the third year of a field study to quantify the spatially explicit population dynamics of the greenbug in relation to parasitism by L. testaceipes and predation by Coccinellidae and other predators. The research has potential to improve pest management practices for the greenbug in wheat. If successful, treatment decisions will be more accurate and based on improved knowledge of the potential for biological control. Remote sensing of cereal aphids In conjunction with collaborators from the Texas Agricultural Experiment Station and TerraVerde Technologies we are developing remote sensing technology to detect and monitor Russian wheat aphid infestations in winter wheat. During the previous year we documented that multi-spectral remote sensing differentiated stressed areas in production winter wheat fields caused by the Russian wheat aphid from non-stressed areas. We also documented that it is possible to differentiate stressed areas in wheat fields caused by Russian wheat aphids from areas stressed by other factors based on spatial pattern analysis and multivariate discriminant function analysis (see figure in attached file). The technology could improve pest management practices for the Russian wheat aphid in winter wheat because infestations in fields will be efficiently detected and delineated before treatment is required. SOUTH DAKOTA Overview of Cereal-Aphid Research Activities and Accomplishments: Rhopalosiphum padi (L.) (bird cherry-oat aphid) and Diuraphis noxia (Kurdjumov) (Russian wheat aphid) are common aphid pests of wheat and can co-occur at relatively high levels within wheat fields. Resistance to both aphids has been identified in several triticale accessions. We conducted experiments to identify and characterize antibiosis-type resistance to R. padi in additional triticale lines and to test R. padi-resistance levels in several backcrossed, triticale-derived lines of D. noxia-resistant wheat. Triticale accessions 6A-558, H85-734 and M86-6174 were identified with moderate levels of antibiosis to R. padi. All three accessions limited R. padi population growth relative to Arapahoe over 13 d. 6A-558 increased development time of R. padi compared to that on Arapahoe, and 6A-558, H85-734 and M86-6174 each decreased the number of nymphs produced by R. padi over 7 d. Additional tests confirmed N1185 triticale as a strong source of resistance to R. padi, and showed that Lamar wheat was not resistant to R. padi. Tests of wheat lines derived from crosses between N1185 and Lamar and then selected for resistance to D. noxia showed that three of 13 lines reduced the number of R. padi per plant, with resistance levels comparable to N1185 in two lines. Nymphiposition by R. padi measured over a 24-h period did not differ among any lines in no-choice tests. The results provide further support that triticale is a significant source of resistance to R. padi, but further work is needed to understand transference of R. padi-resistance from triticale to wheat. TEXAS Map-based cloning of greenbug resistance gene Gb3 in wheat This project aims to clone the Aegilops tauschii-derived greenbug resistance gene Gb3 from wheat (Largo source). Previously Gb3 was placed in the distal bin of wheat chromosome arm 7DL with several Gb3-linked microsatellite markers. We are conducting fine genetic and physical mapping of Gb3. Three complementary populations at diploid and hexaploid levels were used for high-resolution genetic mapping with SSRs, EST-, RFLP- or AFLP-derived STS markers. So far, 31 markers have been placed on the genetic map surrounding the Gb3 locus and a 2.0 cM interval of Gb3 is delimited by one AFLP-STS and one EST-STS marker. More markers are being developed by exploring the rice and Brachypodium distachyon whole genome sequences. Screening of an Ae. tauschii BAC library is also underway to initiate chromosome walking. Marker-assisted selection and development of greenbug-resistant wheat cultivars In the Texas Wheat Breeding Program, we are actively implementing the marker-assisted selection (MAS) strategy to expedite the breeding process. Priority traits for MAS include resistance to the greenbug, Russian wheat aphid, wheat streak mosaic virus and the wheat 1AL.1RS translocation. As a test case, one rye 1RS-specific marker and two Gb3-linked molecular markers are being used to screen large breeding populations. These markers seem to be highly predictable in selecting plants carrying the target genes. The wheat cultivar, TAM 112 carrying the greenbug resistance gene Gb3 and 1AL.1RS wheat-rye translocation is gaining increasing acreages in the Southern Plains since its release by the Wheat Improvement Program of Texas AgriLife Research at Amarillo in 2005. Molecular mapping of greenbug resistance genes in wheat and barley Molecular markers are being developed for the greenbug resistance genes Gb2, Gb6 in wheat, and Rsg1, Rsg2 in barley. These markers will be used in marker-assisted selection and development of wheat/barley germplasm with multiple resistances. Gb3-mediated host defense responses against greenbug feeding in wheat In a 2-genotype (bulked segregant R and S super pools), 3-time-point (0, 24 and 48 hours after infestation, hai), 3-replicate experiment, 18 Affymetrix GeneChips were used to investigate Gb3-mediated defense responses upon greenbug feeding. Of the ~61,000 transcripts surveyed, 47 showed significant differences in constitutive expression between the R and S pools (p = 0.05). Nearly 10,000 probe sets exhibited significant changes in expression level in both genotypes at 24hai and/or 48 hai, among which about 6,000 have putative functions. Of the 6,000 transcripts, 706 showed significantly altered expression in the R pool as compared with those in the S pool at either 24hai or 48hai or both. Analysis of expression patterns of the 706 probe sets suggested that Gb3-mediated host defense responses in wheat to greenbug feeding are more similar o plant pathogen attacks, but wounding responses are also obvious. Development of molecular markers in the greenbug The abundance and distribution of simple sequence repeats (SSRs) were explored in the EST and genomic sequences of the pea aphid and the green peach aphid. A total of 1112 newly developed, together with 40 published SSR markers were investigated for their cross-species transferability among 6 aphid species. Genetic diversity among 24 greenbug biotypes was further examined with 30 transferable SSRs. It was found that the pea aphid genome is abundant in SSRs with unique frequency and distribution of SSR motifs. Cross-species transferability of EST-derived SSRs is dependent upon phylogenetic closeness between SSR donor and target species, but is higher than that of genomic SSRs. Neighbor joining analysis of SSR data revealed host-adapted genetic divergence as well as regional differentiation of greenbug biotypes.

Please see attached file.