Location: Small Grains and Potato Germplasm Research
2019 Annual Report
Objectives
The long-term objective of this project is to maintain and enhance NSGC as a worldwide resource of small grains germplasm for the research community. Specifically, during the next five years we will focus on the following objectives. Objective 1. Efficiently and effectively acquire genetic resources of small grains and their wild relatives; maintain their safety, genetic integrity, health and viability; and distribute them and associated information worldwide. 1A. Acquire crop wild relatives of wheat, barley, rice, and oat that are under-represented by taxonomy or geography and other threatened small grains germplasm. 1B. Maintain and back-up NSGC accessions. 1C. Regenerate NSGC accessions on a continuing basis with priorities determined by seed inventory and viability. 1D. Distribute on request NSGC accessions and information that meet the specific needs of researchers worldwide. Objective 2. Develop more effective genetic resource maintenance, evaluation, and characterization methods and apply them to priority small grains genetic resources; screen for host-plant resistance to virulent diseases, such as the Ug99 wheat rust strain. Record and disseminate evaluation and characterization data via GRIN-Global and other data sources. 2A. Assess putative duplicate accessions for barley and wheat. 2B. Characterize resistance to bunt and stem rust in NSGC wheat accessions. 2C. Collect remaining priority characterization data and record in GRIN-Global. Objective 3. With other NPGS genebanks and Crop Germplasm Committees, develop, update, document, and implement best management practices and Crop Vulnerability Statements for small grains genetic resource and information management. 3A. Review and update NSGC standard operating procedures for all aspects of curation and implement best management practices in coordination with other NPGS sites. 3B. Engage with small grains Crop Germplasm Committees (CGCs) to update crop vulnerability statements and identify germplasm acquisition and evaluation priorities of interest to the respective committees.
Approach
Objective 1. Acquisition priorities include the wild relatives of Triticum, Hordeum, Avena, and Oryza to fill species and ecogeographic gaps in the crop collections. Highest priority will be primary genepool relatives of these genera, identified in collaboration with the Crop Germplasm Committees (CGCs). These gaps will be addressed by collection expeditions and exchanges with other genebanks. Seed of NSGC accessions are held in medium-term storage under controlled temperature (5-6o C) and relative humidity (25%). Detailed inventory records are maintained in GRIN-Global. Seed will be provided to NLGRP for safety back up. Accessions in need of regeneration will be grown at several locations as follows: Aberdeen, Idaho in fields of the University of Idaho Research and Extension Center and in USDA-ARS greenhouses; Parlier, California at the USDA-ARS National Arid Land Plant Genetic Resource Unit; and Stuttgart, Arkansas at the USDA-ARS Dale Bumpers National Rice Research Center. Accessions will be scheduled for regeneration based on a priority matrix. Viability tests are scheduled every five years. Standard procedures for GRIN-Global Order Processing will be followed. Distributions outside of the U.S. will follow phytosanitary requirements of the recipient country, including import permits, phytosanitary certificates, and additional declarations. USDA-APHIS will be consulted regularly for the latest information on seed export. Seed shipments to other countries will be coordinated with the National Germplasm Resources Laboratory (NGRL), Plant Exchange Office. Noxious weeds will be distributed under a USDA-APHIS permit. Accessions that fall under the International Treaty for Plant Genetic Resources for Food and Agriculture will follow appropriate guidelines and will include agreement to the Standard Material Transfer Agreement by the recipient. Objective 2. Molecular markers and morphological traits will be used to develop a method to assess variation within and between NSGC wheat and barley accessions. After establishing the method, the barley and wheat collections will be sampled to measure the degree of duplication within each. Using the data from this study, verified duplicate accessions may be combined. Using genome wide association and bi-parental mapping approaches, genes for bunt and stem rust resistance will be sought within the NSGC wheat collection. Markers associated with novel resistance to the Ug99 stem rust group of races will be validated in various genetic backgrounds. Remaining priority characterization data will be collected and recorded in GRIN-Global. Objective 3. SOPs for all aspects related to acquisition, maintenance, regeneration, characterization, evaluation, and distribution will be reviewed, updated, and compiled into a complete NSGC operations manual of procedures. Through meetings and discussions with the small grains CGCs the priorities of these research communities will be identified and reflected in crop vulnerability statements and NSGC descriptors. Ongoing dialogue with the CGCs will be maintained.
Progress Report
The National Small Grains Collection (NSGC) presently holds 147,894 accessions of the small grains (wheat, barley, oat, rye, triticale, rice and related wild species). Seed distributions to scientists totaled 30,810 accession samples in 624 separate requests. Scientists from foreign countries continue to make up about one-third of the requests. This work supports Objective 1.
The wheat stem rust races originating in East Africa, collectively referred to as Ug99, pose a threat to global bread wheat production. Ug99 races have developed virulence to many resistance genes that are currently deployed in bread wheat cultivars. In support of Sub-objective 2B, ARS researchers have systematically tested NSGC winter habit bread wheat landraces for resistance to North American and Ug99 races of stem rust. Accessions that have unique resistance patterns, and do not have molecular markers linked with known resistance genes, were crossed to known susceptible cultivars. Populations derived from these crosses were used to develop genetic maps that can identify chromosomal regions and molecular markers associated with Ug99 resistance. Three accessions (PI 94439, PI 117494 and PI 479828) with unique resistance were tested against one Ug99 stem rust race. Linkage mapping results indicate new loci for adult plant stem rust resistance in PI 94439, and previously reported stem rust resistance in PI 117494 and PI 479828. Further field testing of the PI 94439 population is underway in Minnesota in collaboration with the Cereal Disease Laboratory and in Kenya in collaboration with International Maize and Wheat Improvement Center (CIMMYT) and Kenya Agriculture and Livestock Research Organization (KALRO).
Oat stem rust is a persistent threat to oat forage and grain yields. Related to Objective 2 of the project, ARS researchers made crosses with all known oat stem rust differentials using two susceptible cultivars. Populations developed from these crosses are being tested against oat stem rust races. Genetic maps derived from these populations are used in conjunction with oat stem rust trial data to detect chromosomal regions and molecular markers associated with resistance. These molecular markers can be used to identify new sources of oat stem rust resistance among NSGC accessions and assist with molecular marker introgression of known genes.
Accomplishments
1. New tools for breeding dwarf bunt resistant wheat. Dwarf bunt (DB) is a fungal disease that causes significant yield and quality losses in bread wheat. Genetic resistance offers a cost-effective method of controlling DB in bread wheat production systems, especially where organic wheat is produced. ARS researchers in Aberdeen, Idaho, selected 136 resistant accessions from the National Small Grains Collection and paired these resistant accessions with 136 susceptible accessions and 16 bunt differentials to generate a genome-wide association study (GWAS) panel. In collaboration with researchers at the University of Idaho and Utah State University, the accessions in the GWAS panel were tested with replicated field trials in a DB nursery in 2017 and 2018. The field data was used to identify accessions that were resistant to DB, and genetic information from the GWAS was used to locate chromosomal regions and molecular markers associated with resistance. Resistant accessions and molecular markers identified in this study help U.S. wheat breeders incorporate DB resistance into adapted bread wheat cultivars.
Review Publications
Bonman, J.M., Bockelman, H.E., Hijmans, R.J., Hu, G., Esvelt Klos, K.L., Gironella, A.N. 2018. Evaluation of grain ß-glucan content in barley accessions from the USDA National Small Grains Collection. Crop Science. 59(2):659-666. https://doi.org/10.2135/cropsci2018.10.0606.
Duke, S.H., Henson, C.A., Bockelman, H.E. 2018. Comparisons of modern United States and Canadian malting barley cultivars with those from pre-Prohibition: III. Wort sugar production during mashing. Journal of American Society of Brewing Chemists. 76(2):96–111. https://doi.org/10.1080/03610470.2017.1402582.
Duke, S.H., Henson, C.A., Vinje, M.A., Walling, J.G., Bockelman, H.E. 2019. Comparisons of modern United States and Canadian malting barley cultivars with those from pre-Prohibition: V. Bmy1 intron III alleles and grain beta-amylase activity and thermostability. Journal of American Society of Brewing Chemists. 77(1):62-68. https://doi.org/10.1080/03610470.2018.1546110.
Henson, C.A., Duke, S.H., Bockelman, H.E. 2018. Comparisons of modern United States and Canadian malting barley cultivars with those from pre-Prohibition: II. Amylolytic enzyme activities and thermostabilities. Journal of American Society of Brewing Chemists. 76(1):38-49. https://doi.org/10.1080/03610470.2017.1396843.
Henson, C.A., Duke, S.H., Bockelman, H.E. 2018. Comparisons of modern United States and Canadian malting barley cultivars with those from pre-Prohibition: IV. Malting quality assessments using standard and nonstandard measures. Journal of American Society of Brewing Chemists. 76(3):156-168. https://doi.org/10.1080/03610470.2018.1492818.
