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United States Department of Agriculture

Agricultural Research Service


Location: Wheat Genetics, Quality Physiology and Disease Research

2013 Annual Report

1a. Objectives (from AD-416):
Investigate the genetic mechanisms by which the plant hormones abscisic acid (ABA) and gibberellin (GA) control pre-harvest sprouting stand establishment, and drought and cold tolerance in wheat and model organisms. Develop and utilize molecular markers for the western region wheat and barley breeding programs for resistance to stem rust, other biotic and abiotic stresses, and end-use quality. Develop wheat cultivars with durable resistance to stripe rust, stem rust, soilborne diseases, cold and drought, and improved end-use quality for Western Region cropping systems using wheat germplasm resources from the USDA-ARS National Small Grains Germplasm Collection (NSGC) and other national and international sources.

1b. Approach (from AD-416):
Determine whether ABA sensitivity controls grain dormancy and tolerance to preharvest sprouting. Determine whether degree of drought tolerance and cold tolerance tend to correlate with each other and depend upon ABA sensitivity. Determine how GA signaling controls seed dormancy and plant height. Identify and use new and existing molecular markers linked to genes for biotic stress resistance, specifically for stripe rust resistance. Identify and use new molecular markers for genes linked to abiotic and end-user quality. Establish and use high-throughput molecular marker analysis systems to track the segregation of important genes in wheat and barley breeding programs. Characterize core wheat germplasm sets for use in identifying haplotypes important in Western Regional germplasm adaptation. Use molecular markers to link genotypes to phenotypes while maintaining critical haplotypes for enhancement, disease resistance and end-use quality in Western Region wheat breeding programs. Identify new sources of genes giving superior end-use quality, disease resistance, and resistance to cold and drought. FY09 Program increase. Add 0.00 SY.

3. Progress Report:
This is the final report for this project, which has been replaced by new project 5348-21000-030-00D, Genetic Improvement of Wheat and Barley for Resistance to Biotic and Abiotic Stresses. For additional information, see the new project report. Obective 1A addresses whether response to the plant hormone ABA provides higher wheat grain dormancy and preharvest sprouting tolerance. ABA hypersensitive ZakERA8 mutants cause higher seed dormancy in white-kerneled Zak, while ABA insensitive ScABI mutants result in decreased seed dormancy in red-kerneled Scarlet. While ZakERA8 has better preharvest sprouting tolerance than normal Zak, the ScABI lines have just as much preharvest sprouting tolerance as hard red Scarlet. Thus, loss of ABA sensitivity isn't enough to cause Scarlet to loose preharvest sprouting tolerance. Objective 1B examined whether ABA controls wheat resistance to drought stress. ABA hypersensitive mutant Warm4 causes decreased transpiration rate, increased water use efficiency, and warmer canopy temperatures. Objective 2A Identify and use molecular markers for biotic stress resistance, abiotic stress and end-use quality. The Western Regional Small Grains Genotyping laboratory coordinated the Washington state contribution to single-nucleotide polymorphism (SNP) discovery efforts using the Illumina SNP platform for 9000 and 90,000 wheat SNPs. Objective 2B Datapoints scored for the past 12 months are described in the annual progress report for 5348-21000-030-00D. Objective 2C Characterize core wheat germplasm for use in identifying haplotypes important in Western Regional germplasm: Germplasm from the NSGC that was screened in Kenya for UG99 resistance was characterized with SSR and SNP markers, a molecular phylogeny was developed which was used to indicate novel resistance germplasm. Objective 3 Develop wheat germplasm and cultivars adapted to Western Region cropping systems with resistance to stripe rust, soilborne disease, cold, drought, and with improved end-use quality and to coordinate the Western Regional Cooperative Wheat Nurseries. The release of the winter club wheat 'Cara' cultivar was published in 2012. ARS-Selbu soft white winter wheat and ARS-Chrystal winter club wheat were released. All three wheats have excellent resistance to predominant races of stripe rust and excellent end use quality. The Western Regional Nurseries were evaluated at ten locations in the Northwest. Data was collected on agronomic traits, resistance to stripe, stem and leaf rust, and cold tolerance. This work benefits wheat growers and end users because competitive soft wheat cultivars can be grown with reduced inputs and marketed as premium quality products.

4. Accomplishments
1. ZakERA8 increases seed dormancy in white wheat. Whole grain white wheat is tastes better and mills better than the red wheat currently used for bread. The problem is that white wheat has less dormancy and is more likely to undergo preharvest sprouting if rain triggers germination before harvest. ARS Researchers in Pullman, Washington, found that ABA-hypersensitive mutant ZakERA8 has increased seed dormancy, but loses seed dormancy rapidly enough to so that it does not cause poor germination when sown in fall or spring. This mutation will reduce the risk of preharvest sprouting without causing poor seedling emergence in white wheat.

2. Wheat with resistance to the cereal cyst nematode, Heterodera avenae. The problem is that cereal cyst nematodes attack the root systems of wheat, thereby reducing yields by interfering with nutrient uptake. Spring wheat cultivars were screened for tolerance and resistance to these nematodes and sources of resistance identified in four breeding lines and one commercial cultivar. The wheat plants identified will provide new sources of resistance for wheat breeders. This should improve yields – especially under drought conditions when healthy root systems are particularly important.

Last Modified: 05/21/2017
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