Association Mapping for Stripe Rust Resistance in Pacific Northwest Winter Wheat

Stripe rust (Puccinia striiformis f. sp. tritici) is a globally devastating pathogen of wheat production.  In the Pacific Northwest (PNW), high-temperature adult plant (HTAP) resistance and all-stage resistance have been introduced into winter wheat breeding programs for the development of durable rust resistant cultivars.  The goal of this study is to identify QTL for these resistances through genome wide association analysis using densely distributed SNP markers in PNW winter wheat accessions. The association panel consists of 406 hard and soft winter wheat genotypes adapted to the PNW.  Field evaluation for stripe rust resistance was carried out at two locations near Pullman, WA and one location near Central Ferry, WA in 2012.  Race specific resistance was evaluated for PST-100, 114 and PSTv-11 under greenhouse conditions.  The association panel was genotyped with 9,000 SNP markers and a total of 6,841 markers were used for the trait-marker association analysis.  Principal component analysis was used to identify subpopulations, and mixed-linear models incorporating population structure and kinship was used for association analysis.  Preliminary result identified 13 significant marker-trait associations for stripe rust resistance (R² from 0.04-0.11).  Greenhouse evaluations found SNP located on 1BS and 1DS were significantly associated with resistance to PSTv-11 and SNP located on 2BL associated with resistance to PST-114.  Field evaluations associated SNP located on 2D and 4BL with HTAP resistance, but were not significant to race-specific resistance.  These data will allow breeders to better select for resistant germplasm as well as begin pyramiding different types of resistance into breeding lines.