QTL Mapping and Developing KASP Markers for High-Temperature Adult-Plant Resistance to Stripe Rust in Argentinian Spring Wheat William Som (PI 184597).

Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is a destructive disease of wheat worldwide. William Som (WS), an Argentinian spring wheat landrace, has consistently exhibited high-level resistance to stripe rust for over 20 years in our field evaluations in Washington state, USA. A previous study showed high-temperature adult-plant (HTAP) resistance in WS. To map the HTAP resistance quantitative trait loci (QTL) in WS, 114 F(5-8) recombinant inbred lines (RILs) from the cross AvS/WS were evaluated for their stripe rust response in seven field environments in Washington. The RILs and parents were genotyped with the Infinium 90K SNP chip. Four stable QTL, QYrWS.wgp-1BL on chromosome 1B (669-682 Mb), QyrWS.wgp-2AL on 2A (611-684 Mb), QyrWS.wgp-3AS on 3A (9-13 Mb), and QyrWS.wgp-3BL on 3B (476-535 Mb), were identified, and they explained 10.0-19.0%, 10.2-16.7%, 7.0-15.9%, and 12.0-27.8% of the phenotypic variation, respectively. The resistance in WS was found to be due to additive interactions of the four QTL. For each QTL, two Kompetitive allele-specific PCR (KASP) markers were developed, and these markers should facilitate the introgression of the HTAP resistance QTL into new wheat cultivars.