Identification of QTL for High-Temperature Adult-Plant Resistance to Stripe Rust in the Winter Wheat Cultivar ‘Coda'.

Wheat stripe rust (Puccinia striiformis f.sp. tritici) is a major problem facing wheat (Triticum aestivum L.) production in the Pacific Northwest. Genetic resistance to the pathogen is the most desirable form of disease control; however, resistance can be overcome due to high rates of pathogen mutation and heavy regional inoculum concentrations. Therefore, durable disease resistance, like high-temperature, adult-plant (HTAP) resistance is required. The objective of this study was to identify the HTAP resistance genes from the winter wheat cultivar Coda. A mapping population of 268 recombinant inbred lines was created developed from a cross between wheat cultivars Coda and Brundage. Genetic linkage map construction and QTL analysis were performed using Joinmap and QTL Cartographer using 171 SSR, 1275 SNP, and 232 DArT markers. Stripe rust screening was performed under natural field infection at six locations in Washington and Northern Idaho.  Infection type relative area under the disease progress curve (rAUDPC) values were 0.17 and 0.83 for Coda and Brundage, respectively.  The range in mean rAUDPC values over all locations for the RIL was 0.11 to 0.94. QTL were identified on chromosomes 1B, 3B, and 5B.  The most significant QTL associated with HTAP resistance from Coda was detected on chromosome 1B (LOD scores ranging from 16.4 to 93.0 across locations) within a 13.8 cM region flanked by Xbarc152 and Xbarc119.  Markers associated with this QTL can be used in marker-assisted selection programs to transfer this source of HTAP resistance into regionally adapted cultivars, thereby providing a durable source of stripe rust resistance.