Mapping of Stripe Rust Resistance QTLs in Soft Red Winter Wheat.

Stripe rust, caused by Puccinia striiformis f. sp. tritici (PST), is an important foliar disease of soft red winter wheat (SRWW) in the eastern U.S. However, very few resistance genes have been characterised in this germplasm pool. The SRWW lines VA96W-270 and VA96W-270V (a variant of VA96W-270) are known to be resistant to stripe rust race PST-100.  To elucidate the genetic basis of stripe rust resistance, each resistant line was crossed to a susceptible cultivar, Coker 9835. The two recombinant inbred line (RIL) populations (VA96W-270 x Coker 9835 and VA96W-270V x Coker 9835) were evaluated for stripe rust resistance under field conditions over a three-year period. Resistance was estimated to be controlled by at least two race-specific, adult plant resistance genes. Simple sequence repeat (SSR) marker analysis is being performed on these RILs with an aim to construct genetic linkage maps and to identify quantitative trait loci (QTL) responsible for stripe rust resistance in these RIL populations. Following the parental screening with SSRs, a bulked segregant analysis (BSA) was performed on bulked DNA from five resistant and five susceptible individuals in the VA96W-270 x Coker 9835 population. Genotyping the entire population with stripe rust linked SSRs and mapping are currently underway. The presentation outlines some of the preliminary findings from this research.