Molecular Mapping of a Gene for Resistance to Stripe Rust in Wheat Variety PIW138

Stripe rust,caused by Puccinia striiformis f.sp.tritici(Pst),is one of the most damaging diseases of common wheat(Triticum aestivum L.).Wheat variety PIW138 introduced from Pakistan is resistant to the currently prevailing Pst race CYR32 in China.In this study,the bulked segregant analysis(BSA)method and simple sequence repeat(SSR)markers were used to map the stripe rust resistance gene in PIW138.The resistant and susceptible DNA bulks were prepared from the segregating F2 population of the cross between Thatcher,a susceptible variety as the female parent,and PIW138 as the male parent.The segregation of resistant and susceptible F2 plants inoculated with CYR32 indicated that single dominant gene determined the reactions of PIW138 line and temporarily designated as YrP138.Total 200 SSR primers were screened,and 4 SSR markers,Xwmc52,Xbarc61,Xgwm268,and Xgwm153,on chromosome 1B were found to be polymorphic between the resistant and the susceptible DNA bulks as well as their parents.Genetic linkage was tested on the segregating F2 population with 259 plants,including 196 resistant and 63 susceptible plants.All 4 SSR markers were linked to the stripe rust resistance gene in PIW138.The genetic distances of Xwmc52,Xbarc61,Xgwm268,and Xgwm153to the resistance gene were 29.8,6.2,6.8,and 8.2 cM,respectively.