Molecular Characterization of a Stripe Rust Resistance Gene from Wheat Line S2199 and Its Allelism with Yr5

Abstract

Yellow rust, caused by Puccinia striiformis f. sp. tritici (PST), is one of the most devastating diseases in common wheat ( Triticum aestivum L.) worldwide. Molecular markers are powerful tools in marker-assisted selection, gene pyramiding, and gene cloning of important crop traits, especially for disease resistance. The objectives of this study were to develop tightly linked molecular marker of a yellow rust resistance gene against the prevalent Chinese races of PST in an improved wheat line S2199 and to characterize its allelism with Yr5. Genetic analysis indicated that a single dominant gene was responsible for the yellow rust resistance in S2199, which was temporarily designated as YrS2199. By screening 1,856 pairs of SSR primers, 2 markers, Xdp269 and Xgwm120, were linked to the yellow rust resistance gene with genetic distance of 0.7 and 11.0 cM, respectively. The SSR marker Xgwm120 has been genetically and physically mapped on 2BL chromosome arm in wheat. Using Chinese Spring nullisomic-tetrasomics, ditelosomics, and deletion lines of homoeologous group 2, Xdp269 was physically mapped on the terminal bin (0.89–1.0) of chromosome arm 2BL. Both allelism test of 700 F 2 plants from the cross YrS2199/Yr5 and seedling tests of YrS2199 and Yr5 on 14 PST isolates indicated that YrS2199 and Yr5 were likely to be the same gene or allelic genes. The YrS2199 tightly linked to SSR marker Xdp269 can be used as a potential tool for cloning the yellow rust resistance gene or for marker assisted breeding program.