Genetic Analysis and Molecular Mapping of Stripe Rust Resistance Gene in Wheat Line M8003-5

Wheat (Triticum aestivum L.) line M8003-5 is selected from the hybrid progenies of the common wheat variety Chinese Spring and Secale cereale L., which exhibits not only resistance to Puccinia striiformis West. f. sp. tritici (Pst) but also high yield, early maturity, and resistance to drought. To develop molecular markers for Pst resistance gene(s) in M8003-5, a segregation population was constructed by crossing M8003-5 with a highly susceptible variety Mingxian 169. Seven prevalent Pst races in China were inoculated in greenhouse at seedling stage phenotyping individuals from the F₁, F₂, and F₃ generations. The results showed that M8003-5 was resistant to all races tested, whereas Mingxian 169 was highly susceptible to all inoculates. Genetic analysis indicated that the resistance of M8003-5 against Sun11-4 was conferred by a dominant gene, which was tentatively designated as YrM8003. This gene was linked to simple sequence repeat (SSR) markers Xbarc5, Xwmc463, Xwmc405, Xbarc126, Xgwm295, Xgwm44, Xwmc702, Xwmc438, Xwmc121, Xgwm111, and Xbarc128, which were all located on chromosome arm 7DS. The closest flanking makers were Xwmc702 and Xwmc438 with the genetic distances of 3.5 cM and 4.3 cM, respectively. Gene YrM8003 differs from any other known Pst resistance genes on 7DS, and is probably a novel gene. This gene is primarily inferred to originate from S. cereale based on analyses of pedigree and molecular markers data. Markers Xwmc702 and Xwmc438 were used to test 43 wheat cultivars from Huang-Huai Winter Wheat Region, and 20% cultivars were amplified with the target bands. These cultivars require further tests to validate the presence of YrM8003.