Genetic Analysis and Molecular Mapping of Stripe Rust Resistance Gene in Wheat Cultivar Zhongliang 21

Wheat (Triticum aestivum L.) cultivar Zhongliang 21 displays resistance to 7 prevalent Puccinia striiformis f. sp. tritici (Pst) races from China. The resistance gene(s) carried by this cultivar was identified using molecular markers in combination with phenotypic evaluation. Seedlings of the F₁, F₂, and BC₁ generations from the cross between Zhongliang 21 (resistant) and Mingxian 169 (susceptible), as well as the parents, were inoculated with Pst race CYR30 in greenhouse, and the resistance was evaluated 15-16 d after inoculation. The results showed that the stripe rust resistance in Zhongliang 21 was conferred by a single dominant gene, which was designated tentatively Yrzhong21. Based on bulked segregant analysis, 10 simple sequence repeat (SSR) markers located on chromosome 5AL were identified to be linked to Yrzhong21, of which Xgwm186 andXbarc165 were the closest flanking markers with genetic distances of 7.4 and 2.7 cM, respectively. In combination with analyses of chromosomal location, reactions to various pathotypes, and pedigree, Yrzhong21 was deduced as a novel gene resistant to stripe rust. Eighteen wheat cultivars (lines) in Zhongliang series were further screened with markers Xgwm186 andXbarc165. Only 3 cultivars produced identical banding pattern to that of Zhongliang 21. This result primarily indicates that only 17% of Zhongliang cultivars (lines) might carry Yrzhong21. This resistance gene is promising in wheat breeding programs for strip rust resistance.