Mapping, validation, and development of markers for stripe rust resistance loci in wheat cultivar Lanhangxuan 122

The utilization of stripe rust resistance genes or quantitative trait loci (QTL) is an effective strategy to diversify resistance sources and delay the breakdown of rust resistance in the Longnan region, a hot spot for stripe rust in China. Wheat cultivar Lanhangxuan 122 has shown high adult-plant resistance (APR) to stripe rust in this region. In this study, a population comprising 221 recombinant inbred lines (RILs) derived from a cross between Lanhangxuan 122 and susceptible cultivar Huixianhong was evaluated for APR in field trials at two locations in the 2021-2024 cropping seasons. Bulked segregant exome sequencing (BSE-Seq) combined with composite interval mapping (CIM) analysis was employed for genetic analysis. Three stable loci, QYr.L122-1BL, QYr.L122-2DL, and QYr.L122-3BL, were identified with average phenotypic variance of 7.4%, 16.1%, and 7.8%, respectively. The closely linked SSR and KASP markers were developed for each locus. Candidate genes were identified within the mapped intervals of the three loci. Furthermore, through field evaluation combined with marker-assisted selection (MAS), 32 advanced wheat lines with all three QTL along with high-quality were selected from crosses involving Lanhangxuan 122 and other elite wheat cultivars such as Shiyou 4045, Zhoumai 38, and Zhoumai 18. These lines show potential for release as new cultivars or parents in breeding for durable resistance to stripe rust. This study provides information on stable stripe rust loci, candidate genes, and available KASP markers for wheat stripe rust resistance breeding.