Identification and Characterization of Resistance Loci to Stripe Rust in Winter Wheat Breeding Line YN1813

The development and deployment of diverse resistance sources in novel wheat cultivars underpin the durable control of stripe rust. The objectives of this study were to identify quantitative trait loci (QTL) associated with stripe rust resistance in the Chinese wheat breeding line YN1813 and to provide wheat breeders with original genes with potentially durable resistance. A total of 306 F7:8 recombinant inbred lines (RIL), derived from a cross between YN1813 (infection type 0–3 and disease severity 1–36%) and the moderately susceptible landrace Chinese Spring (IT 7–9 and DS 41–65%), were assessed for stripe rust disease severity in the field at Qingshui in Gansu and Pixian in Sichuan in 2020 and 2021 following inoculation with a mixture of the currently predominant Pst races. The parents and RIL were genotyped using the Wheat 55K single-nucleotide polymorphism (SNP) array. The total length of the constructed genetic linkage map was 3896.30 cm, with an average interval of 1.30 cm between adjacent markers. Two major QTL were identified on chromosome 7B and 7D across all tested environments. QYr.hau-7B was mapped to a 2.26 cm interval between the SNP markers AX-110908486–AX-89658728–AX-109489314 on chromosome 7B, explaining 0.9% to 16.9% of the phenotypic variation. QYr.hau-7D was positioned in a 0.67 cm interval flanked by the SNP markers AX-111654594 and AX-89378255, explaining 0.4% to 21.4% of the phenotypic variation. The QTL on 7D likely correspond to the previously known gene Yr18, whereas QYr.hau-7B was presumed to be a novel gene adjacent to YrZH84 or the core part of YrZH84. SNP markers closely linked with QYr.hau-7B were converted to allele-specific quantitative PCR-based genotyping assay (AQP) markers and validated in a panel of 712 wheat accessions. The group possessing a positive allele (TT) of AQP_AX-89658728 significantly (p < 0.05) decreased the IT by 45.8% and the DS by 63.2%. QYr.hau-7B and its markers could be useful in breeding programs to improve the level and durability of stripe rust resistance.