Identification of YrBK, an all-stage stripe rust resistance gene in a recombination-suppressed pericentromeric region of chromosome 1B in a Chinese wheat landrace

Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is a major disease constraining global wheat production. The Chinese wheat landrace Baikeheshangmai (BK) exhibits high-level, all-stage resistance (ASR) to this disease. The genetic basis of this resistance was investigated by analyzing a recombinant inbred line (RIL) population derived from cross BK × Avocet S using bulked-segregant exome capture sequencing (BSE-seq). Two resistance genes were identified: a major ASR gene, provisionally designated YrBK, and the adult-plant resistance (APR) gene Yr18. Across multiple environments, YrBK and Yr18 explained 12.47%–30.32% and 9.74%–20.56% of the phenotypic variance, respectively, and the two genes displayed a significant additive effect. Genetic mapping using a population of 4474 individuals, derived from the residual heterozygous lines, narrowed YrBK to a 0.181 cM genetic interval on chromosome arm 1BL. This genetic interval corresponds to a 56.16 Mb physical region characterized by suppressed recombination, precluding further map-based cloning. Within this interval, integrative candidate analysis combining expression profiles and SNP variation did not reveal a clear candidate from canonical resistance gene families, such as NLRs or kinases. Nevertheless, robust KASP markers co-segregating with YrBK were validated across diverse germplasm, enabling efficient marker-assisted selection. This study reports an effective genetic resource (YrBK) and provides molecular tools for marker-assisted selection. This gene will contribute to diversification of stripe rust resistance in wheat breeding.