Molecular Identification and Validation of Three Stable QTLs Conferring Adult‐Plant Resistance to Powdery Mildew in Two Chinese Wheat Cultivars

ABSTRACT Both Yangmai 17 (YM17) and Ningmai 18 (NM18) are leading wheat cultivars in the Middle‐Lower Yangtze River Valleys wheat zone (MLYVWZ), exhibiting stable adult‐plant resistance (APR) to powdery mildew (PM) under field conditions. To elucidate the genetic mechanisms of their APR resistance, a recombinant inbred line (RIL) population derived from the cross between YM17 and NM18 was evaluated for APR in both field and greenhouse condition settings during the 2020–2022 cropping seasons. The RILs were genotyped using a 55K single‐nucleotide polymorphism (SNP) array specific to wheat. Three significant quantitative trait loci (QTLs) for PM resistance were identified on wheat chromosomes 1A, 1B and 5D, explaining 13.5%–46.7%, 6.7%–7.4% and 8.4%–15.3% of phenotypic variance, respectively. Importantly, QPm . yaas‐5D on chromosome 5D represents a novel APR locus. QPm . yaas‐1B was positioned near the interval of the pleiotropic multipathogen resistance gene Yr29/Lr46/Pm39 , while QPm . yaas‐1A was localised adjacent to the region associated with the PM resistance gene Pm3 . Furthermore, breeder‐friendly Kompetitive Allele‐Specific PCR (KASP) markers were developed for these QTLs and validated in a panel of 235 wheat cultivars/lines. The results showed that pyramiding the three resistance alleles ( QPm . yaas‐1A , QPm . yaas‐1B and QPm . yaas‐5D ) could reduce disease severity by 55.2%, highlighting their additive effect. Given the pivotal role of YM17 and NM18 as core germplasms in wheat breeding of the MLYVWZ, the identified QTLs and associated markers described here provide valuable tools for marker‐assisted selection of APR to PM, holding important application value for breeding broadly durable resistant varieties.