Fine mapping and breeding application of powdery mildew resistance gene in wheat breeding line N278

Powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), severely impacts wheat production. The deployment of effective resistance genes through marker-assisted selection (MAS) provides an efficient strategy for sustainable management of this disease. In this study, the wheat breeding line N278 showed broad-spectrum resistance to all 24 Bgt isolates at the seedling stage and maintained resistance at the adult-plant stage for five consecutive years. Genetic analysis showed that the resistance was controlled by a single dominant gene, temporarily named PmN278. Bulked segregant RNA-Seq (BSR-Seq) in F2:3 families combined with large-scale molecular marker genotyping of 8,000 F3 individuals delimited the resistance locus to an 882.36 kb interval on chromosome arm 5BL according to Chinese Spring reference genome (v2.1). Sequence alignment and molecular marker detection indicated that the resistance locus identified in N278 corresponds to the previously cloned powdery mildew resistance gene Pm36, which encoded a tandem kinase with a transmembrane domain (WTK7-TM). Gene expression profiling revealed a significant induction of Pm36 transcripts at 48 hours post-inoculation (hpi) with Bgt isolate E09, corresponding to the early stage of fungal infection development in N278. Furthermore, MAS was used to transfer Pm36 into the susceptible commercial cultivar Shixin 828, generating the resistant advanced line NS24. Field evaluation over three consecutive growing seasons showed that NS24 retained stable powdery mildew resistance without obvious negative effects on major agronomic traits. These results validate the effectiveness of Pm36 in an elite Chinese wheat breeding background and provide valuable resources for the deployment of broad-spectrum powdery mildew resistance in wheat improvement.