Mapping and Transfer of the Powdery Mildew Resistance Gene Pm26 from Wild Emmer Wheat to Bread Wheat

Powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), is one of the most destructive foliar diseases of wheat. Wild emmer wheat (Triticum dicoccoides, WEW), a progenitor species of bread wheat, rich in disease resistance genes, serves as a vital genetic resource for resistance breeding in bread wheat. In this study, we identified a hexaploid wheat introgression line, 7D72, derived from WEW, that exhibits high resistance to powdery mildew. An F₂ population from a cross between 7D72 and the susceptible Chinese cultivar Shiyou 20 (SY20) was used to map the underlying resistance. Bulked segregant analysis combined with DNA sequencing (BSA-Seq) and genetic linkage mapping localized a single recessive resistance locus to a 2.4-cM interval on chromosome 2BS, which overlaps with the recently cloned Pm26 locus. Sequence analysis of 7D72 confirmed that TdCNL1 and TdCNL5 are identical to the Pm26 alleles, confirming that 7D72 contains Pm26 introgressed from WEW. In addition to disease resistance, 7D72 shows improved agronomic performance, including increased grain length and thousand-kernel weight compared with its recurrent parent Han87-1. Collectively, this study represents the first successful introgression of Pm26 into common wheat without observable linkage drag, validating its function as a powdery mildew resistance source in 7D72 and providing a valuable pre-breeding germplasm that combines effective disease resistance with enhanced yield-related traits.