Fine mapping of a powdery mildew resistance gene PmCWI16926 from cultivated emmer wheat

Wheat powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), severely threatens global wheat production. In this study, the cultivated emmer accession CWI16926-4Y exhibits high-level and broad-spectrum resistance at both seedling and adult plant stages. Genetic analysis reveals that the powdery mildew resistance in CWI16926-4Y is controlled by a single dominant gene, designated PmCWI16926. Employing bulked segregant RNA analysis combined with high-density mapping, a 590 kb physical interval (21.70-22.29 Mb) on chromosome 2BS is delimited and referenced against the durum wheat cv. Svevo genome assembly. Within the interval, we identify two NLR-type genes, with TRITD2Bv1G010140 emerging as the most promising candidate based on pathogen-induced expression and a unique haplotype. Moreover, we validate four co-segregated markers and a gene-specific marker, enabling marker-assisted transfer of PmCWI16926 into elite cultivars in breeding. This study expands the repertoire of deployable Pm genes from emmer wheat and provides additional genetic tools for resistance breeding. The study identifies a single dominant, broad-spectrum powdery mildew resistance gene from cultivated emmer wheat, nominates a likely NLR candidate, and validates co-segregating markers to enable marker-assisted breeding in elite cultivars.