Fine mapping and genetic dissection of PmCWI16926, a broad-spectrum powdery mildew resistance gene from cultivated emmer wheat

Wheat powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), severely threatens global wheat production. Cultivated emmer wheat, a direct progenitor of common wheat, harbors rich genetic diversity and represents a valuable source of novel resistance genes. In the present study, the cultivated emmer accession CWI16926-4Y exhibited high-level and broad-spectrum resistance at both seedling and adult plant stages. Genetic analysis revealed 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, PmCWI16926 was delimited to a 590 kb physical interval (21.70-22.29 Mb) on chromosome 2BS of the durum wheat cv. Svevo genome. Comparative analysis confirmed its distinction from nine previously reported loci on 2BS. Within the interval, two NLR-type genes were identified, with TRITD2Bv1G010140 emerging as the most promising candidate based on pathogen-induced expression and a unique haplotype defined by three nonsynonymous SNPs absent in other resistant and susceptible genotypes. Moreover, four co-segregated markers and a gene-specific marker KASP689-1 were validated, 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 new genetic tools for durable and precise resistance breeding.