Fine mapping of a novel powdery mildew resistance gene PmDM8 derived from a cultivated emmer (Triticum dicoccum).

Key message: A novel powdery mildew resistance gene PmDM8, originated from cultivated emmer wheat accession JingDM8, was finely mapped to a 452.6-kb genomic interval on chromosome arm 6BL. Powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), is a major threat to production of wheat (Triticum aestivum L.). Identifying new disease resistance genes is essential for protecting wheat from this disease. Cultivated emmer (T. dicoccoides), a type of tetraploid wheat, contains many disease resistance genes that can improve common wheat. The cultivated emmer accession JingDM8 is immune to the Bgt isolate E09. Genetic analysis revealed that the resistance to powdery mildew in JingDM8 was controlled by a single dominant gene, temporarily designated PmDM8. Using bulked segregant analysis (BSA) and molecular mapping, PmDM8 was located at the terminal region of chromosome 6BL, flanked by markers Xhenu580 and Xhenu770, within a genetic interval of 0.14 cM, corresponding to a 453-kb genomic region in the Zavitan reference sequence (v2.0). By comparing gene sequences and functions, we identified the gene TRIDC6BG066670 as a likely candidate for PmDM8. This gene encodes a leucine-rich repeat receptor-like protein kinase. The expression of this candidate gene increased significantly following Bgt infection in the resistant parent JingDM8. Comparisons with previous studies suggested that PmDM8 is a novel powdery mildew resistance gene. These results facilitate cloning of PmDM8 and demonstrate its potential for enhancing powdery mildew resistance in wheat breeding programs.