Screening Central Asian Wheat Germplasm for Powdery Mildew Resistance and Molecular Characterization of Disease...

Powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), is a widespread and destructive wheat disease. Employing host powdery mildew (Pm) resistance genes is the most cost-effective and environmentally sustainable approach to managing this disease. In this study, we evaluated seedling resistance in 192 wheat germplasm accessions from three Central Asian countries, Kazakhstan, Kyrgyzstan, and Tajikistan, and identified five accessions with high resistance against Bgt isolate E09. Testing with 12 additional Bgt isolates demonstrated that these five accessions may contain broad-spectrum resistance. Molecular analysis using functional Pm resistance gene markers revealed that two durum wheat accessions, ZY110 and ZY117, may carry Pm68, and one common wheat accession, ZY1, may carry a candidate Pm26 allelic variant. Notably, none of the tested known Pm gene markers were detected in ZY47 and ZY95. Morphological and GISH analysis confirmed that ZY47 and ZY95 possess the rye genome (AABBRR). Molecular marker analysis of three F₂ segregating populations (ZY110 × Kronos, ZY117 × Langdon, and ZY1 × Chuanmai 42) confirmed that each contained a single resistance gene; the diagnostic markers for Pm68 co-segregated with Bgt resistance, while the marker genotypes for Pm26 co-segregated with the expected recessive inheritance model. Sequence alignment confirmed the full-length sequence of Pm68 in durum wheat accessions ZY110 and ZY117, supporting that Pm68 has been used in Central Asian wheat breeding. The candidate Pm26 allelic variant in ZY1, and the candidate sources of novel rye-derived powdery mildew resistance in accessions ZY47 and ZY95, may enrich the powdery mildew resistance gene pool for wheat breeding.