Evaluation of powdery mildew resistance and molecular detection of resistance genes in an international wheat collection

Wheat powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), is a widespread airborne fungal disease which seriously threatens wheat production worldwide. Resistance to the disease can be lost quickly due to the limited number of resistance genes in wheat varieties and the high variation of powdery mildew pathogen. Therefore, it is critical to explore new resistance genes to breed durable resistant wheat varieties. The objectives of this study were to evaluate powdery mildew resistance at the seedling and adult stages, and to detect the presence of Pm genes in 332 germplasms from an international wheat collection using molecular markers. It was determined that only seven, four, and two accessions were resistant to Bgt races E09, E15, and A13, respectively. All tested accessions were fully susceptible to Bgt race A44 at the seedling stage. A total of 34 accessions were resistant at the adult plant stage. Molecular tests of the known Pm genes showed that 107 accessions did not contain any Pm genes. Additionally, 119 accessions were found to carry Pm38, 113 may have carried Pm8, 27 may have carried Pm21, 22 may have carried Pm60, 16 may have carried Pm24, 16 may have carried Pm41, 5 may have carried Pm5e, 2 may have carried Pm46, and Pm2a was not detected. By characterizing the resistance of an international wheat collection to powdery mildew, this study provides new sources for expanding genetic diversity and developing new wheat varieties with durable resistance to powdery mildew.