Determinaton of Resistance Sources to Powdery Mildew (Blumeria graminis f.sp. tritici) in Iranian Bread Wheat Germplasm

A total of 1198 Iranian accessions of Bread Wheat Collection of National Plant Gene Bank of Iran were evaluated and screened for resistance to powdery mildew disease. The genetic materials were evaluated separately in three different sets, each comprising about 400 accessions, in three disease hot spots of Sari, Moghan and Gorgan under natural infection of the disease. The resistant accessions were purified leading to 168 lines which were then evaluated again in three hot spots for resistance under the field condition. Different number of resistant genotypes were determined in each location, however, two genotypes B1G11 (From Khorasan) and B2G6 (From Ilam) were resistant in all three location. The pathogen isolates were collected from different regions and purified by single clones and were inoculated on the differential cultivars. Three pathotypes were determined, all had virulence factors for Pm3b, Pm4a, Pm5, Pm6 and Pm7. The pathotypes lacked virulence factor for Pm2, Pm4b and Pm17. The resistance of 165 genotypes was also evaluated with these three pathotypes at seedling stage in greenhouse. Eighty-nine genotypes were resistant to three pathotypes. Forty-two genotypes had different reaction patterns compared to differential varieties suggesting different resistance gene(s) other than those in differential varieties. The results of this research indicated the potential of Iranian bread wheat germplasm as a source for determination of resistant genotypes to powdery mildew disease.