Virulence variability among isolates of Blumeria graminis f. sp. tritici from wheat in Iran

Powdery mildew of wheat, caused by Blumeria graminis f. sp. tritici, is one of the important diseases of wheat in Iran. This study was conducted to determine variability of virulence among isolates of the fungus from various regions and to detect resistant genes useful in breeding programs. Fifty-five isolates of B. graminis f. sp. tritici, collected from Golestan, Mazandarn, Ardabil, Tehran, and Fars provinces, were tested on 17 differential wheat lines/cultivars with major resistant genes to powdery mildew to evaluate their virulence. Wheat seedlings were grown in a greenhouse and inoculated at the one-leaf stage of growth. Development of powdery mildew was recorded at 12 days after inoculation. Thirty-nine physiological races were detected. Cultivars Axminster and Ronso, carrying Pm1 and Pm 4b genes and cultivars Apollo and Normandi carrying combination of Pm 2+4b+8 and Pm 1+3+9 genes, respectively, were resistant against most of the isolates. Powdery mildew-resistant genes in these cultivars could be incorporated into high-yielding, powdery mildew-susceptible wheat cultivars.