Identification of powdery mildew resistance genes in common wheat (Triticum aestivum L). II. French cultivars

Major genes for resistance to the wheat powdery mildew pathogen, Erysiphe graminis f sp tritici, were analysed in 35 French wheat cultivars and in part in their parents. Cultivars were tested with a set of differential pathogen isolates which had specific interactions for each host line. The results were supplemented by cytological investigations and by consideration of pedigrees. Eighteen cultivars showed susceptible reactions. The remainder formed 9 groups with 1 or 2 resistance genes. Of the 5 known resistance genes present, Pm2 was the most common (in 5 cultivars), followed by Pm4b and Pm6 (each present in 4 cultivars), Pm5 (3 cultivars) and Pm8 (2 cultivars). In addition, an unknown resistance, tentatively designated Mlar, was identified in 3 cultivars.