Abstract
Genotypes of Japanese wheat cultivars at loci for resistance to the twheatgrass mildew fungus, Erysiphe graminis f. sp. agropyri, were examined using the gene-for-gene relationship. Most cultivars carried two genes, Pm10 and Pm15 for resistance to the wheatgrass mildew fungus. Almost all cultivars were non-carriers of Pm11 and Pm14. On the other hand, all isolates of the wheat mildew fungus, E. graminis f. sp. tritici, collected from various areas in Japan were non-carriers of Ppm10, Ppm11, Ppm14, and Ppm15, avirulence genes corresponding to Pm10, Pm11, Pm14, and Pm15, respectively. From these results we suggest that the population of the wheat mildew fungus had lost Ppm11 and Ppm14 before its migration to Japan.
