大麦うどんこ病菌(Erysiphe graminis DC. f. sp. hordei)の地理的分化

Fifteen cultures of barley powdery mildew fungus (Erysiphe graminis DC. f. sp. hordei) isolated in different regions of the world were inoculated to 120 barley varieties. Infection scores varied among the cultures and barley varieties, and their interactions were observed. Principal component analysis of the infection scores revealed that the cultures could be classified into three groups by first and second components (contributing 40.2% and 15.6% of the total variance, respectively), and that two Japanese cultures could be distinguished from the others isolated in Europe and North America. This indicates that the fungus is geographically differentiated in the reaction of the barley varieties to the cultures. Furthermore, East Asian barley varieties differed from European ones in their reactions to the culltures, while barley varieties from regions between East Asia and Europe showed a large genetic diversity in their reactions.