Variations of Isozyme and Soluble Proteins among Field Populations of Plasmodiophora brassicae

Abstract

Fifteen field populations of Plasmodiophora brassicae Woronin (Williams' races 1, 4, and 9) from seven prefectures in Japan were compared by banding patterns of isozymes and soluble proteins from resting spores. When 20 enzymes were examined by electrophoresis on cellulose acetate membrane, 15 enzymes showed activity with acceptable resolution of bands and 11 of them were polymorphic, and seven electrophoretic phenotypes were detected among 15 populations. The population YAYH (Williams' race 9) from Yamaguchi Pref. had the unique banding patterns of 6-phosphogluconate dehydrogenase, hexokinase, alkaline phosphatase, and phosphoglucomutase. When soluble proteins of these populations were resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the population YAYH had five unique bands. Cluster analysis of isozymes and soluble proteins revealed two clusters between the population YAYH and other 14 populations (Williams' races 4 and 1) in dendrograms. These results indicate that a part of populations is easily distinguishable from other populations by isozyme and soluble protein analyses. However, pathogenic and nonpathogenic populations to clubroot resistant cultivars of Chinese cabbages of Japan were undistinguishable by these analyses.