Difficulty to establish vegetative compatibility of Japanese isolates of Verticillium dahliae Kleb. using melanin-synthesis deficient mutants.

Japanese isolates of Verticillium dahliae were formerly designated as tomato pathotype and non-tomato pathotype by pathogenicity tests. We attempted to classify 18 Japanese isolates based on vegetative compatibility. Only three isolates of the tomato pathotype induced compatible alm-brm mutants. A non-secreting brm mutant was not induced from isolate of the non-tomato pathotype. Complementation was not achieved by a pair of mutants from the tomato pathotype and those from the non-tomato pathotype. From these results, Japanese isolates of V. dahliae could not be separated into any vegetative compatibility groups using melanin synthesis-deficient mutants.