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Fungicide Sensitivity and Phylogenetic Relationship of Anthracnose Fungi Isolated from Various Fruit Crops in Japan

Anthracnose diseases of fruit crops are mainly caused by Colletotrichum gloeosporioides and C. acutatum. In these Colletotrichum species, intra- and interspecific variation in fungicide sensitivity has been reported; however, the relationship between fungicide sensitivity and molecular phylogeny has not been analyzed. Fifty-one isolates from 10 fruit crops, acacia, and tea were tested for their sensitivities to thiophanate-methyl, diethofencarb, and iminoctadine-triacetate, and their internal transcribed spacer (ITS) and 5.8S regions of rDNA were analyzed. C. gloeosporioides isolates were divided into sensitive, less sensitive, intermediate resistant, or resistant to the three fungicides. In contrast, C. acutatum isolates were all less sensitive. In molecular phylogenetic analyses, C. gloeosporioides isolates fell into the same genetic group, whereas C. acutatum isolates were placed into two genetic groups. Although phylogenetic relationship was not closely related to fungicide sensitivity, the isolates of C. gloeosporioides most resistant to iminoctadine-triacetate were found in the same phylogenetic subgroup.