An agar dilution method to test the sensitivity of Glomerella cingulata, causal fungus of strawberry [Fragaria ananassa] anthracnose, to azoxystrobin
2010
Inada, M., Saga-ken. Agricultural Research Center, Kawasoe (Japan) | Yamaguchi, J. | Furuta, A.
The sensitivity of isolates of Glomerella cingulata, the causal fungus of strawberry anthracnose to azoxystrobin, was developed using an agar dilution method. MIC value of azoxystrobin were divided into 0.19-3.12 ppm and 3200 ppm (a.i.) on potato dextrose agar (PDA) containing salicylhydroxamic acid (SHAM, 1000 ppm), an inhibitor of alternative respiration. Strains with MIC 3200 ppm were regarded as resistant: (1) the protective efficacy of azoxystrobin against these strains was extremely low when tested in the bioassy, and (2) the point mutation G143A in mitochondrial cytochrome b gene was confirmed by polymerase chain reaction- restriction fragment-length polymorphism (PCR-RFLP) using the restriction enzyme ItaI. Therefore, the presence or absence of mycelial growth on PDA with 1000 ppm SHAM and 100 ppm (a.i.) azoxystrobin cultured for 4 d at 25degC can be used to determine the azoxystrobin sensitivity of this fungus relatively easier than with the conventional bioassay and PCR-RFLP.
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