Screening and identification of multi-drug resistant Botrytis cinerea strains

Eighty three Botrytis cinerea isolates from commercial strawberry were obtained,and their sensitivity to the fungicides ZJ0712,carbendazim and iprodione,which belong to different chemical groups,were determined.Among these 83 isolates,two (HZ021 and HZ054) showed multiple resistant to all of the fungicides tested.Compared to three wild-type sensitive isolates,these two multi-drug resistant (MDR) isolates did not show significant difference in mycelial growth and conidiation on potato dextrose agar (PDA) plates.Inoculation assays showed that the MDR isolates revealed highly pathogenic on cucumber leaves.These results indicate that the MDR isolates remain high survival fitness.Analyses of DNA sequences of the cytochrome b (CYT b),two component histidine kinase (OS-1),and beta-tubulin (TUB 2) genes showed that multi-drug resistance of two MDR isolates was caused by mutations in these fungicide target genes.