Induction and Characterization of Iprodione-resistant Mutantsof Cladosporium fulvum

Sensitivity of three phenotypes of Cladosporium fulvum isolates,namely benzimidazole sensitive-diethofencarb resistant (BenS-DieR),benzimidazole resistant-diethofencarb sensitive(BenR-DieS)and benzimidazole resistant-diethofencarb resistant(BenR-DieR),to different classes of fungicides was determined.The results showed that there was no relationship between the sensitivity of C. fulvum to benzimidazole,diethofencarb and to other fungicides. Activity of mycelial growth inhibition of the 16 fungicides against C.fulvum was procymidone＞vinclozolin＞iprodione＞tebuconazole＞chlorothalonil＞ pyrimethanil＞kresoxim-methyl＞mancozeb＞8-hydroxyquinoline copper (Ⅱ) salt＞propiconazol＞ difenoconazole＞azoxystrobin＞mepronil＞dimethomorph＞boscalid＞triadimefon.Activity of spore germination inhibition was kresoxim-methyl＞procymidone＞chlorothalonil＞vinclozolin＞mepronil＞8-hydroxyquinoline copper (Ⅱ) salt＞iprodione＞mancozeb＞azoxystrobin＞boscalid＞pyrimethanil＞tebuconazole＞propiconazol＞difenoconazole＞triadimefon＞dimethomorph. A total of 17 iprodione-resistant mutants was isolated through UV irradiation with a mutation frequency of 4.5×10-7. Among them,the percentage of low level resistant mutants,moderate level resistant mutants,and high level resistant mutants was 17.65%,70.59% and 11.75%,respectively. All mutants showed cross-resistance to procymidone and vinclozolin. No significant difference in sensitivity was detected between these mutants and their parent to other fungicides such as benzimidazoles,DMIs and QoIs. There was no significant difference in growth,sporulation and pathogenicity between mutants and their parent too. However,these mutants were more sensitivity to osmotic stress than their parent.