Effect of Prochloraz on Growth and Development of Prochloraz-sensitive Strain and its Resistant Mutants in Fusarium fujikuroi

Effects of prochloraz on gorwth and development and hyphal morphology of Fusarium fujikuroi were studied by bioassay technique.The results indicated that prochloraz could significantly inhibit on mycelial growth,spore germination and germ tube elongation,but had no effect on sporluation capacity.The mycelial growth of parental sensitive strain was completely inhibited at 0.5 μg/mL of prochloraz,but all the resistant mutants at different levels of resistance could grow at the same concentration. The inhibition of prochloraz on colonial spreading of resistant mutants gradually reduced with the increase of resistant factor from 24 to 112. For mycelial growth of strain sensitive to prochloraz,the EC50 value was 0.047 μg/mL and the minimum inhibitory concentration (MIC) was 0.5 μg/mL. Prochloraz at 20 μg/mL exhibited 100% and 84.1% ~89.0% inhibition rate on spore germination of the parental sensitive strain and its resistant mutants,and also exhibited 100% and 58.5％ ~65.8% inhibiting rate on germ tube elongation,which showed that,compared with the parental sensitive strain,the sensitivity of the resistant mutants to prochloraz significantly reduced in mycelial growth,spore germination and germ tube elongation stages. After 10 h-exposure to 10 μg/mL of prochloraz,the hyphal tip of the parental sensitive strain and resistant mutants showed abnormal swelling shape. And many small embranchment appeared on the hyphae of resistant mutants,which revealed that prochloraz could not inhibit the sub-hyphae growth of the resistant mutants completely.