Sensitivity of Fusarium graminearum to Fungicide S399-19:in vitro Determination of Baseline sensitivity and the Risk of Developing Fungicide Resistance
【摘要】：正This paperpresents the baseline-sensitivity of Fusarium graminearum to the fungicide JS399-19 (development code number, 2-eyano-3-amino-3-phenylacrylic acetate) and the assessment of risk to JS399-19 resistance in vitro. The mean EC_(50) values for JS399-19 inhibiting mycelial growth of three populations of wild-type E graminearum isolates were 0.102±0.048, 0.113±0.035 and 0.110±0.036 μg/ml, respectively. Through ultra-violet (UV) irradiation and selection for resistance to the fungicide, we obtained a total of 76 resistant mutants derived from five wild-type isolates of E graminearum with the average frequency of 1.67×10~(-7) % and 3.5%, respectively. These mutants could be divided into three categories of resistant phenotypes with low (LR), moderate (MR) and high (HR) level of resistance, determined by the EC~(50)values of 1.5-15.0μg/ml, 15.1-75.0μg/ml and more than 75.0μg/ml, respectively. There was no positive cross-resistance between JS399-19 and fungicides belonging to other chemical classes, such as benzimidazoles, ergosterol biosynthesis inhibitors and strobilurins, suggesting that JS399-19 presumably has a new biochemical mode of action. Though the resistant mutants appeared to have comparable pathogenicity to their wild-type parental isolates, they showed decreased mycelial growth on PSA plates and decreased sporulation capacity in mung bean broth. Nevertheless, most of the resistant mutants possessed fitness levels comparable to their parents and belonged to MR or HR levels of resistance. As these studies yielded a high frequency of laboratory-resistance in F.graminearum, appropriate precautions against resistance development in natural populations should be taken into account.