Sensitivity ofFusarium graminearum to fungicide JS399-19:In vitro determination of baseline sensitivity and the risk of developing fungicide resistance |
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Authors: | Yu Chen Hengkui Li Changjun Chen Mingguo Zhou |
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Institution: | (1) College of Plant Protection, Nanjing Agricultural University, 210095 Nanjing, China;(2) Dept. of Textile of Apparel, Anhui University of Technology and Science, 241000 Wuhu, China |
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Abstract: | The baseline sensitivity ofFusarium graminearum Schwade teleomorph =Gibberella zeae (Schweinitz) Petch] to the fungicide JS399-19 (development code no.) 2-cyano-3-amino-3-phenylacrylic acetate] and the assessment
of risk to JS399-19 resistancein vitro are presented. The mean EC50 values for JS399-19 inhibiting mycelial growth of three populations of wild-typeF. graminearum isolates were 0.102±0.048, 0.113±0.035 and 0.110±0.036 μg ml−1, respectively. Through UV irradiation and selection for resistance to the fungicide, we obtained a total of 76 resistant
mutants derived from five wild-type isolates ofF. graminearum with an average frequency of 1.71 × 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 EC50 values of 1.5–15.0 μg ml−1, 15.1–75.0 μg ml−1 and more than 75.0 μg ml−1, 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. Although the resistant mutants appeared to have comparable pathogenicity to their wild-type parental
isolates, they showed decreased mycelial growth on potato-sucrose-agar plates and decreased sporulation capacity in mung bean
broth. Nevertheless, most of the resistant mutants possessed fitness levels comparable to their parents and had MR or HR levels
of resistance. As these studies yielded a high frequency of laboratory resistance inF. graminearum, appropriate precautions against resistance development in natural populations should be taken into account.
http://www.phytoparasitica.org posting August 7, 2008. |
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Keywords: | Crop resistance disease management Fusarium head blight Gibberella zeae resistance stability |
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