The chiral triazole fungicide metconazole has four stereoisomers, is a broad-spectrum fungicide and is widely used for controlling Fusarium head blight caused by Fusarium species. In this study, systemic assessments of metconazole stereoisomers were performed, including stereoselective toxicity toward the aquatic organism Daphnia magna, fungicidal activity and effects on fumonisin production by the pathogen Fusarium verticillioides (F. verticillioides) in relation to different conditions. The toxicity of metconazole was enantioselective, and there was a 2.1-2.9-fold difference. The activities of superoxide dismutase (SOD) and catalase (CAT) increased and decreased, respectively, after treatment with metconazole stereoisomers, and the differences were observed among the stereoisomers. Among the four stereoisomers, (1S,5R)-metconazole showed the highest fungicidal activity under all assayed conditions, and the differences ranged from 4.4 to 45.2 times. Moreover, metconazole stereoisomers can stereoselectively affect on fumonisin B1 production by F. verticillioides and abiotic factors, such as water activity and temperature, play an important role. Our study provides new insight into metconazole at the stereoisomeric level, including its toxicity, bioactivity, and effect on Fusarium species producing mycotoxins.
Keywords: Aquatic toxicity; Fumonisin B(1); Fungicidal activity; Fusarium verticillioides; Metconazole; Stereoselectivity.
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