Identification of secondary metabolites in mycoparasites Fusarium strains and antifungal activity of fusaric acid against Plasmopara viticola.

Fusarium delphinoides M1, F. brachygibbosum M2, F. pseudonygamai M10, M12_1 and Fusarium species novo M12_2 have been reported as mycoparasites of Plasmopara viticola, a causal agent of downy mildew disease of grapes. This study focused on screening of biocontrol potential of secondary metabolites produced by Fusarium strains using UHPLC-QTOF-MS coupled with UNIFI software. Furthermore, multivariate analysis was performed to analyze discriminant metabolites. The thirty-nine metabolites were identified based on their precursor, fragments ions matching with fungal secondary metabolite database. Among the metabolites, the identity of fusaric acid was the most common and dominant metabolite in extract of five strains. Leaf disc bioassay showed that extract of these strains inhibited >80% sporangia production in P. viticola and IC₅₀of fusaric acid was <0.61 µG/mL against P. viticola. Fusarium strains can be further explored to commercial production of fusaric acid to facilitate management of grapevine downy mildew disease. [ABSTRACT FROM AUTHOR]