Antifungal Activity of Verticillin D Isolated from Clonostachys rosea EC28 against Alternaria burnsii and Sclerotium rolfsii

Abstract

Alternaria leaf spot and white crown rot caused respectively by Alternaria sp and Sclerotium rolfsii are responsible for significant economic losses in tomato cultivation in Côte d'Ivoire. Chemical control of these diseases has its limits due to the harmful effects of synthetic fungicides on the environment and the health of farmers and populations. As a result, biological control through the use of biocontrol agents represents one of the alternative solutions. Clonostaschys rosea EC 28, a biocontrol agent is an endophyte fungus isolated from Ceiba pentandra, whose objective of this study was to show the antifungal properties of verticillin D produced by this fungus against A. burnsii and S. rolfsii. C. rosea EC 28 was cultured on rice medium and extracted with ethyl acetate. Open silica gel column chromatography of this crude extract led to the purification of two secondary metabolites that were identified by mass spectrometry and NMR as verticillin D and ergosterol. The activity in vitro antigerminative of A. burnsii spores and against growth mycelial growth of S. rolfsii of these molecules have been determined. Verticillin D inhibited A. burnsii spore germination and growth mycelial growth of S. rolfsii with respective MICs of 0.25 mg / mL and 5mg/ mL. Ergosterol n / A present none activity antifungal. These results provide a database for the use of Clonostachys rosea EC 28 as a potential biocontrol agent for two major tomato diseases in Ivory Coast.