Antifungal activity of wild bergamot (Monarda fistulosa) essential oil against postharvest fungal pathogens of banana fruits

Abstract

This study aimed to examine the antifungal activity of wild bergamot (Monarda fistulosa) essential oil on Colletotrichum musae and Lasiodiplodia theobromae, the causative organisms of anthracnose and crown-rot diseases of banana fruits, respectively. Chitin synthase is a promising target for antifungal compounds, since it is involved in synthesizing chitin, which forms a major proportion of the fungal cell wall. Disc volatilisation method was employed to assess the in vitro antifungal activity of the oil. The vapours of this essential oil at 4 μL per Petriplate exhibited 100% growth inhibition of both the fungal pathogens, and at 66.66 μLL−1 , it significantly (P <0.05) reduced the incidence and severity of anthracnose and crown-rot diseases in artificially wounded and infected fruits. The chemical composition of wild bergamot essential oil was determined by GC-MS technique and the components of the essential oil were docked against chitin synthase to determine the components responsible for antifungal activity. Chitin synthase was modelled by de novo approach due to non-availability of the 3D structure. The in silico techniques such as molecular docking and conceptual DFT revealed that the major components of the essential oil namely thymol, carvacrol and cinnamyl carbanilate manifested the best antifungal activity. This illustrates effective inhibition of the major postharvest diseases of banana by wild bergamot essential oil.