Essential oils work synergistically to mitigate pathogenic impact of Meloidogyne incognita, Rhizoctonia solani and Sclerotinia rolfsii

Abstract

The phytochemical analysis and potential synergistic interactions between the essential oils (EOs) of Vitex negundo L. Piper longum L. and Vitex agnus-castus L. and their pesticidal efficacy were the main focus of this study. To examine their synergistic interactions with pesticidal activities, the recovered EOs were mixed in binary and ternary combinations at similar ratios and the nematicidal activity of individual EOs and their mixtures was evaluated. Using the disc-diffusion method, antifungal activity was evaluated. For comparison means of biological activities, a two-way ANOVA was carried out, at a significance level of 5% (p<0.05). The main EO compounds were subjected to a molecular docking investigation to look into how they interacted with target proteins in comparison with standard inhibitors physostigmine (AChE), ethacrynic acid (GST-1), and hexaconazole (CYP51). The chemical compounds of EOs were identified via GC-MS analysis. Based on GC-MS analysis β-pinene, cis-nerolidol, 2-heptyl acetate, and α-pinene were the major compounds identified in PLAO; while in VACAO viridiflorol, β-caryophyllene, and 5-(1-isopropenyl-4,5-dimethyl bicyclo[4.3.0]nonan-5-yl)-3-methyl-2-pentenol acetate were detected as main components. Similarly, 1,8-cineole, (E)-β-ocimene, α-terpinyl acetate, and (Z)-β-ocimene were identified as major compounds in VACAO. When three EOs of P. longum, V. negundo, and V. agnus-castus were mixed, pesticidal activity results revealed a high synergy. These results validate synergistic interactions amongst the studied essential oils, which may support sustainable agriculture when applied as natural products against pathogens. The molecular docking results showed good binding affinities and attributed the strongest inhibitory activity to 5-(1-isopropenyl-4,5-dimethyl bicyclo[4.3.0]nonan-5-yl)-3-methyl-2-pentenol acetate for all the target proteins.