In vitro and in silico analysis of broad-spectrum bio-activity of essential oils derived from medicinal and aromatic plants against microbial phytopathogens

Phytopathogens are a major concern for crop production, affecting the global food demand. To address this issue, chemicals are widely employed that adversely affect the ecosystem. A sustainable alternative is essential to control phytopathogens for sustained crop productivity. Essential oils are potential alternative sources for efficient and sustainable management of phytopathogens. In this study the activity of six popular essential oils from medicinal plants, namely Cymbopogon flexuosus, Cymbopogon winterianus, Curcuma aromatica, Pogostemoncablin, Mentha arvensis and Cymbopogon martini, against the devastating pathogenic microbes Ralstonia solanaceaerum, Xanthomonas campestris, Magnaporthe oryzae and Bipolaris oryzae was tested.

Essential oils derived from C. winterianus and C. flexuosus were shown to be most effective at 5% concentration against the tested bacteria and fungus in vitro. Scanning electron microscopy analysis also revealed the effectiveness of C. winterianus and C. flexuosus essential oils against both microbial phytopathogens R. solanacearum and X. campestris. Further, the compounds found in these essential oils were identified by Gas Chromatography-Mass Spectroscopy and systematic in silico molecular docking analysis. The potential compounds responsible for the growth inhibition of microbial phytopathogens were bio-active compounds ( +)-aromadendrene, linalyl anthranilate and caryophyllene from C. flexuosus. Moreover, C. flexuosus showed high binding affinity towards bacterial, fungal, and insect target proteins. In a nutshell, the study revealed the potential of C. flexuous and C. winterianus as broad-spectrum biocontrol agents against major microbial plant pathogens.