Virtual screening and in vitro analysis to understand the inhibitory effect of alliin on pythium splendens- pathogen of root rot disease

The oomycete Pythium splendens, is a plant pathogen causing significant damage to broad spectrum of commercially and medicinally valuable plants such as black pepper, tomato, watermelon, bean etc. These pathogens are known to affect almost all parts of the plant by secreting effector proteins, prominent for their virulence. The most common method in practice to control these infections is usage of chemical fungicides but with severe toxicity. As an alternate, biofungicides such as crude extracts of plants is also widely used. In the present study, we aim to provide molecular evidence for the inhibitory activity of plant extracts from Azadirachtaindica, Allium sativum and Curcuma longa against P. splendens through molecular docking and invitro studies. Molecular docking analysis revealed that Alliin in Allium sativum showed significant molecular interactions with P. splendens necrosis and ethylene-inducing peptide 1 (Nep1)-like proteins compared to commercially available chemical fungicides. The inhibitory potential of the lead compound was experimentally validated through Minimum Inhibitory Concentration (MIC) assay which was in good agreement with the insilico prediction. Thus, this study confirms the antifungal property of the natural lead compounds and the plant extracts to effectively combat against Pythium infections.