Enhanced secondary metabolite accumulation in tomato roots mediated by colonization of Paenibacillus dendritiformis confers crop protection against foot rot caused by Rhizoctonia solani

Abstract

Leveraging the dynamic and adaptable ecological environment of the plant rhizosphere, characterized by intense microbe-plant interactions, mediated by plant secondary metabolites, can sustain and enhance plant development. This study evaluates the potential of rhizosphere bacteria to protect tomatoes against foot-rot disease caused by Rhizoctonia solani (MTCC 12232). The optimal spore-forming soil bacterium, Paenibacillus dendritiformis (PD), isolated from the tomato rhizosphere, demonstrated significant antifungal activity, inhibiting fungal growth by 76.94 % and reducing fungal biomass by 83.69 %. Treatment with PD effectively controlled foot-rot disease, lowering its incidence to 16.2 %. Furthermore, bacterial treatments improved tomato plant root establishment, elongation, and phytohormone production, boosting seed germination to 87 %. The study shows that P. dendritiformis can trigger non-specific immune responses in colonized plants, resulting in higher levels of mycolytic glucanase and chitinase enzymes in infected roots, along with increased accumulation of peroxidase and polyphenol oxidase enzymes. These findings highlight the potential of P. dendritiformis as a viable biocontrol agent for environmentally friendly crop protection and production, with future studies aimed at field trials across diverse locations to validate and optimize its efficacy in various agricultural settings.