Biotic Stress Alleviation in Plant Using Rhizobacteria: An Overview of Mechanism of Action, Antimicrobial Compounds Production, (Nano) Formulations and Employment Methods.

The biotic stress induced by phytopathogens causes a significant loss to several crops in terms of yield and quality. Biotic stress may disrupt phenotypic characteristics and alter metabolic pathways in plants. Sustainable approaches like the employment of rhizobacteria control phytopathogens and diseases thereof through production of antimicrobial compounds and boosting plant defense systems. Rhizobacteria protect plants through mechanisms such as competition for food and niche to pathogens, production of antibiotics, induced systemic resistance and stimulation of antioxidant enzymes in plants helping them to mitigate pathogen-induced oxidative stress. This review concisely presents ample studies on the role of rhizobacteria in controlling phytopathogens including their mechanism of action, pathogenesis responsive metabolic pathways and regulatory genes. There are commercially available biocontrol agents for a variety of crops and more need to be developed based on host specificity and agro climatic conditions. This review further highlights the approaches for rhizobacterial formulation development and employment methods followed by future prospects to reduce the dependence on agrochemicals to ensure food security and quality using an eco-friendly sustainable approach. Encapsulated formulation of bacteria with nanomaterial is an innovative technological approach for enhanced efficacy and controlled delivery of active chemicals leading to suppression of plant disease severity more effectively versus bare bacteria to achieve improved plant health and food security.