Biochemistry of plant-microbe interactions in biofertilizer applications

The biochemical interplay between plants and soil microorganisms forms the cornerstone of sustainable agriculture through the application of biofertilizers. This review presents a comprehensive overview of the key biochemical mechanisms underpinning plant-microbe interactions, focusing on nutrient mobilization, metabolic integration, and stress alleviation. Biological nitrogen fixation, facilitated by nitrogenase enzymes in symbiotic and free-living diazotrophs, exemplifies how microbial processes supply essential nitrogen to plants under strict regulatory and oxygen-protective conditions. Similarly, phosphorus and potassium solubilization by microbial secretion of organic acids and enzymes such as phytases and phosphatases enhances the availability of otherwise inaccessible nutrients. Microbial production of plant growth regulators, including indole-3-acetic acid, gibberellins, and cytokinins, further stimulates root development and nutrient uptake. Iron acquisition via siderophores and modulation of stress responses through antioxidant enzyme stimulation and ACC deaminase activity are additional biochemical strategies that support plant growth under adverse conditions. The review also highlights the role of signaling molecules like flavonoids, Nod factors, and quorum sensing compounds, as well as root exudates, in establishing mutualistic networks that facilitate nutrient exchange and metabolic cooperation. Case studies in cereals, legumes, and vegetables demonstrate the practical applications of these biochemical interactions, confirming improvements in nutrient uptake, yield, and soil health. By synthesizing recent advances in molecular signaling, enzymatic activity, and nutrient cycling, this review underscores the potential of biofertilizers as eco-friendly solutions to enhance crop productivity and soil sustainability.