Microbial Synergy for Zinc and Iron Biofortification: Enhancing Crop Nutrition Through Plant-Microbe Interactions

Zinc (Zn) and iron (Fe) are essential micronutrients crucial for numerous physiological and metabolic functions in plants and humans. Their prevalent deficiencies in soils is a pervasive question escort to abridged crop productivity and throw in notably to malnutrition, on global scale, principally in mounting regions where staple crops form the bulk of the diet. To address the dietary micronutrient deficiencies, a range of interventions has been implemented, with biofortification standing out as a sustainable and economically viable long-term solution. Biofortification may be accomplished via agronomic, conventional breeding, transgenic, and, more recently, microbe-assisted modalities. This review delineates the pivotal role of plant growth-promoting microorganisms (PGPMs)—integral agents in biogeochemical nutrient cycling—in augmenting the accumulation of zinc and iron in crop plants. These microbes mediate nutrient acquisition through a intricate mechanisms, including the biosynthesis of organic acids, phytohormones, and siderophores; upregulation of metal transporter gene expression; morphological and anatomical modulation of root architecture; and enhancement of nutrient bioavailability via the solubilization of zinc, phosphorus, and potassium. Furthermore, microbial attributes such as nitrogen fixation, exopolysaccharide (EPS) secretion, biofilm formation, and antagonistic activity against phytopathogens collectively strengthen plant health and facilitate micronutrient assimilation. Elucidating and strategically exploiting these multifaceted microbial functionalities lead to the development of environmentally benign and sustainable biofortification paradigms and advance global food and nutritional security.