Frontiers in Azotobacter-mediated plant development and stress mitigation: proteomic, nanobiotechnology, and genomic insights

Globally, microbe-assisted, sustainable crop resilience solutions are required because abiotic stresses caused by climate change, high salt, temperature extremes, heavy metal toxicity, and drought drastically lower agricultural productivity and soil health. Because of their numerous roles in biological nitrogen fixation, phytohormone synthesis, antioxidant regulation, and stress reduction, Azotobacter species have emerged as significant phytobiome members among plant growth-promoting rhizobacteria (PGPR). Despite extensive agronomic evidence, a fragmented understanding persists regarding the molecular, proteomic, genomic, and nanobiotechnological mechanisms that govern Azotobacter-mediated plant stress tolerance, as well as limitations in inoculant stability and field efficacy under variable environmental conditions. This review critically summarizes recent advances in Azotobacter-mediated plant development and stress alleviation, focusing on stress-resilient species includes Azotobacter chroococcum, Azotobacter salinestris, Azotobacter vinelandii, and Azotobacterpaspali. It highlights key molecular pathways and nitrogen genes related to nitrogen fixation and stress regulation, including nifHDK, vnfHDGK, anfHDGK, and accD, as well as the modulation of ethylene, antioxidant enzyme activity, osmolyte accumulation, and phytohormonal signaling. Omics-driven insights, particularly genomics and proteomics, are discussed to elucidate stress-responsive proteins, alternative nitrogenase systems (Mo-, V-, and Fe-only nitrogenases), and post-translational modifications underlying plant–microbe interactions. Furthermore, the integration of nanobiotechnology is explored as a revolutionary approach to enhance Azotobacter performance, emphasizing the role of nanoparticles such as ZnO, Fe₃O₄, SiO₂, Cu-based nanoparticles, nano-encapsulation matrices, and nanosensors in improving microbial delivery, stability, stress detection, and nutrient use efficiency. By integrating multi-omics perspectives with nano-enabled bioformulations, this review provides a comprehensive framework positioning Azotobacter as a next-generation bioinoculant for climate-resilient, sustainable agriculture and highlights future directions for developing robust, field-applicable microbial technologies.