Rhizobacterial Strategies for Abiotic Stress Mitigation: From Molecular Mechanisms to Precision Microbiome Management

Abstract

Global food security faces continuous pressure from abiotic stresses induced from climate change, for instance, drought, salinity, heat, and waterlogging. Therefore, crop productivity is suppressed, and agricultural systems become vulnerable worldwide. Plant growth-promoting rhizobacteria (PGPR) are biological agents that can mitigate these effects through molecularly diverse mechanisms, including biological nitrogen fixation, phosphate solubilization, phytohormone biosynthesis, ACC deaminase-mediated ethylene modulation, induction of systemic resistance, antioxidant enzyme upregulation, and osmoregulatory adaptation. This review critically synthesizes PGPR-mediated stress tolerance and evaluates microbiome engineering as tools for enhancing rhizosphere functionality under stressed climate. Beyond their well-known role as biofertilizers, PGPR can act as an intelligent biological component, which is integrable within digital farming frameworks. Introduction of PGPR within major cropping systems, including rice, wheat, maize, legumes, and horticultural crops, are assessed alongside synergistic combinations with biochar, nanoparticles, and organic amendments. Major barriers, namely inconsistent field performance, instable formulation, regulatory constraints, and limited data infrastructure in developing countries are critically examined. Future research priorities include AI-guided microbiome engineering, CRISPR-based strain optimization, and integration of PGPR within circular bioeconomy models. This review establishes a comprehensive framework for adopting PGPR within next-generation, digitally enabled, climate-resilient agricultural systems.