Harnessing Plant Microbiomes to Modulate Molecular Signaling and Regulatory Networks in Drought Stress Adaptation.

Drought stress is a major abiotic factor limiting global crop productivity by disrupting cellular homeostasis, impairing photosynthesis, and restricting metabolic activity. Plant-associated microorganisms, including rhizobacteria, endophytes, and arbuscular mycorrhizal fungi, play key roles in enhancing drought resilience through molecular, biochemical, and physiological mechanisms. These beneficial microbes modulate phytohormone biosynthesis, enhance osmolyte accumulation, increase organic acid exudation, and activate ROS-scavenging antioxidant pathways. Microbe-mediated regulation of aquaporins, heat shock proteins, and root system architecture further improves water-use efficiency, hydraulic conductance, and stress acclimation. Advances in microbial genomics and systems biology have revealed the molecular drivers of plant-microbe synergism, enabling the development of tailored microbial consortia and next-generation bioinoculants. Complementarily, genetic and genome-guided modulation of drought-responsive regulatory hubs including transcription factors (e.g., DREBs, NACs, MYBs, and bZIPs), signal transducers (e.g., MAPKs and CDPKs), and protective proteins enhances adaptive plasticity under water deficit conditions. This review integrates current molecular insights into drought-induced perturbations in plants and highlights the convergence of microbial interventions and genome-guided strategies in reinforcing drought tolerance. Emphasizing mechanistic frameworks, scalable microbial technologies, and molecular breeding approaches, this work underscores their potential to improve crop resilience in increasingly water-limited environments.