Novel Insights into the Role of Microbes on Seedling Emergence and Vigour under Abiotic Stress for Climate Resilient Agriculture

Abstract Plant growth-promoting microorganisms (PGPR) inoculated with seeds represent an innovative method in sustainable agriculture, and for improving crop performance in various environmental conditions. Microbial seed treatment promotes better germination, improve nutrient availability, stronger seedlings, water-use efficiency, stimulate root growth architecture and enhanced plant health, thus decreasing dependence on traditional chemical inputs. It modulates phytohormones including auxin, cytokinins, and abscisic acid, which support better plant development under stress. Environmental conditions including salinity, water deficit, metal toxicity stress, and other abiotic stresses, along with desiccation and temperature variations, pose considerable challenges, as they can greatly undermine microbial integrity and functionality. Microbial seed coating under water-deficit condition triggers stress-responsive gene expression, including dehydrins and aquaporins, which assist in maintaining cellular balance and improve stress adaptation. The intricate biochemical and physical processes, including exopolysaccharide production enhances rhizosheath stability, the activity of ACC-deaminase for regulating ethylene, and the induction of antioxidant defense systems for the detoxification of reactive oxygen species (ROS) support seedlings in overcoming challenging conditions. Beneficial microbes modulate plant signaling pathways including MAPK pathways, abscisic acid and dehydration‑response/antioxidant genes inducing systemic tolerance that integrates osmotic adjustment, hormonal tuning, and defense activation. Emerging research should focus on developing climate-resilient, multi-strain microbial seed treatments with enhanced shelf life and field performance under diverse abiotic stress conditions.