Microbial inoculation in drought challenged rice triggered multipronged steps at enzymatic, non-enzymatic and gene expression level. These multifarious modulations in plants were related to stress tolerance mechanisms. Drought suppressed growth of rice plants but inoculation withTrichoderma,Pseudomonasand their combination minimized the impact of watering regime. InducedPALgene expression and enzyme activity due to microbial inoculation led to increased accumulation of polyphenolics in plants. Enhanced antioxidant concentration of polyphenolics from microbe inoculated and drought challenged plants showed substantially high values of DPPH, ABTS, Fe-ion reducing power and Fe-ion chelation activity, which established the role of polyphenolic extract as free radical scavengers. Activation of superoxide dismutase that catalyzes superoxide (O₂⁻) and leads to the accumulation of H₂O₂was linked with the hypersensitive cell death response in leaves. Microbial inoculation in plants enhanced activity of peroxidase, ascorbate peroxidase, glutathione peroxidase and glutathione reductase enzymes. This has further contributed in reducing ROS burden in plants. Genes of key metabolic pathways including phenylpropanoid (PAL), superoxide dismutation (SODs), H₂O₂peroxidation (APX,PO) and oxidative defense response (CAT) were over-expressed due to microbial inoculation. Enhanced expression ofOSPiPlinked to less-water permeability, drought-adaptation geneDHNand dehydration related stress inducibleDREBgene in rice inoculated with microbial inoculants after drought challenge was also reported. The impact ofPseudomonason gene expression was consistently remained the most prominent. These findings suggested that microbial inoculation directly caused over-expression of genes linked with defense processes in plants challenged with drought stress. Enhanced enzymatic and non-enzymatic antioxidant reactions that helped in minimizing antioxidative load, were the repercussions of enhanced gene expression in microbe inoculated plants. These mechanisms contributed strongly towards stress mitigation. The study demonstrated that microbial inoculants were successful in improving intrinsic biochemical and molecular capabilities of rice plants under stress. Results encouraged us to advocate that the practice of growing plants with microbial inoculants may find strategic place in raising crops under abiotic stressed environments.

Agricultural chemicals either used as nutrient inputs for soil fertility or pesticides are creating physicochemical and biological deterioration of the soils and disturbing the agro-ecosystems worldwide. Alarming concerns towards integrated agroecology demand for renewed interest in low-external input-based farming practices. These practices comprise strengthening of soil biological properties, recycling of inherent soil minerals and reuse of agricultural residual wastes.