Interaction of the novel bacterium Brachybacterium saurashtrense JG06 with Arachis hypogaea leads to changes in physio-biochemical activity of plants to cope with nitrogen starvation conditions

Plant-microbe interactions are widely accepted, steady, and native methods used against different environmental stress conditions. In this study, peanut plants grown under control (with N-2) and stressed (N-2 deficit) conditions with or without the bacterium Brachybacterium saurashtrense were assessed for different physio-biochemical activities and differential gene expression. Higher shoot (24-25 cm) and root length (12-15 cm), and fresh (7-9 g) and dry weight (1-1.5 g) were observed in the treated plants compared to untreated plants under stress conditions. Similarly, high total chlorophyll (0.5-0.7 mg.g(-1)Fw), chlorophyll b (0.2-0.4 mg.g(-1)Fw), and carotenoid (12-13 mg.g(-1)Fw), whereas low electrolyte leakage and lipid peroxidation, and high membrane stability were observed in the treated plants. Interestingly, low proline content (20-21 mu g.g(-1)Fw) and total soluble sugar (0.2 mg.g(-1)Fw) were observed in the treated plants. In contrast, a higher total amino acid content (1.0 mg.g(-1)Fw) was estimated in the treated plants. Enhanced antioxidant and scavenging activities of treated plants were observed compared to untreated plants under N-2 stress conditions. A total of 263 genes were differentially expressed; the majority (93%) of which belonged to unknown/uncharacterized/hypothetical categories, followed by metabolism (1.8%) and photosynthesis (1.3%) in the treated peanut plants. Overall, the diazotrophic plant growth promoting novel bacterium B. saurashtrense JG06 provides endurance to peanut plants by modulating physio-biochemical activity and host-gene expression under nitrogen starvation conditions. Plant metabolites, including flavonoids and phenolics, also play a protective role in abiotic stress by scavenging free radicles. This study provides new insight into plant-microbe interactions in the host plant.