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) and stressed (N 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.gFw), chlorophyll b (0.2-0.4 mg.gFw), and carotenoid (12-13 mg.gFw), whereas low electrolyte leakage and lipid peroxidation, and high membrane stability were observed in the treated plants. Interestingly, low proline content (20-21 μg.gFw) and total soluble sugar (0.2 mg.gFw) were observed in the treated plants. In contrast, a higher total amino acid content (1.0 mg.gFw) was estimated in the treated plants. Enhanced antioxidant and scavenging activities of treated plants were observed compared to untreated plants under N 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.