Comparing the growth-promoting potential of Paenibacillus lentimorbus and Bacillus amyloliquefaciens in Oryza sativa L. var. Sarju-52 under suboptimal nutrient conditions

An adequate supply of mineral nutrients is crucial to obtain optimum productivity in agriculture. The present investigation was carried to find the inoculation effect of plant growth-promoting rhizobacteria (PGPR), i.e., Paenibacillus lentimorbus B-30488 (B-30488), Bacillus amyloliquefaciens SN13 (SN13) and their consortium for the growth of rice var. Sarju-52, grown under suboptimal nutrient conditions. The study revealed that the individual PGPR treatments showed comparatively better performance than consortia in morphological, physiological, biochemical, and nutrient analysis. Towards understanding the complex mechanism(s), untargeted metabolite profiling was performed using GC-MS, showed alteration of metabolites in rice seedlings facing suboptimal nutrient conditions and inoculated with PGPR. Metabolites such as oleic acid, mannitol, and ethyl iso-allocol were accumulated significantly under starved conditions. Under suboptimal nutrient conditions, sugars such as ribose, glucose, fructose, trehalose, palmitic acid, and myristic acid were accumulated significantly in PGPR inoculated seedlings. The significantly altered pathways due to PGPR inoculation under suboptimal nutrient conditions mainly belongs to carbohydrate and fatty acid metabolism. Interestingly, it was observed that among all the treatments, inoculation with SN13 performed comparatively better than other treatments. Further, in SN13 inoculated samples the qRT-PCR analysis of transcription factors and metabolism-related genes were validated that indicates PGPR deploy metabolic re-programming in rice var. Sarju-52 to enhance its nutrient use efficiency, tolerance, and growth under suboptimum nutrient conditions.