Bioprospecting of native psychrotophic plant growth promoting bacteria induced chilling resistance in pea (Pisum sativum L.) by improving nutrient uptake and growth.

Agriculture in high-altitude regions is severely constrained by low temperatures, which limit crop productivity and microbial activity. In the present study, cold-tolerant plant-growth–promoting bacteria were isolated from high-altitude agro-ecosystems of Kinnaur and evaluated for their functional traits under low-temperature conditions. A total of 108 bacteria were isolated and subjected to in vitro characterization of cold stress tolerance. Further cold-adaptive bacterial isolates were also screened for PGP ability including solubilization of phosphorus (P), potassium (K), and zinc (Zn), N2-fixation, production of gibberellin, 1-aminocyclopropane-1-carboxylate (ACC), siderophores, ammonia (NH3), hydrogen cyanide (HCN), indole-3-acetic acid (IAA) and various extracellular hydrolytic enzymes. On the basis of screening, three efficient bacterial strains N2-fixer EU-PRN-28, P-solubilizer EU-PRN-61 and K-solubilizer EU-PRN-49 were molecularly identified as Rhizobium ruizarguesonis, Acinetobacter junii and Desemzia incerta, respectively. The identified strains were assessed for compatibility and evaluated as a single inoculum and in combination on pea under in vitro condition. Based on the results of the pot experiment, all the strains were further evaluated under in vivo condition. Results from a subsequent greenhouse and field experiment indicated that the formulation of a bacterial consortium distinctly increased pea shoot and root length, as well as fresh and dry biomass, chlorophyll, and phenolic and flavonoids content. To best of our knowledge, the present investigation is the first report on EU-PRN-28 R. ruizarguesonis, EU-PRN-61 A. junii, and EU-PRN-49 D. incerta associated with rhizospheric and root nodule region of pea from Kinnaur and also reported for the first time as a microbial consortium of these strains on the growth enhancement of pea. These findings highlight the potential of the developed bacterial consortium as a sustainable bioinoculant for enhancing crop performance under low-temperature and high-altitude agricultural conditions, with relevance for future field-level application.