Multifunctional Pseudomonas putida strain FBKV2 from arid rhizosphere soil and its growth promotional effects on maize under drought stress

In the present study, rhizobacteria were isolated from the rhizosphere of maize, okra, eggplant, tomato, green gram, peanut and red gram grown in arid and semi-arid regions in India and were screened for drought tolerance in Trypticase soy broth (TSB) supplemented with different concentrations of polyethylene glycol 6000 (PEG 6000). Out of 23 isolates, three could tolerate minimal negative water potential of −1.03 MPa and were evaluated for plant growth promoting (PGP) traits under control and drought stress (−1.03 MPa) conditions. Pseudomonas spp. strain FBKV2 isolated from eggplant (Solanum melongeana L.) rhizosphere, showed multiple PGP traits under both control and drought stress conditions. The strain was identified as Pseudomonas putida by 16S rRNA sequence analysis and the sequence was submitted to GenBank under the accession number KT311002.1. The strain was evaluated for growth promotion of maize (Zea mays L.) under drought stress. Seedlings inoculated with P. putida strain FBKV2 showed better growth in terms of shoot, root length, and dry biomass. Furthermore, inoculation improved cellular metabolites and stomatal conductance in maize seedlings. Scanning electron microscopy confirmed the colonization of P. putida strain FBKV2 on the root surface of maize seedlings. The present study demonstrates that the isolation of indigenous drought tolerant P. putida strain FBKV2 from stressed ecosystems can be a very useful approach for the development of bio-inoculants for drought stress management in crops.