Abstract
Multiple plant growth-promoting attributes with N-acyl homoserine lactone (AHL)-mediated quorum sensing exhibiting bacterial strains can help plants to withstand varying abiotic and biotic stress conditions for improving the plant health and productivity. In total, 306 bacterial isolates were isolated from diverse locations and sites. In our exploration, bacterial isolates were screened based on AHL production, plant growth-promoting attributes, abiotic stress tolerance, and antagonistic activity against phytopathogenic fungi. Among the screened 306 isolates, 4 (11VPKHP4, 7VP51.8, P51.10, NBRI N7) were selected based on their efficiency in AHL production, biofilm formation, enduring different abiotic stress conditions, exhibiting plant growth-promoting attributes, and antagonistic activity. Based on 16S rRNA gene sequencing analyses of the selected 4 isolates belong to Pseudomonas genera. Selected isolates 11VPKHP4, 7VP51.8, P51.10, and NBRI N7 were also proficient in biosurfactant production, emulsification, suggesting that all isolates fabricate emulsifiers. The plant growth promotion potential of selected 4 bacterial isolates showed significant growth enhancement in all the vegetative parameters of Zea mays under control as well as drought stress condition. Biochemical parameters and defense enzymes under drought stress conditions were also modulated in the PGPR treated plants as compared to their uninoculated respective controls. With quorum sensing, multiple PGPR attributes, stress tolerance, biofilm formation, and EPS production the selected isolates have the potential to facilitate enhanced plant growth, rhizosphere colonization, maintenance of soil moisture content under normal and diverse stresses.
Highlights
All living beings on this planet are affected by varying climatic conditions such as prolonged drought, intense rains, flooding, high and low temperatures that exert a detrimental impact on plants as well as on soil microbes too
Producers with A136; coupling of the traR gene with lacZ provides a basis for the detection of acyl-homoserine lactones based on β-galactosidase activity (Fig. 1 and 2) whereas, none of the isolates were found to be positive with CV026
Intensive research has been done towards characterizing the bacterial isolates from different locations for the presence of PGP attributes and their efficiency for enhancing plant growth under abiotic stresses.[48,49]
Summary
All living beings on this planet are affected by varying climatic conditions such as prolonged drought, intense rains, flooding, high and low temperatures that exert a detrimental impact on plants as well as on soil microbes too. Many approaches are being used to cope up with this critical condition and among them, researchers are focusing on agro-eco-friendly sustainable technology by exploitation of plant growth-promoting rhizobacteria (PGPR) based formulations for improving stress amelioration, soil fertility, and crop productivity
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