Plant growth-promoting rhizobacteria (PGPR) play a vital role in alleviating biotic and abiotic stresses in plants. They enable plant growth under adverse circumstances and help improving the yield through several direct or indirect mechanisms. With the aid of PGPR, plant can fix atmospheric nitrogen, produce phytohormones, enhance water and nutrient uptake, solubilize phosphate, and improve the provision of binding iron with the help of siderophores. PGPR-induced indirect mechanisms help plant to suppress parasitism by some deleterious rhizobacteria through induced systemic resistance, antibiosis, competition for nutrients, and production of metabolites. Thus, application of PGPR is a sustainable approach to reduce the use of chemical fertilizers in crop field. Bio-fertilizers containing PGPR have great economic prospect and potential for environmental benefits. This review highlights the various roles of PGPR in promoting growth and development of plant in a stressful environment. The study also encompasses the successful application of PGPR strains for nitrogen fixation, management of nutrients, water and salt stresses, controlling plant insects, and phytopathogens. Furthermore, recent know-how on the underlying mechanisms of PGPR-induced systemic resistance in plants will be helpful to investigate their additional uses.
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