Rhizobacterial-mediated tolerance to plants upon abiotic stresses

Abiotic stresses, as an intense environmental restriction, gradually constrain agricultural productivity. Developing strategies for tolerance against abiotic stresses may help improve crop productivity. The utilization of microorganisms is an emerging science branch that represents the potential of microbes in facilitating plants' struggle toward abiotic stresses. Improved tolerance of crops via plant breeding or genetic manipulation is a prolonged process. Hence, the application of plant growth-promoting rhizobacteria (PGPR) brings forward an alternative manner that may confer resilience in plants exposure to abiotic stresses. The utilized mechanism of PGPR-induced stress tolerates the regulation of genes and proteins expression in various metabolisms followed by the enhancement of antioxidant capacity, the increment in amino acids, soluble sugars, and choline acclimation as osmolytes, the improvement of soil structure, stability, and water potential via exopolysaccharides accumulation, the alteration of root architecture on account of increased gibberellin, indole-3-acetic acid, and cytokinin, the reduction of ethylene content by the ACC deaminase, and ultimately the utilization of signaling hormones and volatile compounds to activate induced systemic tolerance in plant. In the present chapter, we elaborate on the role of PGPR in assisting plants in coping with abiotic stresses.