Plant growth-promoting rhizobacteria-alleviators of abiotic stresses in soil: A review

With the continuous increase in human population, there is widespread usage of chemical fertilizers that are responsible for introducing abiotic stresses in agricultural crop lands. Abiotic stresses are major constraints for crop yield and global food security and therefore require an immediate response. The implementation of plant growth-promoting rhizobacteria (PGPR) into the agricultural production system can be a profitable alternative because of its efficiency in plant growth regulation and abiotic stress management. These bacteria have the potential to promote plant growth and to aid in the management of plant diseases and abiotic stresses in the soil through production of bacterial phytohormones and associated metabolites as well as through significant root morphological changes. These changes result in improved plant-water relations and nutritional status in plants and stimulate plants'' defensive mechanisms to overcome unfavorable environmental conditions. Here, we describe the significance of plant-microbe interactions, highlighting the role of PGPR, bacterial phytohormones, and bacterial metabolites in relieving abiotic environmental stress in soil. Further research is necessary to gather in-depth knowledge on PGPR-associated mechanisms and plant-microbe interactions in order to pave a way for field-scale application of beneficial rhizobacteria, with the aim of building a healthy and sustainable agricultural system. Therefore, this review aims to emphasize the role of PGPR in growth promotion and management of abiotic soil stress with the goal of developing an eco-friendly and cost-effective strategy for future agricultural sustainability.