Coping with Drought: Consequences, Responses, and Plant Growth Promoting Rhizobacteria Mediated Amelioration Mechanisms in Crop Plants

Drought stress is one of the most ruthless environmental factors restricting crop yield efficiency as most crop plants are susceptible to drought stress. Due to the global climatic variations, the environmental conditions are deteriorating continuously. As a result, a wide range of transformation and stress relief strategies are needed to adapt to such a stressful situation. Since long ago, breeding of drought-tolerant plants for developing drought-resistant crops and other physical methods like regulated deficit irrigation (RDI), partial root-zone drying (PRD), etc., have also been attempted to overcome drought stress. Nonetheless, such conventional and physical techniques are time-consuming and cost escalated; there is a need to fill out some simple and low-cost strategies and utilize a momentary premise for drought stress management. Recently, potential PGPR boosting growth and productivity of plants under drought stress has been explored. PGPR confer drought tolerance by producing phytohormones, exopolysaccharides, 1‑aminocyclopropane-1-carboxylate deaminase, osmolytes, volatile compounds, regulation of antioxidant system and stress-responsive gene expressions, and alteration in root system architecture that help plants adapt to dry conditions. Thus, drought tolerant-PGPR can be an efficient tool for a sustainable agroecosystem. In this review, the effects and responses in plants under drought stress are discussed. Apart from this, particular emphasis is given to discuss the PGPR-mediated mechanisms of drought amelioration and tolerance responses in crop plants with a future research perspective.