Drought is one of the major constraints on agricultural productivity worldwide and is likely to increase even further with global warming. Several adaptations and mitigation strategies are required for plants to survive in drought. Beneficial soil microbes, for example plant growth promoting rhizobacteria (PGPR) and arbuscular mycorrhizal fungi (AMF), may alleviate drought stress with different mechanisms. PGPR affect the plant by improving nutrient acquisition, modulating the level of plant hormones, such as auxins, cytokinins and ethylene, inducing accumulation of osmolytes and antioxidants. With the production of extracellular polymeric substances (EPS) they may improve soil structure and water retention properties, thus enabling the plant to survive in drought conditions. AMF help maintain water potential of the plant and protect the plant from oxidative stress. Furthermore they improve water acquisition and soil structure.Various studies have documented the increased health and productivity of different plant species by the application of beneficial microbes under both normal and stressed conditions. Beneficial soil microbes therefore possess potential for modulating the physiological response to water deprivation, which may ensure plant survival under drought stress.
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