An Endophytic Bacterial Approach: A Key Regulator of Drought Stress Tolerance in Plants

Drought is the chief limiting factor for crop productivity around the world. The continuous rise in temperature due to global climate change leads to scarcity of water which directly enhances drought frequency. One eco-friendly and safer approach is to utilize the endophytic bacteria as biofertilizers for agriculture productivity and sustainability. Plant-endophytic bacteria improve plant health through three types of interaction; they may be symbiotic, mutualistic and commensalistic. Endophytic bacteria have direct and indirect working mechanism for plant growth promotion. Direct mechanism involves making nutrient accessible to the plants via fixing nitrogen and solubilizing the phosphate, zinc and potassium, and siderophore, phytohormone and 1-aminocyclopropane-1-carboxylate (ACC) deaminase production, whereas indirect mechanism involves production of antibiotics, exopolysaccharide and hydrolytic enzymes and competition for nutrient and space to inhibit the pathogen. Thus, the aim of this chapter is to provide a better understanding of plant-endophytic bacterial interaction in amelioration of drought stress and determinants produced by endophytic bacteria beneficial in plant growth promotion under drought stress.