The role of soil microbes in the plant adaptation to stresses: current scenario and future perspective

Environmental stresses hamper the growth and development of plants drastically, limiting their yield to considerable extent. Stresses alter normal metabolism and induce generation of toxic effects which ultimately downregulate growth and productivity. Environmental stresses hamper photosynthesis, mineral uptake and assimilation, and damage major cellular structures and their functioning. Soil microbes include a range of organisms that establish association with the plants and among the beneficial and more explored ones are arbuscular mycorrhizal fungi (AMF) and plant growth promoting rhizobacteria (PGPR). Both AMF and PGPR are believed to enhance plant growth by mediating several benefits to hosts. Mineral solubilization and availability, water content maintenance, modulation of root morphology and physiology, regulation of enzyme activity and sequestration of toxic ions, metals etc. are some of the key functions attributed to these beneficial microbes. The positive role of these microbes have been confirmed through molecular studies also. Their involvement in strengthening the tolerance mechanisms through upregulation of the antioxidant defense pathway, increased osmolyte accumulation, etc. have been well established. This chapter discusses the role of beneficial microbes, mainly AMF and PGPR, in improving the stress tolerance in plants focusing the relevant reports