Insights in the Physiological, Biochemical and Molecular Basis of Salt Stress Tolerance in Plants

Abstract

Salt stress is one of the most brutal abiotic stresses that arrests crop survival and productivity. It affects various physiological, biochemical and metabolic processes in plants, depending on severity and duration of the stress. Plant adaptation or tolerance to salinity stress involves complex physiological traits, metabolic pathways, and molecular or gene networks. In response to high salinity stress, various genes get upregulated, the products of which are involved either directly or indirectly in plant protection. Some of the genes encoding osmolytes, ion channels, receptors, components of calcium signaling and some other regulatory signaling factors or enzymes are able to confer salinity tolerance, when transferred to sensitive plants. Overall, the susceptibility or tolerance to high salinity stress in plants is a coordinated action of multiple stress-responsive genes. Plants that grow under different soil conditions are usually inhabited by microbes which are beneficial for the enhancement of their salinity tolerance mechanisms. Microbes, either independently or by interacting with plants, synthesize some organic osmolytes and other substances which offer an adaptive strategy to salinity stress. The partnership of plants with nitrogen-fixing bacteria and arbuscular mycorrhizal fungi can serve as a second possible and sustainable strategy to increase crop yields in saline soil. A comprehensive understanding on how plants respond to salinity stress at different levels and an integrated approach of combining molecular tools with physiological and biochemical techniques are inevitable for the development of salt-tolerant varieties of plants in salt affected areas.