Salicylic Acid-Mediated Salt Stress Tolerance in Plants

Abstract

Salt stress is one of the most important abiotic stresses threatening agricultural production worldwide. Salt stress affects vital physiological, biochemical and molecular processes in crop plants, leading to reduced plant growth and yields or even plant death. To cope with salt stress, plants have evolved many adaptive mechanisms, including the development of salt-associated signal transduction cascades that contain a wide range of second messengers. During stress, regulatory molecules, including plant hormones, play key roles in controlling developmental processes and signalling networks, and these molecules have been recognized as having the potential to be used to develop stress-tolerant plants. Salicylic acid (SA) is a phenolic compound involved in the regulation of plant growth, development and defence responses. SA is a critical signalling molecule that is known to participate in the responses of plants to salinity stress, through extensive signalling crosstalk with other hormones that results in physiological and biochemical responses in plants and changes in gene expression. SA is an important regulator of Na+ exclusion and sequestration, through the modulation of sodium and potassium transporters, and is associated with the control of photosynthesis and nutrient metabolism, proline and glycinebetaine synthesis, reactive oxygen species metabolism, and plant–water relations, in plants under salt stress. Furthermore, applying SA has been shown to improve plant tolerance to salinity by regulating multiple stress-responsive pathways and processes. Recent studies with transgenic and mutant plants have shown the diverse roles SA in plant stress biology. This chapter summarizes the current knowledge of the roles of SA in salinity tolerance, the responses of plants to salt, and the potential mechanisms underlying SA-mediated salinity tolerance in plants.