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Role of salicylic acid in inducing salinity tolerance in plants
Salinity caused an increase in Na+ concentration and a decrease in concentration of N, P, K+, Ca2+, Mg2+ and other nutrients in both shoots and roots. The high concentrations of Na+ negatively affected the intracellular K+ accumulation, presumably either by competing for influx sites, or affecting membrane stability and causing leakage of K+. Recent progress in molecular genetics and plant electrophysiology suggests the plant capacity to maintain a high cytosolic K+/Na+ ratio may be critical to salt tolerance. Salicylic acid (SA) is a phytohormone, and also an important signal molecule for mediating plant defence against a range of environmental stresses. Though SA is involved in inducing resistance against several biotic and abiotic stresses, mode of action of SA against salinity stress remains unclear. In particular, effects of SA on Na+, Ca2+, and Cl- uptake and K+ homeostasis need to be elucidated.
Abiotic stress is the principal cause of crop failure worldwide, resulting in severe yield reduction in most major crops. Among abiotic stresses, salinity is a major one, affecting 7% of the world’s total land area and causing billion dollar losses in crop production worldwide. These saline lands could be managed either by introducing salinity-tolerant cultivars or by inducing salinity tolerance through exogenous addition of compatible solutes to meet the ever growing food demand. Under field conditions, salinity always induces other stresses like artificial drought, oxidative stress, etc... Hence, exogenous addition of compatible solutes seems to be the easier option to manage multiple stresses. Thus, salicylic acid has received particular attention because of its involvement in plant defence against biotic and abiotic stresses.