Regulation of Abiotic Stress by Salicylic Acid at Gene Level

Salicylic acid is a natural phenolic phytohormone detected in plants. It is involved in many aspects of development and survival in unfavorable conditions (phytopathogens, high temperature, cold stress, metallic stress, salinity, UV lights). It has been demonstrated that exogenous SA application ameliorates plant survival under abiotic stress via moderating stress effects and the alteration of the intracellular SA levels. In fact, it has been demonstrated that SA controls major plant-metabolic processes and the increase of SA concentrations in cells allows tolerance to abiotic stresses. Current studies have demonstrated that SA is important for controlling numerous physiognomies in plants at the gene level by stimulating a huge number of genes for synthetizing numerous proteins (like chaperones and heat shock proteins (HSPs)) and secondary metabolites. However, the basic molecular mechanisms that control the induction of SA under abiotic stresses remain unclear. In this chapter, we highlight the recent advances and understanding of the molecular mechanisms of SA-induced abiotic stress regulation. Thus, in this chapter, we aimed to (i) overview the biosynthesis of SA under optimal environments as well as under stressful conditions in plants and (ii) highlight major aspects of abiotic stress regulation by salicylic acid at gene level.