Plant Responses to Exogenous Salicylic and Jasmonic Acids Under Drought Stress

In a vast area of the farming lands in the world, drought stress is an important factor for limiting plant growth and productivity. Adjusting hormonal signaling of plants under drought stress is one of the main goals of plant physiologist to increase drought stress tolerance and productivity of plants. Salicylic (SA) and jasmonic acids (JA) are involved in plant defense mechanism against abiotic stress tolerance such as drought. These growth regulators considerably enhance antioxidative capacity (enzymatic and non-enzymatic) of plant cells, which largely reduce lipid peroxidation and maintain membrane integrity. Exogenous salicylic and jasmonic acids increase plant osmolytes such as proline and soluble carbohydrates in response to drought stress. The critical roles of these growth regulators in enhancing photosynthetic activities under drought stress have been confirmed. Moreover, salicylic and jasmonic acids can change the biosynthesis of secondary metabolites in drought subjected plants. In this chapter, the SA and JA mechanisms of actions in changing physiological and biochemical properties of plants favoring drought tolerance were discussed.