Role of phytohormones in stress tolerance of plants

Abstract

Environmental stresses, both biotic and abiotic, cause negative impact on plant growth and development, and plants need to adopt certain strategies for maintaining proper growth under stress conditions. These strategies include certain physiological, biochemical, and molecular mechanisms to cope with these stresses. These mechanisms include the production of hormones (phytohormones) and osmolytes. Phytohormones are organic molecules that affect various plant physiological processes like growth, development, and cell differentiation. Phytohormones regulate key physiological events under normal and stress conditions. They play a vital role for enhancing the ability of plants to adapt to the harsh environmental conditions by mediating a wide range of adaptive responses. These responses enable the plants to acclimatize to adverse soil conditions. Various types of phytohormones play an important function in plants individually or in coordination with each other. The nature and level of these hormones in plants are major factors that influence plant processes and functions. The present chapter describes the potential role of phytohormones for promoting plant growth and development under stress conditions. The major classes of plant hormones and their source of production have been described. Metabolism of phytohormones and their physiological responses with special reference to their concentration-dependent or negative impact on plant growth have been discussed in detail. The impact of these hormones on plant growth under stress conditions has been reviewed and discussed with selected examples. Also, the role of microbes in phytohormone production has been elaborated with examples. Future perspectives of the area have also been discussed.