Adaptive physiological responses of plants under abiotic stresses: Role of phytohormones

Abstract

Abiotic stress factors such as drought, flooding, cold, heat waves, ultra violet radiations, oxidizing agents and salinity in the current era of climate change is jeopardizing the plant growth and development leading to crop failure worldwide. Engineered plants with improved tolerance to abiotic stresses would provide oppor- tunities to adapt crops to future climates coupled with enhanced food productivity and sustainable agricultural development. Growth and development of plants involve a wide range of sophisticated genetic, hormonal, metabolic and environmental events which are tightly regulated by internal and external cues, such as phytohor- mones (including various biostimulants and different organic and inorganic elici- tors), temperature, light irradiation, etc. Out of these, phytohormones such as jasmonates, gibberellins, abscisic acid, brassinosteroids, nitric oxide, salicylic acid, etc. have evolved to control vital functions in regulating various plant physiological and developmental processes, ranging from seed germination, photosynthesis, leaf senescence, pollen growth, to plant defense responses, and ameliorating various abiotic stresses. The role of such phytohormones in conferring plant adaptation under dynamic climate changes is still in infancy stage. Few reports are available on the current topic. In this chapter, we attempt to summarize recent studies that have provided insights of the plant environmental adaptability and the multidimensional role of different phytohormones viz. salicylic acid (SA), nitric oxide (NO) and hydrogen sulphite (H2S) in regulating various developmental processes and stress tolerance, taken together with the molecular mechanisms of phytohormone signalling.