Physiological role of nitric oxide in plants grown under adverse environmental conditions

Abstract

Plant production in the recent times is facing various kinds of abiotic stress which are considered as major factors limiting crop productivity worldwide. Radical global climatic and other environmental changes have forced the need for a better understanding of plant stress responses and tolerance, particularly in the light of increasing intense stressors like salinity, drought, flooding, toxic metals, temperature extremes, high-light intensity, UV-radiation, herbicides, ozone, among others. Over the past decade, the understanding of plant adaptation to environmental stress, including both constitutive and inducible determinants, has grown considerably. Exploring suitable crop improvements or ways to alleviate stress is one of the tasks of plant biologists. Research on nitric oxide (NO) in plants has gained considerable attention in recent years mainly due to its function in plant growth and development and as a key signaling molecule in different intracellular processes. The role of NO in stress responses in plants has been increasingly focused in plant science over the last decade. NO is an essential signaling molecule with multiple physiological and biochemical functions involving the induction of different intracellular processes, including the expression of defense-related and redox-regulated genes in the detoxification of abiotic and biotic stress-induced reactive oxygen species (ROS). Although significant progress has been made in understanding NO biosynthesis and signaling in plants, several crucial questions remain unanswered. In this chapter, we review recent progress in NO research in a broader context of abiotic stress tolerance and discuss its diverse roles in physiological and biochemical processes in plants and the protective mechanisms it exhibits towards abiotic stress tolerance.