Chapter 10 - Recent progress in enzymatic antioxidant defense system in plants against different environmental stresses

Abstract

Global warming and associated adverse environmental stresses greatly influence the normal functioning of plant growth and development and is a serious threat to modern agriculture throughout the world. Generally, there are two types of environmental stresses—biotic and abiotic—that affect plant growth and development. Abiotic stress such as water stress/drought, salinity, extreme temperatures, metal toxicity, etc. result in the loss of important crop plants, whereas biotic stress refers to damage caused by insects, herbivores, weeds, etc. Plants frequently encounter a variety of stresses, which lead to excess reactive oxygen species (ROS) production that hampers the structural and functional stability of the cell by inducing oxidative damage to lipids, proteins, and nucleic acids, which eventually result in reduced yield. Plants have developed a number of strategies to avert stress-induced oxidative damage, which includes the involvement of an antioxidant defense system consisting of numerous enzymatic and nonenzymatic antioxidant components. In this chapter, we focus only on the enzymatic antioxidant components of plants essential for coping with these challenges. The key regulatory enzymes of the antioxidant defense system includes superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), glutathione peroxidase (GPX), glutathione reductase (GR), glutathione S-transferases (GST), monodehydroascorbate reductase (MDHAR), and dehydroascorbate reductase (DHAR). These enzymes protect the plant cells under stressful conditions and maintain the cellular hemostasis by efficiently minimizing/scavenging the excess production of ROS molecules.