Oxidative Stress

Plants are exposed to various biotic and environmental stresses under a natural environment that trigger the reactive oxygen species (ROS). These ROS are produced during plant metabolism in different cellular compartments (mitochondria, chloroplast, peroxisomes, plasma membrane NADPH oxidases, etc.) and have a dual function. Higher production and accumulation of ROS lead to oxidative stress, causing injury to cell organelles and vital biomolecules. However, in normal growth conditions, ROS act as signaling molecules and regulate several processes related to plant growth and development, including cell division, germination, reproductive development, and hormonal regulation. The role of ROS in stress-related responses has been well established. Among different ROS, the hydrogen peroxide (H2O2), hydroxyl ions (OH¨), superoxide anions (O2 ¨), and singlet oxygen (1O2) are more important. These ROS are produced at specific cellular compartments and vary in their reactivity. H2O2 is relatively stable ROS and acts as a strong signaling molecule during biotic and abiotic stresses. In this chapter, the production and metabolism of different ROS, their toxicity, and a scavenging mechanism in plants have been discussed. The role of ROS in the regulation of plant growth and development and effect of abiotic stress on ROS production has also been described.