ABSTRACT
Stress is an inevitable challenge plant come across; either abiotic or biotic or both. Environmental stress causes adverse effects on plant growth and development and leads to negative effect on agriculture like lower crop yield and poor quality. Plant reacts to the stress by producing excess reactive oxygen species (ROS), which causes oxidative stress that affects the plant’s own cells. Various cell organelles produce different kinds of ROS with different characteristic features. A limited quantity of ROS is required to the plant for its normal biochemical, physiological activities and is maintained by antioxidant defense systems (non-enzymatic and enzymatic antioxidants). Antioxidant components are plant secondary metabolites, play a role in defense mechanisms. Equilibrium between the ROS generation and its detoxification is much required to the plant system in order to survive under adverse environmental stresses. Hence, the field of research in this area has attracted researchers massively. A large area of research needs to be addressed/remains unexplored in understanding the ROS action as a signaling molecule. In this chapter, generation of ROS, types of ROS, site 220of ROS generation, response of ROS to different environmental stresses, ROS as signaling molecule and detoxification of ROS by antioxidants are highlighted and have been discussed in detail.
