ABSTRACT
This chapter proposes that whether reactive oxygen species (ROS) act as signal transducing or damaging molecules is mainly dependent on their quality and second, on their quantity. As ROS play multifunctional roles, it is essential for cells to control the level of ROS strictly to avoid any injury caused by oxidative stress without removing them completely. During abiotic stresses, ROS are produced due to the disruption of various metabolic pathways, such as respiration and photosynthesis, and as part of the abiotic stress-response signal transduction network in plants. The chapter focuses on abiotic stress–induced ROS production, oxidative damage caused by ROS, and the role of the antioxidative defense system in plants growing under different abiotic stresses. Lipid peroxidation is regarded as the primary molecular mechanism associated with cellular oxidative damage. ROS attack on proteins causes site-specific modification of amino acids, peptide chain fragmentation, aggregation of cross-linked reaction products, modified electric charge, and enhanced susceptibility of proteins to proteolysis.
