Enhancement of Plant Tolerance to Oxidative Stress Injury by Exogenous Application of Hydrogen Peroxide: A Review

Abstract

Under oxidative stress, there are excess production of reactive oxygen species (ROS) e.g Singlet oxygen (O•
2), Super oxide (O‾ 2), Hydrogen peroxide (H2O2) and Hydroxyl radical (OH‾). These reactive radicals almostly damage all cell components such as membrane lipids, photosynthetic pigments and chloroplasts, enzymes and nucleic acids. In spite of H2O2 is a strong oxidizing agent under stresses, its high levels damage plant photosynthesis and cause poorly developed plants and initiate programmed cell death. In contrast, H2O2 at low concentration is considered as a stress signal, keeping reactive oxygen species under control, limiting endogenous H2O2 concentration to enhance plant tolerance under stress. At low concentration acts also as a promotor and a key regulator in a broad range of physiological and biochemical processes in plants under various stresses. H2O2 at low concentration would enhance the production of enzymatic activity e.g super oxide dismutase (SOD), catalase (CAT), guaiacole
peroxidase (POD), ascorbate peroxidase (APX), glutathione reductase (GR)) and non enzymatic antioxidants e.g carotenoids, ascorbic acid (ASA), glutathione (GSH), α-tocopherol (Vit E), proline, total phenols, soluble sugars and some minerals) which cause marked decrease in the oxidative damage represented by lipid peroxidation (MDA) and electrolyte leakage of plant cells to finally improve
growth, yield and fruit quality.