2012•Unpublished venueRequires access
Generation and Scavenging of Reactive Oxygen Species in Plants under Stress
Sarvajeet Singh Gill, Lamabam Peter Singh, Ritu Gill, Narendra Tuteja
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Abstract
Reactive oxygen species (ROS) such as singlet oxygen (1O2), superoxide radicals (O2•−), hydrogen peroxide (H2O2), hydroxyl radicals (OH•), and perhydroxyl radicals (HO2•−) are constantly produced as by-products of various metabolic processes in plants and continuously reduced/scavenged by plant antioxidative defense system to maintain at a certain steady-state levels. Any disruption in this delicate balance between ROS generation and reduction/scavenging leads to high accumulation in plant cells, which causes oxidative stress. Plants counteract ROS toxicity through enzymatic antioxidant systems comprising a range of ROS scavengers, such as superoxide dismutase (SOD), ascorbate peroxidase (APX), glutathione peroxidase (GPX), catalase (CAT), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), guaiacol peroxidase (GPOX), glutathione reductase (GR), and glutathione S-transferase (GST), and nonenzymatic low molecular metabolites, such as ascorbic acid (ASH), glutathione (GSH), α-tocopherol, proline, carotenoids, and flavonoids. Various biotic and abiotic stresses such as plant diseases, drought, salinity, extreme temperatures, excess light, pollutants, nutrient deficiency, and so on disturb the equilibrium of ROS production and scavenging, eventually leading to overproduction and higher accumulation of ROS. High amount of ROS in plant cells affects various cellular functions through damaging nucleic acids, protein oxidation, and lipid peroxidation, eventually resulting in cell death. ROS toxicity resulted from various biotic and abiotic stress factors is considered to be one of the major causes of low crop productivity worldwide. Despite this, it has also become clear that ROS play an important signaling role in plants, controlling various processes such as cellular growth, control of stomata closing, plant–harmful/beneficial microbe interactions, programmed cell death, and stress responses, and can also initiate responses such as new gene expression.