Reactive Oxygen Species and Antioxidants in Plants: An Overview

Plants exposed to biotic and abiotic stresses generate more reactive oxygen species (ROS) than their capacity to scavenge them. Biological molecules are susceptible to attack by ROS, including several proteins, polyunsaturated fatty acids and nucleic acids. The cellular arsenal for scavenging ROS and toxic organic radicals include ascorbate, glutathione, tocopherol, carotenoids, polyphenols, alkaloids and other compounds. Enzymatic antioxidants including superoxide dismutase, peroxidase, catalase and glutathione reductase detoxify either by quenching toxic compounds or regenerating antioxidants involving reducing power. Various aspects relating to sensors for ROS and signaling role of ROS in plants, improvement of antioxidant systems in transgenic plants and functional genomics approaches used to unravel the reactive oxygen gene network has been discussed.