ABSTRACT
Department of Agricultural and Food Engineering, Indian Institute of Technology Kharagpur, Kharagpur-721302, India, Fax: 91-3222-255303, E-mail: sdg@agfe.iitkgp.ernet.in
Free radicals have an important role in the developmental and metabolic processes of aerobic organisms. The amount of ROS generated by various metabolic processes could be increased by environmental stimuli in the form of various stresses. Production of ROS can cause cellular damage directly or indirectly through the formation of secondary toxic substances (Benson 1990, 2000). Uncontrolled production of free radicals occurs when antioxidant protection systems become saturated, for example, due to stress, aging, pathological disease or due to physical damage. To protect themselves against such oxidative damage, plants developed a complex array of antioxidant system (Larson 1988). Antioxidant protection system includes enzymes like superoxide dismutase (SOD), catalase (CAT) and peroxidase (POX) as well as low molecular substrates like ascorbate (AA), glutathione (GSH) and α-tocopherol, which scavange both radicals and their associated non-radical oxygen species. The balance between the production of ROS and quenching activity of antioxidants is upset when plants are exposed to environmental stress.
