ANTIOXIDANT DEFENCE SYSTEM AND ITS STRESS FACTORS IN PLANTS

Abstract

In normal oxygen activity metabolism, reactive oxygen species originate as a natural by-product. Apoplasts,
chloroplasts, mitochondria, and peroxisomes are the main sites of the production of reactive oxygen species in
the cell..Enzymatic antioxidants like catalase, superoxide dismutase, ascorbate peroxidase, glutathione
reductase, general peroxidases, monodehydroascorbate reductase as well as dehydroascorbate reductase and
non-enzymatic antioxidants such as ascorbic acid, alpha-tocopherol, glutathione elimination, carotenoids,
ubiquinone/plastoquinone and flavonoids; Both metabolite and enzyme classes collaborate to scavenge reactive
oxygen species, but also to analyze plant signaling, immunological response, growth, and development.