Environmental fluctuation leads to overproduction of ROS, which are extremely toxic and damages cellular biomolecules i.e. nucleic acid, DNA, lipid, and protein. However, the delicate balance between ROS production and antioxidant machinery of the plant is always maintained under normal condition but during stress, this balance comes to a halt. To ensure the plant survival under stressful environment, plants have adopted well equiped antioxidant defense machinery having two forms: (i) Enzymatic such as Superoxide Dismutase (SOD), Ascorbate Peroxidase (APX), Catalase (CAT), Dehydroascorbate Reductase (DHAR), Monodehydroascorbate Reductase (MDHAR), Glutathione Reductase (GR) and Guaiacol Peroxidase (GPX); and (ii) Non-enzymatic such as reduced glutathione (GSH), Ascorbic Acid (AA), Carotenoids, α-tocopherol, proline and flavonoids. In this review, a summarized form of ROS action and their regulation via antioxidant machinery of plant cells have been discussed.

Keywords: Antioxidants, Oxidative stress, Reactive Oxygen speices, Redox status.