An introduction to reactive oxygen species metabolism under changing climate in plants

Plants are subjected to various kinds of abiotic stresses throughout their life cycles which include salinity, drought, temperature (heat and cold), heavy metal, nutrient deficiency and UV radiation. Such types of stresses in plants lead the overproduction of certain chemical entities known as reactive oxygen species (ROS) which are highly reactive and cause damage to proteins, lipids, carbohydrates and macromolecules. The ROS include hydrogen peroxide (H²O₂), superoxide radical (O₂•^-), hydroxyl radical (OH^•), perhydroxyl radical (HO₂ ^•), etc. But, nature has gifted the plants with very efficient enzymatic (superoxide dismutase, SOD; catalase, CAT; ascorbate peroxidase, APX; glutathione reductase, GR; monodehydroascorbate reductase, MDHAR; dehydroascorbate reductase, DHAR; glutathione peroxidase, GPX; guaiacol peroxidase, GOPX; and glutathione-S-transferase, GST) and non-enzymatic (ascorbic acid, AA; glutathione, GSH; tocopherols; flavonoids; proline; etc.) antioxidant defence systems which work in coordination to detoxify and protect plant cells from oxidative damage. Moreover, ROS play a role as secondary messenger which induces cell to undergo programmed cell death.