Arsenic induced oxidative stress in plants

Arsenic is a highly toxic metalloid for all forms of life including plants. Arsenic enters in the plants through phosphate transporters as a phosphate analogue or through aquaglycoporins. Uptake of arsenic in plant tissues adversely affects the plant metabolism and leads to various physiological and structural disorders. Photosynthetic apparatus, cell division machinery, energy production, and redox status are the major section of plant system that are badly affected by As (V). Similarly As (III) can react with thiol (-SH) groups of enzymes and inhibits various metabolic processes. Arsenic is also known to induce oxidative stress directly by generating reactive oxygen species (ROS) during conversion of its valence forms or indirectly by inactivating antioxidant molecules through binding with their -SH groups. As-mediated oxidative stress causes cellular, molecular and physiological disturbances in various plant species. Activation of enzymatic antioxidants namely, superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT) and glutathione reductase (GR), Glutathione s-transferase, glutathione peroxidase (GPX) as well as non antioxidant compounds such as, ascorbate, glutathione, carotenoids are reported to neutralize arsenic mediated oxidative stress. Understanding of biochemistry of arsenic toxicity would be beneficial for the development of arsenic tolerant crops and other economically important plants.