Arsenic Stress in Plants

Being a toxic metalloid and group I carcinogen, Arsenic (As) poses a threat to plants, especially to crops which are consumed by human beings, and sooner or later results in hyper/hypopigmentation and skin cancer. It is a well‐known fact that South‐East Asia is suffering from groundwater As contamination, and according to a recent report, the contamination has been found also in Hungary, Mexico, Argentina, Australia, United States, etc. Thus, As contamination has become a global problem. As is toxic even at low concentration because it has no known function as nutrients. Arsenite (III) and arsenate (V) are the main phytoavailable forms of inorganic arsenic. Being analogous to phosphate, As(V) is transported by a phosphate‐cotransport system in plants, whereas As(III) is transported through ‘ OsNIP2.1 ’ (member of aquaporin superfamily) in rice. Besides, ‘ AsSe1’ (As‐accumulation gene), ‘ AsTol’ (As‐tolerance gene) and ‘ OsACR2.1’ (an arsenate reductase gene) have also been identified. The production of phytochelatins (PCs), a metal‐binding thiol peptide, in response to As stress may hold a way of proper As tolerance in plants but still needs a thorough study. However, with the proper knowledge of arsenic speciation, transportation, accumulation, overexpression in crop plants may result in ways to develop arsenic tolerant transgenics.