Arsenite in plant biology: How plants tackle it?

Among toxic elements, arsenic (As) comes under group 1 carcinogenic metalloid. Its presence in the soil and irrigation water in a higher concentration than permissible limit has become a threat to crop production and human livelihood. Crop plants, specifically those used as staple foods, exhibit the highest As accumulation which subsequently accumulates in the human body after their consumption, leading to severe fatal diseases. As occurs in two main inorganic forms including trivalent (As(III)) and pentavalent (As(V)), of which the trivalent form is more toxic. In plants, uptake of As(III) is affected by oxidizing or reducing environment of the soil and the pH and is mediated by various transporters such as Nodulin-26-like aquaporins (such as Lsi1 and Lsi2). Plants utilize various strategies that help them to withstand the toxic effect of As(III) including reshuffling in many biochemical and physiological processes. These strategies include the use of endogenously generated or exogenously applied chemicals or plant growth regulators. This review article discusses the uptake, transport, and various mechanisms to tolerate higher As(III) in plants. Besides, an update on the use of protectants in curtailing As(III) toxicity in crop plants has also been described.