Arsenic Transport, Metabolism, and Possible Mitigation Strategies in Plants

Abstract

Arsenic (As) contaminated soil and groundwater lead to contamination of the food chain and poses serious risk to human health worldwide. Arsenic accumulation, particularly inorganic arsenic, in food crops leads to potential health problems including cancer in populations. Elucidation of the mechanisms for As transport and metabolism is a prerequisite to develop safer crops with reduced As levels and efficient phytoremediation methods. Arsenate is taken up by plants through the phosphate transporters, and arsenite and undissociated methylated As species through the nodulin 26-like intrinsic (NIP) and plasma membrane intrinsic (PIP) aquaporin channels. Arsenate is readily reduced to arsenite in planta, which is detoxified by complexation with thiol-rich peptides such as phytochelatins and/or vacuolar sequestration. Production of reactive oxygen species is induced by As exposure which can lead to the production of antioxidant metabolites and several enzymes involved in antioxidant defense. Nitrogen and sulfur assimilation pathways, oxidative carbon metabolism, amino acid and protein relationships are also affected by As exposure. Plant based remediation strategies either through natural or genetically modified plants for cleaning up of the As contaminated sites is a cost effective, green-clean technology that has been variously used for As containment. In the present chapter, the comprehensive knowledge generated in the area of arsenic transporters, its metabolism and phytoremediation from contaminated soil has been discussed.