Arsenic Toxicity and Molecular Mechanism of Arsenic Tolerance in Different Members of Brassicaceae

Abstract

Arsenic (As) is a predominant contaminant in soil and water in many regions of the world, including China, India and Bangladesh. The metalloid is capable of accumulating to toxic levels in many plants, including crops, and can severely reduce the yield and quality of the same. Arsenic is a potent carcinogen, and causes severe and chronic toxicity in humans (arsenicosis), making the contamination of soil and plants with As an additional source of concern. Certain plants are able to tolerate high levels of metalloid without showing symptoms of toxicity. A further specialized variety of heavy metal–tolerant plants are the hyperaccumulators, which can accumulate high levels of the toxicant endogenously, without compromising its own growth. Brassica is an important genus of oil crops belonging to the family Brassicaceae that is cultivated worldwide. Several members of this family show significant potential in accumulating As from contaminated soil. Various mechanisms of As transport, metabolism and tolerance in plants are presented; and the potential of utilization of Brassica in phytoremediation of As-contaminated soil has been discussed. A brief outline of the different tolerance pathways exhibited by Brassica at the molecular level deciphered to date is also highlighted in detail. Further studies into the molecular mechanisms of tolerance and accumulation in Brassica may offer an economically productive mode of phytoremediation of As-contaminated soil utilizing different species of Brassica.