Transport and detoxification of metalloids in plants in relation to plant-metalloid tolerance

Abstract

Metalloids are key environmental contaminants and when present in high concentrations in soil, adversely affect crop productivity. Plants possess several transporters that maintain required level of essential metal ions inside the cells so as to perform different metabolic activities. Transporters are responsible for the entry and distribution of different elements inside various cells and organs of the plant. Many toxic metalloid ions share the transport network of essential ions due to their similar structural properties like phosphate transporters, aquaglyceroporins, hexose transporters, sulphate transporters, etc. Presence of excess amounts of toxic metalloid ions inside the plant tissues causes severe damages to cell biomolecules, affects key metabolic processes, inhibits growth of plants ultimately leading to decreased crop yield. Therefore detoxification strategies of metalloids at the tissue level are essential in order to minimize their toxic effects. Employing mutants, attempts have been made by various groups of workers to restrict the uptake of many pollutant metalloids by plants by reducing the activities of transporters and to overexpress metalloid binding peptides and proteins such as phytochelatins, metallothioneins for sequestration of metalloids in the tissues. Reduced transport of metalloids in the tissues coupled with their increased sequestration inside the cells would lead to generation of metalloid-tolerant crop plants. The present review summarizes our current status of knowledge in this direction related to transport mechanisms and detoxification strategies of metalloids in crop plants in relation to Plant-Metalloid tolerance.