Mechanisms of Chromium Tolerance, Uptake and Accumulation in Plants: A Hazardous Substance in the Food Chain
Anthropogenic activities have caused progressive environmental pollution and degradation. In particular, metal contamination has dramatically increased since the industrial revolution, causing severe damages to water sources and soil. To overcome these environmental hazards, phytoremediation is suggested as a sustainable approach for environmental rehabilitation, which aims at using plants to remove heavy metals from contaminated soil or water through their uptake by roots and transfer to the above-ground parts. However, the molecular and cellular mechanisms involved in transition metal uptake and accumulation are still not completely clear. Assessment of the possible role of sulfate transporters in chromium uptake and accumulation: results show evidence for chromate - sulfate competition, together with enhanced tolerance to chromium when root-localized high-affinity sulfate transporters are genetically silenced, and hypersensitivity when they were over-expressed in genetically transformed plants. Sulfate transporters are suggested to play an important role in chromium uptake from the soil environment into plant cells, and detrimental chromium effects may be caused by competition with sulfate at low chromium concentrations and by chromium toxicity at higher concentrations.
Keywords- Chromium, Heavy metals, Metal toxicity, Plant sulfur transport,