Heavy Metal Tolerance in Arabidopsis thaliana

Understanding of molecular mechanisms of heavy metal (HM) tolerance is an important issue in plant biology because HM contamination has become a potential risk for modern agriculture. HMs generally cause toxicity to plants at very low amounts, while several HMs are essential elements that are involved in various biological processes. It means that plants have developed tolerant mechanisms that can protect cells from HM cytotoxicity. This system consisted of various steps such as uptake, translocation and sequestration to particular organelles, which are regulated by transporters, and the cytosolic detoxification by binding to the metal-binding molecules such as phytochelatins. Molecular biological mechanisms of these complex systems have been identified in Arabidopsis thaliana and its relative HM hyperaccumulator species Arabidopsis halleri. Many of critical genes for HM tolerance were identified from either forward genetics with sensitive mutant and by quantitative loci analysis or reverse genetics using knockout mutants available at the worldwide resource centers. In addition, new approaches such as transcriptomics have contributed uncovering the complex system of plant HM tolerance.