Phenotypic analysis of Arabidopsis mutants: heavy metal stress

INTRODUCTIONArsenic (As) is a major environmental contaminant, arising from both industrial and agricultural use, and is one of the metals given top priority for remediation by the U.S. Department of Energy on the basis of its toxicity and widespread contamination. However, many of the molecular and genetic mechanisms contributing to arsenic toxicity and detoxification remain unknown in plants. The toxicity of arsenic depends on the arsenic oxidation state. The main arsenic oxidation states are As(III) and As(V), both of which are highly toxic to plants and animals. In plants, As(III) disrupts the sulfhydryl groups of proteins and induces the production of hydrogen peroxide, which leads to membrane damage, whereas As(V) uncouples phosphorylation in mitochondria and at high levels can inhibit seed germination. As described in this protocol, resistance or sensitivity to arsenic can be easily scored by measuring germination and root bending in exposed seedlings.