Genetic engineering to enhance mercury phytoremediation

Most phytoremediation studies utilize merA or merB genes to modify plants via the nuclear or chloroplast genome, expressing organomercurial lyase and/or mercuric ion reductase in the cytoplasm, endoplasmic reticulum or within plastids. Several plant species including Arabidopsis, tobacco, poplar, rice, Eastern cottonwood, peanut, salt marsh grass and Chlorella have been transformed with these genes. Transgenic plants grew exceedingly well in soil contaminated with organic (similar to 400 mu M PMA) or inorganic mercury (similar to 500 mu M HgCl2), accumulating Hg in roots surpassing the concentration in soil (similar to 2000 mu g/g). However, none of these plants were tested in the field to demonstrate real potential of this approach. Availability of metal transporters, translocators, chelators; and the ability to express membrane proteins could-further enhance mercury phytoremediation capabilities.