The use of transgenic plants in the bioremediation of soils contaminated with trace elements

The use of plants to clean-up soils contaminated with trace elements could provide a cheap and sustainable technology for bioremediation. Field trials suggested that the rate of contaminant removal using conventional plants a nd growth conditions is insufficient. The introduction of novel traits into high biomass plants in a transgenic approach is a promising strategy for t he development of effective phytoremediation technologies. This has been ex emplified by generating plants able to convert organic and ionic forms of m ercury into the less toxic, volatile, elemental mercury, a trait that occur s naturally only in some bacteria and not at all in plants. The engineering of a phytoremediator plant requires the optimization of a number of proces ses, including trace element mobilization in the soil, uptake into the root , detoxification and allocation within the plant. A number of transgenic pl ants have been generated in an attempt to modify the tolerance, uptake or h omeostasis of trace elements. The phenotypes of these plants provide import ant insights for the improvement of engineering strategies. A better unders tanding, both of micronutrient acquisition and homeostasis, and of the gene tic, biochemical and physiological basis of metal hyperaccumulation in plan ts, will be of key importance for the success of phytoremediation.