Genetic engineering of transgenic tobacco for enhanced uptake and bioaccumulation of mercury.

To further enhance the efficiency and potential of plants for phytoremediation of mercury pollution, a genetically engineered tobacco to simultaneously express mercury transporter, mercury transporter (MerT) and mercury chelator, polyphosphate (polyP) was constructed by integrating bacterial merT gene in polyphosphate kinase gene (ppk)-transgenic tobacco, and its ability to phytoremediate mercury was evaluated. Integration of merT gene into ppk-transgenic tobacco did not significantly affect the mercury resistant phenotypes and polyP production. Transgenic expression of MerT in ppk-transgenic tobacco resulted in accelerated and enhanced mercury uptake into tobacco. In addition, tobacco expressing MerT and polyP accumulated significantly more mercury than the ppk-transgenic tobacco from medium containing a wide range of low concentrations of Hg(2+). The combination of accelerated mercury uptake and enhanced mercury accumulation mediated by MerT represents one way for shortening the purification completion time, and for improving tobacco plants to be more suitable for use in phytoremediation of low levels of mercury contamination.