Submitted to: Environmental Science and Technology
Publication Type: Other
Publication Acceptance Date: 7/14/2005
Publication Date: 3/1/2005
Citation: Banuelos, G.S., Terry, N., Leduc, D., Ellon-Smits, E., Mackey, B.E. 2005. Field trial of transgenic Indian mustard plants shows enhanced phytoremediation of selenium contaminated sediment. Environmental Science and Technology. 39:1771-1777. Interpretive Summary: The use of phytoemediation as a technology for the cleanup of selenium and other trace elements is currently limited by the slow rate of the biological processes involved. There is a need to develop plants that can remove toxic trace elements from soil at much faster rates than are presently available. Genetic engineering offers an exciting and inovative approach for increasing the efficiency of phytoremediation. In this regard, three different transgenic lines of Indian mustard were created for accumulating more selenium than an untransformed line of Indian mustard. The four lines of Indian mustard were tested under field conditions for their ability to accumulate selenium from drainage sediment applied to a field site. All three transgenic lines accumulated and volatilized more selenium than the untransformed Indian mustard after 6 weeks of growth in the field. These results are significant because this is the first scientific report showing that plants genetically engineered for phytoremediation can perform successfully under field conditions.Conducting this field trial with transgenic plants has given us a unique opportunity to test transgenic plants under "real-life" conditions.
Technical Abstract: Three transgenic Indian mustard (Brassica juncea) lines were tested under field conditions for their ability to remove selenium (Se) by extraction and volatilization from Se- and boron-contaminated saline sediment. The three transgenic lines overexpressed genes encoding the enzymes adenosine triphosphate sulfurylase (APS), y-glutamyl-cysteine synthetase (ECS), and glutathionl synthetase (GS), respectively. The APS, ECS, and GS transgenic plants accumulated 3.7-, 2.4-, and 2.1-fold more Se in their leaves than the untransformed wild type Indian mustard, respectively. The GS plants tolerated the contaminated sediment best, and attained an above ground biomass/area almost 80 percent of that of GS plants grown on clean soil. Measurements of Se volatilization showed that trangenic plants volatilized more Se (up to 27% with GS plants) than the untransformed wild type plants. This is the first report showing that Indian mustard plants genetically engineered for Se phytoremediation can perform successfully under field conditions.