Pollution of the environment is one of the major problems facing the modern world. Removal of toxic metals poses particularly difficult problems, as unlike organic pollutants they cannot be biodegraded. Currently the standard way of removal of toxic metals from contaminated areas is by excavation and subsequent burial of the soil at a hazardous waste site. Phytoremediation -- the rapidly developing technique of using plants to extract metals from soil - presents a much preferred alternative.
Application of natural plants for phytoremediation is limited and not very effective. Genetically engineered plants, which can be designed to be metal-specific, present unlimited possibilities for removal of toxic metals from soils and water.
Dartmouth researchers in collaboration with their colleagues at the University of Minnesota have identified the IRT1 (iron-regulated transporter) gene encoding a probable Fe(II) transporter. IRT1 is predicted to be an integral membrane protein with a metal-binding domain. The gene was cloned from Arabidopsis thaliana, a common weed in the mustard family, by functional expression in a yeast strain defective for iron uptake. In Arabidopsis, IRT1 is expressed in roots and is induced within 24 hours after transfer of plants to iron deficient growth conditions. Data base comparisons and Southern blot analysis indicated that IRT1 is a member of a gene family in Arabidopsis.
Related sequences were also found in the genomes of rice, yeast, nematodes, and humans. The novel transporter appears to draw the metal cadmium into cells as well. The specificity of IRT1 induction is being tested with plants starved for various metals. Identification of the IRT gene family has also allowed Dartmouth scientists to isolate several Arabidopsis genes which functional studies in yeast suggest may encode zinc transporters. These findings suggest that the newly discovered class of genes may be involved in controlling the uptake of several metals by cells.
Dartmouth scientists have already obtained the seeds from transgenic Arabidopsis plants engineered to over express the IRT1 gene and are preparing a series of experiments with these genetically engineered plants to monitor their ability to extract various metals from contaminated soil and liquid solutions.
This technology is claimed in the issued United States Patent Nos. 5,846,821, 6,162,900, and 6,590,140. We are seeking an industrial partner to further refine and market this technology. (Ref: J5)
Last Updated: 7/24/12