Breeding Aims Elimination of Pollutants

Young poplars designed to extract heavy metals from soil.

Several biotech approaches have been taken to cleaning up pollution: Genetically modified microorganisms designed to break down organic pollutants Genetically modified microorganisms for detecting the presence and toxicity of particular pollutants Genetically modified plants designed to accumulate high levels of toxic metals

One example of this approach is the use of poplars with an enhanced ability to extract cadmium from contaminated soils. The toxic metal is taken up by the rapidly growing tree's roots, and is then stored in its wood and leaves for disposal.

Many plants are naturally capable of taking up small amounts of heavy metals. A gene from the bacterium Escherichia coli was transferred into poplars, which enables the transgenic trees to produce glutathione.

Glutathione is a phytochelatin, or a small peptide capable of binding to heavy metals, which makes them more mobile and helps mask their toxic effects. Transgenic plants expressing phytochelatins not only become able to take up much more toxin, they also become better suited to growing in heavily polluted soils.