news @ nature.com - Transgenic mustard sucks up selenium - First field results prove plant can remove soil contaminants.:
Farmland in certain parts of California is heavily irrigated, and the water dissolves selenium in shale found in the region. As the water evaporates on the surface soil, selenium is concentrated to levels that are toxic to plants. But Indian mustard (Brassica juncea) has a natural resistance to the element, and absorbs it as it takes in water through its roots.
"Indian mustard is able to grow fast and attain a high biomass even under environmentally stressful conditions," says Norman Terry, a plant biologist at the University of California, Berkeley, who led the study. The researchers boosted Indian mustard's abilities by adding extra genes that produce selenium-hungry enzymes.
The natural resistance and sequestration of selenium is an evolutionary adaptation to challenging environments. Scientists used that as a starting point to make the mustard more effective. They knew which genes to look at because of the naturally evolved adaptations. Evolutionary hypotheses generate new theories, which rehabilitate polluted farmland.