AND NOW a human gene can be environmental groups call it a "landfound in plants. A Canadian scientist mark decision". has succeeded in adding a human The problem in the affected areas gene - metallothionein - to plants has been caused by excessive use of like rapeseed, tobacco and alfalfa. fertilisers, which take up to 40 years Scientists are now trying to engineer to percolate to underground water the plants to express the gene in non- supplies. edible parts. Plants bearing metallothionein, which produces a protein that attracts metals, will be used to clean up polluted water and soil in mining areas. In another project, scientists have also engineered a cholera gene into alfalfa and are trying to make a food-based cholera vaccine from the engineered plant.