Genetic engineers had hoped to revolutionize agriculture by creating crops that fight off insects and disease. But the most common strategy, slipping in genes that cause the plants to make a natural pesticide, is turning out to be flawed. The problem: Insects quickly develop resistance to the pesticide. So researchers at North Carolina State University in Raleigh have come up with an ingenious scheme against one common pest -- tiny worms called nematodes, which damage up to $100 billion a year of such crops as potatoes, soybeans, and tobacco.
According to researchers, when the worms burrow into the roots to feed, they trigger a genetic change in the plants. Some root cells become greatly enlarged, serving as giant feeding sites. Normally, each worm lives for about 25 to 30 days, during which the females lay hundreds of eggs. NCSU's Mark A. Conkling and Charles H. Opperman decided to attack the feeding sites by inserting into the plant a genetic package containing a cell-killing gene. This is attached to a genetic switch that turns on only when a worm enters the cell. Once the feeding cells are dead, the worm quickly starves to death. This same strategy, Conkling says, may also work against many plant viruses and fungi.