Silencing Pests: Altered Plants Make RNA That Keeps Insects at Bay

Article excerpt

Two teams of researchers have modified plants to produce genetic material that disables critical genes in insects that eat the plants. The technique could provide a new strategy for agricultural-pest control.

Looking for a new way to protect corn plants, James Roberts with Monsanto in Chesterfield, Mo., and his colleagues turned to a mechanism known as RNA interference, in which segments of the genetic molecule RNA block the translation of information from a target gene (SN: 7/2/05, p. 7). The researchers found RNA sequences that would target critical genes in the western corn rootworm and two other related pests, and then modified corn so that it would generate those sequences.

In rootworms that fed on the modified corn, RNA from the plants shut down the target gene, stunting or killing the insects'

larvae, the researchers report. Modified corn plants infested with corn-rootworm eggs suffered less root damage than did normal corn.

In the other study, Xiao-Ya Chen and his colleagues at the Chinese Academy of Sciences in Shanghai used a similar trick to increase the cotton bollworm's sensitivity to gossypol, a defense chemical produced by the cotton plant.

Although large doses of gossypol stunt the growth of bollworm caterpillars, the pests can tolerate the chemical at low concentrations. Chen and his colleagues found the insect gene responsible for this tolerance, and then modified Arabidopsis, a widely used lab plant, to produce silencing RNA for that gene. Insects that feasted on the modified lab plants ingested the RNA, and stopped growing when fed gossypol. The researchers are trying to reproduce their results with cotton plants. …