Reversing gene foils virus.

Viruses cause diseases by invading the cells of susceptible plants and hijacking the cell reproductive mechanism. They take over the cell functions designed to replicate plant DNA and convert it to production of new virus particles.

According to University of Missouri-Columbia biochemist June Bourque, many of the most serious plant diseases are caused by viruses, but traditional control methods don't always work. "Pesticides control insects that spread viruses. But more emphasis is now placed on breeding resistant crop varieties, because we are more aware of the potential harmful effects of insecticides on the environment. Breeding crop plants for disease resistance has had limited success. Often, appropriate genes have not been found in the crop or a closely related species. Therefore, traditional plant breeding techniques of crossing and selection won't work."

Bourque aims to induce plant resistance to viruses by isolating a small, but essential, fragment of viral RNA, rearranging it so that it interferes with expression of the virus gene and incorporating it into the plant DNA. RNA and DNA are two forms of nucleic...