RESEARCH AIM: PLANTS THAT WILL MAKE OWN INSECTICIDES

COLUMBIA -- University of Missouri-Columbia scientists are trying to genetically engineer plants that can manufacture their own insecticides.

"If the research is successful, farmers could minimize their use of insecticides, which would be better for the environment and would reduce the farmers' production costs," said Dr. Michael Chippendale, professor of entomology at MU. "The research has gone very well so far. We have made progress in identifying putative plant materials that contain toxins."

The interdisciplinary research is a collaboration among MU, the U.S. Department of Agriculture's Biological Control of Insects Research Laboratory, the University of Oklahoma and the University of Costa Rica. MU is in charge of the entomological, or insect-related, parts of the study.

The first step for the project was to locate and identify plant material that shows resistance to insects in the field. The scientists focused on proteins because of their close relationship to DNA. A tropical location, such as Costa Rica, was a logical place to find such plants because of tremendous insect populations and pressure on the plants. In preliminary tests, the scientists have found a promising plant with innate insect resistance.

At this time, the scientists are screening the extracted plant material to make a general determination about the proper level at which the material becomes resistant to insects. They test the protein extracts by incorporating them into an artificial diet fed to the corn earworm, the Helicoverpa zea insect.

Once the screening step is finished, the scientists will attempt to purify the active ingredient, identify the gene that creates it in plant, clone the gene and produce genetically changed plants that make the active anti-insect protein. Then, the team must test the engineered plants in a containment facility before moving to the field.

An alternate route would be to genetically alter an existing insect-attacking virus to make the virus work more quickly. "The viruses that fight insects now are too slow-acting; they allow the insect to damage too much of the plant before the insect dies," said Dr. Arthur McIntosh, research leader at the USDA Biological Control of Insects Laboratory in Columbia Research Park. "If we could attach the gene that controls this active ingredient to the virus, it would attack the insect more quickly."

Last year American companies spent $1.5 billion on biotechnology research, much of which was proprietary. For instance, one company already has engineered the Bacillus thuringiensis protein, which is toxic to insects, into cotton plants.

"Biotechnology is not pie-in-the-sky research, but it shouldn't be considered a magic bullet either," Chippendale said. "The question now is not whether you can do the engineering, but what you want to engineer into the plant.

"The problem is compliced because insects are tremendously adaptable. They've survived for 250 million years, co-evolving with plants, so you aren't going to knock them out overnight."

Scientists learned first-hand about the adaptability of insects when synthetic insecticides such as DDT were invented in the 1940s. Over time, insects developed resistance to DDT and other pesticides. To combat such adaptability, the scientists may need to eneer several insect-resistant chemicals in the plants at once to combat the development of resistant insect strains.

In addition, the scientists have to make sure plant chemicals repellent to one insect aren't attractive to another and, even more important, that the chemicals produced by the plants won't be toxic to humans or animals.

"For example, cotton genetically engered to resist insects is not used for human food," Chippendale said. "However, the seeds are used in animal feed, and their safety must be demonstrated to be approved."

Funding for the MU project has come through grants of $100,000 from the Washington University Center for Plant Biotechnology and $200,000 from the Midwest Plant Biotechnology Consortium.