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Wandering transgenes may be a worry, expert cautions

Wandering transgenes may be a worry, expert cautions

(April 2, 2001)

Genetically modified crops are perfectly capable of spreading their genetic material to other crop varieties or to natural plant populations, Norman C. Ellstrand, professor of genetics at the University of California, Riverside, cautioned Monday.

"Scientists developing genetically engineered crops should be mindful that transgenes may end up in different lines of the same crops, or in different species," Ellstrand said. "Once they are deregulated, that's it. If they have not considered all the ramifications, we could be in trouble."

Ellstrand made his comments during a symposium on "Plant Biotechnology: Issues Associated with Transgenic Technologies," at the American Chemical Society meeting Monday, April 2, at the San Diego Marriott Convention Center. He was one of five expert panelists.

Ellstrand is an authority in the natural sexual transfer of genetic material from one plant population to another, a field that has become one of the most controversial for plant biotechnology because of the potential for unintended consequences.

For instance, a farmer in Alberta, Canada planted varieties of canola seeds resistant to an individual herbicide. Within a few seasons, he had canola plants that could not be killed with any of the three different herbicides, because the plants had hybridized with each other (see

Subsequently, Kraft recalled Taco Bell Home Originals taco shells in September after an independent lab test found that some of the shells contained an insecticidal compound unique to StarLink corn, a transgenic product approved for animal feed, but not for people.

Ellstrand said that the StarLink situation might have been due to an unintentional mixing of corn seed during transport or storage, although it is also possible that the transgenic variety had cross-pollinated in the field.

"These kinds of anecdotes are significant because it illustrates how easy it is to lose track of transgenes," he said. "Without careful checking, there are plenty of opportunities for them to move from variety to variety."

The results of that kind of spontaneous interbreeding could lead to allergens introduced into the food supply, varieties of weeds that evolve resistance to several herbicides, or even the extinction of certain rare plant species, Ellstrand said.

"Transgenic crops commercially grown to produce pharmaceutical and other industrial biochemicals will pose special challenges for containment if we do not want those chemicals appearing unexpectedly in the human food supply," he said.

Ellstrand's own research has been on hybridization between cultivated radish and wild radish, as well as natural mating between cultivated sorghum and the noxious weed johnsongrass. He has also reviewed the literature and found that natural hybridization between traditionally improved crops and their wild relatives has already led to some problems. He has become convinced that the development of plant biotechnology must acknowledge that all technologies have inherent risks, and that decisions to commercialize the products of plant biotechnology must go hand in hand with prudent consideration of those risks.

"If we have advanced tools for creating novel agricultural products, we should use the advanced knowledge from ecology and population genetics as well as social sciences and humanities to make mindful choices about to how to create the products that are best for humans and our environment," Ellstrand said.

Norman C. Ellstrand
Department of Botany & Plant Sciences
University of California
Riverside CA 92521-0124
Fax: (909)-787-4437

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