Plant biologist says to assess genetically modified agriculture by scientific models

The clear, cold logic of scientific models is the only approach that can take the hysteria out of the hot debate over genetically modified (GM) crops, says a biologist at Washington University in St. Louis.

soybean crops
Eighty percent of the United States soybean crop is genetically modified (GM). A Washington University biologist says that the clear, cold logic of science is the only approach that can take the hysteria out of the hot debate over genetically modified crops.

Barbara Schaal, Ph.D., Spencer T. Olin professor of biology in Arts & Sciences, referred to a famous 1999 Nature paper suggesting that GM corn could kill monarch butterflies. This stimulated lots of detailed research that became the model for risk assessment of GM crops. A subsequent set of papers in the Proceedings of the National Academy of Sciences dispelled the theory that the GM corn, which produced its own insecticide, was highly harmful to monarchs in the field. Schaal said this work was a model for determining the safety of future GM crops and plants.

“GM agriculture needs to be developed based on and guided by scientific principles,” Schaal said. “The question isn’t : do you worry or don’t you worry? The question is: do you worry about this crop, under this condition, in this geographic location?”

The key to conducting these risk assessments is to compare traditional agriculture with GM agriculture, Schaal emphasized.

“Many of the problems attributed to GM agriculture are not unique. They are common in conventional agriculture in general.”

She also warned against oversimplifying the predicted outcomes of GM agriculture, which can be dependent on everything from crop species and geographic location to local agricultural practices and ecological context.

Schaal, who also is professor of genetics at the Washington University School of Medicine, presented at the recent “Conference on Biodiversity, Biotechnology and the Protection of Traditional Knowledge,” co-hosted by the Washington University Center for Interdisciplinary Studies and the Institute for Global Legal Studies, the School of Law, the Biology Department, the Donald Danforth Plant Sciences Center, and the Missouri Botanical Garden. Her presentation, entitled “Biodiversity, Environmental Issues and Agricultural Biotechnology,” focused on the impact of biotechnology on crop biodiversity.

According to Schaal, biotechnology holds both potential benefits and potential risks, and there is no easy answer to the question whether or not biotechnology harms biodiversity. Instead, she advocates the use of a rigorous risk-assessment model to compare current agricultural practices to genetically modified (GM) agriculture.

Potential risks of GM agriculture include affecting non-target organisms such as soil microorganisms and non-pest insects, producing undesirable weedy hybrids that can out-compete wild varieties, and causing genetic cross-pollination, which can alter a species gene pool. Maintaining the genetic integrity of wild crops is especially important in tropical countries such as Brazil, Schaal said, where “intercropping” occurs regularly and GM crops could have a high amount of contact with their wild relatives.

The benefits for GM agriculture are just as numerous. Since 1995, GM practices have enabled farmers to increase their crop yield as well as reduce their use of harmful pesticides, and substitute more environmentally benign herbicides for herbicides that are more toxic or persistent. These changes, in turn, can decrease environmental pollution and increased the biodiversity of local systems. Schaal pointed to the example of beets, where a change in agrochemical use has allowed surrounding weeds to survive longer, resulting in a doubling of the number of arthropod species in these communities. In addition, GM agriculture holds the potential for developing crops that are disease-resistant and produce novel compounds such as pharmaceuticals.

“The first wave of GM crops – soy, cotton, corn – have no close wild relatives in the Midwest so there is little concern for gene mixing,” said Schaal. But she predicted that the next wave of GM crops – including trees for pulpwood, forage grasses and ornamental plants- will be grown in areas with wild relatives nearby, increasing the potential risk to genetic biodiversity.

In addition to her concern for the genetic changes that result from GM agriculture, Schaal is also very aware of its global ramifications and importance.

“High output agriculture is necessary for feeding the world’s population,” she said.

Schaal sees the immediate applications of GM risk-assessment in developing countries, where GM crops are in high demand because of increased pest pressure, but where the naturally high biodiversity and intricately connected ecosystems increase the magnitude of potential risks. These agricultural systems are in contrast to the “monoculture” of the United States.

In the end, the crucial determinants of the future of GM crops might not be as sensational as newspaper headlines have made out in the past, she added.