GMOs: Friends or Foes
Opinions vary on what genetically modified organisms mean for Minnesota's environment.
By Mary Hoff. Illustrations by Michael Schmidt
The scene could be one from my grandparents' lives as easily as from my own: row upon row of ripening corn, tassels held high, lanky leaves soaking up the hot August sun, fat cobs harboring the fruit of yet another growing season.
But this corn differs from that my grandparents grew in one dramatic way. Spliced into its DNA is a snippet of genetic material taken from a microbe known as Bacillus thuringiensis, Bt for short. The snippet produces a protein that kills the European corn borer, a profit-robbing pest.
"Really?" my grandmother, were she here today, would say, her eyebrows twitching with incredulity. For her generation, genetic engineering was about as plausible as time travel, or alien spaceships landing in the oats. Today, however, genetically modified organisms--GMOs--are common as houseflies in the cow barn. Last summer more than one-half of the U.S. soybean crop, one-fourth of the corn crop, and 61 percent of the cotton crop were genetically modified. According to Minnesota Department of Agriculture biotechnologist Mary Hanks, more than 250 types of transgenic plants--including wheat, sugar beets, potatoes, petunias, and other species imbued with a smorgasbord of traits from herbicide tolerance to improved amino acid content--have been released in Minnesota. Hundreds of other GMOs are under development around the world. Fast-growing fish, disease-resistant mollusks, medicinally enhanced bananas--the list goes on.
What do these organisms mean for the environment?
Noel Kjesbo thinks at least some are good news. A few years back the Red River Valley farmer began planting soybeans genetically modified to be tolerant to glyphosate, a relatively environmentally benign weed killer. By allowing him to apply glyphosate after his soybeans have sprouted, the move has helped him reduce herbicide use.
"It was not uncommon for me to use a tank mix that had in it three or four chemicals," Kjesbo says. Now he's down to one. "I'm applying fewer pounds of chemical per acre by far now than I was with my old recipe," he says.
The opportunity to cut down on herbicides is just one potential environmental benefit of GMOs. Glyphosate tolerance can also help protect soils when used with conservation tillage, an erosion-reducing cropping practice. According to Kjesbo, use of glyphosate-tolerant soybeans also reduces profit-robbing crop injuries that can occur when multiple herbicides are used together. And insect-resistant crops can reduce the need for other pest controls. According to the National Agricultural Biotechnology Council, use of such GMOs has produced "significant decreases in the use of chemical insecticides" in both corn and cotton.
To University of Minnesota plant pathologist Nevin Young, the biggest benefit is the technology's promise for increasing per-acre productivity, and so easing the toll of tilling.
"The overall potential is profound in terms of decreasing the amount of land that needs to be cultivated in the first place," Young says.
But the picture is far from clear, Young says. Though transgenic crops have the potential to help farmers cut back on herbicides and pesticides, "there is considerable disagreement about the extent to which this is reducing chemical use," he says.
In fact, GMOs could make some herbicides and pesticides less effective by increasing exposure and so increasing the rate at which weeds and pests become resistant to them.
"Right now a lot of people use Bt in various forms for organic gardening and integrated pest management," says Wayne , Department of Natural Resources regional environmental assessment ecologist. "We could potentially lose that as a tool should resistance develop."
Some scientists worry about impacts on other living things. Several years ago researchers shelved development of a strain of the bacterium Klebsiella planticola, which had been engineered to improve conversion of agricultural wastes into ethanol, because byproducts of the process killed wheat. A Cornell University research team made international news in 1999 when it reported the deaths of monarch butterfly caterpillars that nibbled on milkweed dusted with Bt corn pollen. Other researchers have shown that lacewing larvae and ladybird beetles--both considered agricultural allies because of their appetite for crop pests--are harmed by eating insects that have eaten crops engineered with pesticidal properties.
According to David Frederickson, president of the Minnesota Farmers Union and member of the U.S. Department of Agriculture's Advisory Committee on Agricultural Biotechnology, research has shown that Bt corn roots release active toxins into the soil, and that Bt toxin can remain active in the soil for months.
"Is it affecting soil fauna?" asks Barstad. "Is it getting into the groundwater and then getting into wetlands or streams?"
And then there's the potential for transgenic genes to escape cultivation as plants interbreed with wild relatives. For crops such as corn that lack close cousins in Minnesota, that's not a problem. But for sunflowers and others that do have cousins here, it's a different story.
"I think the evidence is clear that this could happen, and probably will in the kinds of plants that reproduce through outcrossing," Young says. "I have no doubt in my mind."
What would be the impact of such a cross? Depending on the plant, trait, and circumstances, it could be negligible--or it could rival that of invasive exotic species such as purple loosestrife and buckthorn. "I believe ecologists and population biologists should take this seriously," says Young, "and carry out experiments to learn more about how transgenes potentially move to wild relatives of cultivated crops."
Other environmental concerns range from the impact of GMOs' better insect control on insect-eating birds, to GMOs' role in promoting large-scale monoculture over more diversified farming. The Union of Concerned Scientists warns that transgenic plants that produce nonfood products such as plastics or medicines could harm foraging wildlife. The union also suggests that crops engineered to reduce susceptibility to viruses could unwittingly lead to development of new, more troublesome viruses.
The debate goes on. Last fall the U.S. Environmental Protection Agency released a report concluding that registered Bt corn and cotton varieties have no "unreasonable adverse effects" on nontarget plants or animals. GMO supporters note that fears live largely in the realm of mights and maybes rather than in proven harm. They also point out that risks can be managed--for example, farmers can delay development of Bt resistance by planting part of their fields with conventional seed. In this business, virtually every claim has a counterclaim--and virtually every counterclaim does too.
If critics are concerned about the environmental implications of transgenic farm crops, they're downright queasy about a newer kid on the block: transgenic trees.
In 1998 Michigan Technological University researchers planted an experimental plot of poplar in Koochiching County. The trees were genetically altered for reduced lignin content (the substance that binds tree fibers together). The introduction went by relatively unnoticed. But when the Oregon State University-based Tree Genetic Engineering Research Cooperative announced plans to test insect-resistant, herbicide-tolerant transgenic hybrid poplars in Otter Tail County last spring, it caught Barstad's eye. Though the DNR has no official position on the overall use of GMOs, Barstad and some other DNR staff members have concerns similar to those for conventional crops, only more so. Their concern is that Bt, in its natural form, is used to control forest pests in Minnesota, so development of resistance could cause big problems here. Also, Barstad notes that Minnesota is home to four native poplar species to which hybrid poplars could potentially spread their novel genes.
A big concern over the introduction of transgenic trees stems from the fact that trees can spread their genetic material in many ways, via seed, pollen, and root suckers. No one knows what would happen if the novel genetic material were to escape from a managed plantation. The introduction of altered genetic material into a forest ecosystem could have significant unintended consequences.
DNR tree improvement specialist Rick Klevorn shares Barstad's concern about the transfer of genes to native species. He also worries about the long-term fate of Bt toxin produced by transgenic trees.
"The Bt gene is expressed throughout the organism, so there's the potential harm from any plant parts on the site," he says. "When you harvest transgenic trees, what about the slash on the site, what about the leaves when they fall in the fall?" No one knows what leftover Bt toxin might do to nontarget organisms in the soil or in nearby streams and rivers.
Balance With Benefits
So, does Klevorn contend that we ought to put a kibosh on genetically modified trees? Not a bit. "I don't think potential risks should in any way inhibit the research, because the potential benefits are too great," he says.
TGERC associate director Richard Meilan agrees: "One reason we're doing the things we do is because we think it will have a positive effect on the environment."
Both Meilan and Klevorn note that transgenic trees, like transgenic farm crops, have the potential to cut the need for harsher pest- and weed-control measures. And herbicide-tolerant trees could make it easier for growers to kill competing vegetation in tree plantations, enhancing the plantations' productivity and so reducing harvest pressure on wilder forests.
"This technology may save some naturally occurring forests. I think that's a huge, huge benefit," Klevorn says.
The low-lignin poplar project boasts yet another potential environmental boon: cleaner paper production. Because lignin must be removed from wood to make paper, reduced lignin content means fewer byproducts to pollute air and water and less need for chlorine, a notorious papermaking pollutant used to remove lignin, says Vincent Chiang, director of Michigan Tech's Plant Biotechnology Research Center. Chiang says the lignin-light trees also grow faster and produce more pulp than conventional poplar; so less land, water, and other inputs are needed.
"I think certainly the potential benefit is going to outweigh the potential risk," Chiang says.
While touting benefits, transgenic tree boosters are also working to minimize the potential hazards. One of the goals of TGERC's Minnesota field trial, according to Meilan, is to "reduce the risk of insects becoming resistant to the product of the transgene." TGERC is developing a computer model to help predict movement of transgenes in the environment, and TGERC researchers are looking for ways to engineer sterility into the trees.
According to Klevorn, such precautions can go a long way toward heading off potential problems with GMOs. "We'll just manage the bejabbers out of these trees," Klevorn says. "If we see something dangerous, of course we need to sound the alarm; but for genetically engineered trees in Minnesota right now, it's not dangerous."
As experts debate the environmental implications of genetically modified plants, they're also bracing for the next wave--genetically modified animals. Perhaps the closest to commercial reality in the United States is a transgenic salmon. Developed by Canadian researchers, it grows four to six times faster than its wild relatives.
The potential environmental payoff is grand. Genetic engineering could reduce the environmental toll of using fish to feed a hungry world by enhancing production efficiency and cutting disease loss. But there are serious concerns over what would happen if the seafood-to-be wandered.
"From an environmental point of view and from a fish management standpoint, we don't know what effect these critters would have if they were released to the wild," says DNR fisheries research manager Jack Wingate. He notes that the agency doesn't even look kindly on moving wild fish from one part of the state to another because it doesn't want to alter the genetics of local stock.
"You can imagine our concerns if you have an organism that's been genetically modified," he says.
Transgenic fish were first produced in Minnesota in the mid-1980s by a University of Minnesota research team, which included fisheries professor Anne Kapuscinski. That early work led Kapuscinski to a deep-rooted concern about the impact genetically modified fish would have on the environment if they were to escape the confines of fish farms and interbreed with, outcompete, or prey on native species. Today Kapuscinski is a member of the USDA's Advisory Committee on Agricultural Biotechnology. Though she strongly advocates doing an individual risk analysis for every GMO, she is particularly uneasy about the commercialization of genetically modified aquatic animals.
"Fish and shellfish are really quite important," she says. "They all have wild relatives, and they're notorious for escaping into the wild and being impossible to call back."
Wingate concurs. "I think it has the potential to be a bad thing," he says. "We need more information before we can make a nice, definitive yes or no. Nothing's foolproof. I think at some point in time we may look at genetically modified fish much as we do exotic fish that are now raised in the state in culture facilities where the likelihood of escape is greatly reduced to practically nil. But I think there's a lot of hurdles and questions that have to be overcome and answered."
Mary Hoff is a free-lance science writer from Stillwater and the Production Coordinator for the Volunteer. Michael Schmidt is a free-lance illustrator from St. Paul.