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August 09, 2010

Fears of pesticide-resistant weeds as GM crops escape into the wild

by Jessica Marshall

Genetically modified canola plants have been found growing wild in the U.S., in some cases far from fields of cultivated genetically modified canola.

Results reported today at a meeting of the Ecological Society of America in Pittsburgh, Penn., suggest that the plants are reproducing on their own, making this the first report of an established population of GM organisms in the wild in the U.S., according to the team.

Meredith Schafer of the University of Arkansas in Fayetteville had been scouring North Dakota without success for weedy relatives of the canola plant, to test whether they had acquired GM traits through cross-pollination with the GM canola plants widely cultivated throughout the state.

"We were in a local grocery store and saw some yellow flowers growing by the side of the road and we thought, 'There's some of the weeds we were looking for.' Lo and behold, it was canola," she said.

The team used test strips that work much like a pregnancy test to determine within 5 minutes whether a plant is carrying one of the two most commonly introduced genes in genetically modified canola.

The genes each produce a protein that lends resistance to two different common herbicides. One gives resistance to Roundup, or glyphosate, and the other gives resistance to Liberty, or glufosinate. These GM traits allow farmers to spray their fields with these herbicides, eliminating other weeds while allowing the herbicide-resistant crop to grow.

"We had genetically modified canola (by the road near) the grocery store and in a large density," Schafer said.

The finding encouraged the team to look further for escaped canola, instead of its weed relative. "We set out across the state in a car. We tested every five miles and where we found canola we did the test," Schafer said. They expanded their search the following season.

The team found canola at 46 percent of the more than 600 stops they made, and 80 percent of the canola plants tested were the genetically modified variety.

The researchers could not test for a third type of genetically modified canola, which represents about 10 percent of the canola planted in North Dakota, so there may be more GM canola present than they detected.

They found high densities of GM canola on major roads, which may result in part from GM seeds being spilled in transit. "We also found a lot in the middle of nowhere, not close to cultivated fields at all," said Cynthia Sagers, Schafer's advisor at the University of Arkansas.

The team's key finding was two plants that each carried both types of herbicide resistance -- a combination that is not commercially available. "The only way this can happen in the wild is if these are perpetuating in the wild, if they're reproducing out there," Sagers said.

There is some chance they did not detect reproducing plants, said Ignacio Chapela of the University of California, Berkeley. The combination could also have been found if a seed carrying both GM traits that was made for research had been released with the commercial product, he said. "We've seen so many cases where the stock gets contaminated with seeds. Research seeds get put into the seeds that are being marketed," he said.

That said, the findings are not surprising, he added. "This is something that was predicted that then has been observed by farmers for many years, especially in Canada where canola is planted so widely."

"We know that they are getting out there," Chapela continued, speaking of the GM plants. "Before it was a rhetorical question, now it is a reality."

The reality that plants can escape cultivation should become part of the discussion about how GM plants are used, Chapela and Sagers agreed.

"I don´t think the findings are necessarily a human health risk," Sagers told Discovery News. But they could be a problem for farmers. "I think the herbicide resistance is going to be a very serious problem for agronomists and farmers in the near future," she said. "I think it could be an environmental problem if we find we've created these herbicide-resistant weeds."

Other GM traits could raise different concerns, including human health risks, she added. "There have been 1100 plants approved for field trials and who knows what those are -- pharmaceutical proteins, drought-resistant crops? Herbicide-resistances are very simple traits. Products in development are more complicated."

Discovery

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