Representatives for Monsanto Co. said during a conference call Wednesday that the emergence of the genetically modified strain was an isolated occurrence. It has tested the original wheat stock and found it clean, the company said.
Sabotage is a possibility, said Robb Fraley, Monsanto chief technology officer.
"We're considering all options and that's certainly one of the options," Fraley said.
Fraley said the company has a test it has shared with other countries that could "fingerprint" the exact variety of wheat that carried the gene, and it's awaiting samples from the U.S. Department of Agriculture or the Oregon farmer to test for the exact variety that emerged.
The USDA has said the Oregon wheat is safe to eat and there is no evidence that modified wheat entered the marketplace. No genetically engineered wheat has been approved for U.S. farming.
Consumers' unease with genetically modified crops, particularly those in Europe and Asia, led St. Louis-based Monsanto to end the testing of modified wheat in 2005.
Many countries will not accept imports of genetically modified foods, and the United States exports about half of its wheat crop. Since the announcement of the discovery of the genetically modified wheat in Oregon, Japan one of the largest export markets for U.S. wheat growers suspended some imports. South Korea said it would increase its inspections of U.S. wheat imports.
Supporters of splicing in beneficial genes to modify crops say modifications could help wheat grow in places where it's needed. New traits could make it resistant to disease, pests and, like the rogue strain discovered in Oregon, herbicides.
Opponents argue that genetic modifications carry potential unknown consequences to the humans that consume them and the areas in which they're grown. Changes to the genes of the crops could affect the durability of weeds, making them harder to kill, or the pests that feed on the crops.
The wheat emerged in an Eastern Oregon field in early May and was resistant to the herbicide Roundup. Oregon State University researchers found the wheat had a genetic modification Monsanto used in field testing.
When the test fields were cleared in Oregon in 2001, the seed samples were sent to a USDA deep-storage facility in Colorado. The company's research director, Claire Cajacob, said the company also keeps some samples it is able to test. The rest of the seed is destroyed, she said.
"We've been very careful of how seed is stored and where it's stored," Cajacob said.
The company conducted follow-ups with any entity that possessed the seed with the so-called Roundup Ready gene and confirmed that they shipped it to Colorado or destroyed it, she said.
Testing ended in Oregon in 2001, four years before testing ended nationally. Company representatives said the average wheat seed only stays viable for one to two years in a harsh climate like Eastern Oregon's.
The wheat emerged in a rotational field that was supposed to be fallow in 2013.
Fraley said it's unlikely that other parent stocks were corrupted, or "probably we would have seen it for many, many years over the last decade."
Ninety percent of soft white wheat grown in Oregon, Washington and Idaho is exported, making the state reliant on relationships with foreign markets, specifically those in Asia.
Oregon wheat farmers convened by the Oregon Wheat Commission on Tuesday in Portland said their private conversations center on one question: How did it happen?
"We need to know," said Blake Rowe, chief executive of the Oregon Wheat Commission. "Somehow this gene is out in the environment, but we're waiting for USDA to know how it could have happened."