PORTLAND — A genetically modified test strain of wheat that emerged to the surprise of an Oregon farmer was likely the result of an accident or possibly tampering, the company that developed it said Wednesday.Representatives for Monsanto Co. said during a conference call Wednesday that the emergence of the genetically modified strain was an isolated occurrence and most likely resulted from an accident or deliberate mixing of seeds. It has tested the parent 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 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.