Another ecological worry about GE crops seemed to have come true with a vengeance in 2000. American scientists reported that maize from the mountains of Oaxaca, Mexico — the birthplace of corn and home to several, revered traditional varieties — contained bits of DNA from GE corn.

The study raised a furor and was later disavowed by the journal that published it. One follow-up survey found no evidence of transgenic contamination, but another reported traces in 1 percent of more than 100 fields sampled.

If GE genes aren’t already in Mexican maize, it’s probably just a matter of time, said Steve Strauss, professor and biotechnology outreach coordinator at Oregon State University. He just doesn’t see it as much to worry about.

Genes jump all the time between conventionally bred crops and other species, he said. Genes from conventionally grown maize in Mexico jumped into teosinte, corn’s wild ancestor. In the Pacific Northwest, genes from wheat conventionally bred to be herbicide-resistant have shown up in jointed goat grass, a weedy relative.

With the current crop of GE genes, the main fear has been that weeds will pick up traits that give them an ecological edge. But that hasn’t been much of a problem so far, compared to the sheer power of natural selection to drive the evolution of pesticide-resistance, said OSU weed scientist Carol Mallory-Smith.

It could be an issue in the future if weeds pick up traits like drought or salt tolerance from GE crops, she said. But the gene transfer could happen with conventionally bred drought tolerance.

In some cases, the consequences of drought-resistant weeds might not be that bad when compared with the benefits of crops that flourish in a drier world, she added.

But people shouldn’t fool themselves into thinking GE crops — or any crop — can be kept in isolation, Mallory-Smith cautioned.

“If you put something into the open environment, we have to admit that we can’t contain it. We can’t retract it.”

Sandi Doughton at: 206-464-2491 or sdoughton@seattletimes.com