Calling Poirot: bizarre case of cross-border 'super corn'

It's a border crossing of the worst kind. US biotechnology has spread southward to Mexico, its effects showing up in the native corn of remote southern villages. The high-tech invasion may threaten the birthplace of corn, which is also a key center of biodiversity.

That's the contention, anyway, of two scientists in the United States who have touched off a firestorm.

Scientists around the globe are trading increasingly vitriolic charges over the scientists' findings. Mexican activists claim biotechnology has violated their natural heritage. And an international research center in Mexico faces the unsavory possibility of spending its entire biotech research budget to test its gene banks for the offending material.

Can corn really be so controversial? Apparently so, when the subject is bioengineering. The current corn clash shows how quickly and unexpectedly genetically altered DNA can hop over national borders. It also poses a new question for biotech crops: If the new genetics invades its own cradle, will it weaken the old genetics? Or will it, oddly, enhance it?

No one knows the answer yet.

The skirmish had its beginnings last September, when Mexico's Ministry of the Environment and Natural Resources announced it had found native corn contaminated with bioengineered DNA. The findings seemed to confirm what the two scientists had already discovered in two remote locations of southern Mexico.

But when the scientists – microbial ecologist Ignacio Chapela and graduate student David Quist, both of the University of California at Berkeley – published their findings in the journal Nature in November, the fireworks began.

One Greenpeace activist reportedly called the biotech invasion a worse cultural attack than tearing down Oaxaca's cathedral to build a McDonald's. Last month, the Mexican government enacted a law threatening up to nine years in prison for anyone who commercializes, stores, transports, or releases into the environment a genetically modified organism.

Particularly surprising in the Berkeley study were the remote locations where the altered DNA purportedly appeared. Not only had Mexico banned the planting of such bioengineered corn in 1998, but the affected native corn was growing many miles away from commercial varieties.

How it got there – if it indeed did – remains a mystery. In fact, many crop geneticists doubt it has. They don't like the testing methodology that authors Quist and Chapela used. "Poor experimental design and practices," Transgenic Research, a scientific journal, editorialized.

"Clearly, what they were picking up were false positives," says C.S. Prakash, professor of agricultural biotechnology at Tuskegee University in Tuskegee, Ala.

Such criticisms unleashed further charges and countercharges. "Pro-industry academics are engaging in a highly unethical mud-slinging campaign against the Berkeley researchers," read a statement from 144 nongovernmental organizations. The respected and normally mild-mannered International Maize and Wheat Improvement Center in Mexico weighed in with its own press release decrying "the flamboyant and often misleading headlines that dominate today's debate."

Nearly lost in the furor is the key question raised by the original study: What effect will bioengineered DNA have as it spreads into the environment?

Scientists have long known that genes from their biotech crops would scatter. What the study suggests is that they've moved faster than expected and – perhaps – recombined in surprising ways.

Quist argues that such findings call into question assumptions about these genes behaving the same way whether they're in predictable places, like Iowa, or unexpected places, like southern Mexico.

"We are becoming aware that the most basic conceptions and paradigms of genetic engineering have fatal flaws, which need to be revisited if these concepts fail to stand up to scientific rigor and new experimental evidence," he says.

But crop scientists insist they have taken a hard look at "gene flow." The likelihood of spread is already being reduced by mandated buffer zones and other planting regulations. And spread isn't necessarily bad, they argue. After all, nature and conventional breeders have moved and recombined genes for thousands of years to create today's "natural" foods.

Even Mexico's native corn, at the center of the debate, represents an ever-changing collection of genes, says Marilyn Warburton, a molecular geneticist at the International Maize and Wheat Improvement Center. Over time, genes move in and fall out depending on which varieties local farmers choose to plant the following year.

Dr. Warburton and other crop scientists doubt that altered DNA poses much risk to Mexican corn, since farmers aren't likely to select traits from corn bioengineered for other climates and other pests. But everyone agrees more testing needs to be done.

"There shouldn't be a massive impact of this gene flow on biodiversity," says Luis Herrera Estrella, director of the plant biotech unit at Mexico's National Polytechnic Institute. "Nevertheless, we should make a study to determine the possible consequences."

Meanwhile, the International Maize and Wheat Improvement Center has put Warburton in charge of testing its own gene banks for evidence of the bioengineered corn. So far, the 125 varieties of tested native corn show no signs of contamination. But that's only 1 percent of the holdings – and testing all of them, she says, would eat up the center's biotech research budget.