Apparent spread of transgenes from GM corn

In 2001 Ignacio Chapela, an ecologist from the University of California, Berkeley, and co-author David Quist published a highly controversial paper in Nature that appeared to show that genetically engineered genes used in genetically modified (GM) corn (maize) was spreading from GM cornfields in Mexico into traditional corn crops. This set off a firestorm where proponents of GM agriculture declared the paper fatally flawed, pointing out some apparent errors. Accusations of agribusiness conflicts of interest were traded with those of political agendas. Nature subsequently published an "editor's note" stating the journal felt the paper's data were insufficient to support its conclusions. The journal has been careful to say that the editor's note was not the same as a retraction, although advocates of GM crops have claimed it was. A subsequent paper in Proceedings of the National Academy of Sciences (PNAS) by Ohio State plant ecologist Allison Snow failed to find transgenes in maize in the same areas sampled by Chapela and Quist, although questions about that paper were raised on the grounds of statistical power. Now the latest chapter, a forthcoming paper in the journal Molecular Ecology by yet another researcher, Elena Ãlvarez-Buylla of the National Autonomous University of Mexico (UNAM) in Mexico City:

Transgenes from genetically modified (GM) maize (corn) crops have been found in traditional 'landrace' maize in the Mexican heartland, a study says. The work largely confirms a similar, controversial result published in Nature in 2001 and may reignite the debate in Mexico over GM crops.

The paper reports finding transgenes in three of the 23 locations that were sampled in 2001, and again in two of those locations using samples taken in 2004.

[snip]

In 1998, the Mexican government outlawed the planting of GM maize to protect its approximately 60 domesticated landraces and their wild relatives. But newspaper reports suggest that farmers have planted at least 70 hectares of GM maize crops in the northern state of Chihuahua, and it is unclear what repercussions this may have.

Only about 25% of the maize planted in Mexico comes from commercially sold seed; the majority is saved from harvest to harvest. That's why, says Ãlvarez-Buylla, researchers need to pin down whether transgenes really have made it into local crops. "It is urgent to establish rigorous molecular and sampling criteria for biomonitoring at centres of crop origination and diversification," the team writes. (Rex Dalton, Nature News)

The new paper examined thousands of seed and leaf samples, looking for the presence of two genes introduced into GM crops, a gene promoter from the 35S cauliflower mosaic virus, and the nopaline synthase terminator, NOSt. They found them in about 1 in 100 fields. These included fields sampled by Chapela and Quist in the 2001 paper. Snow, the author of the PNAS paper that didn't confirm the Chapela findings, said she believes the new Nature paper is well done and significant for showing how easily the transgene have spread.

The controversy is far from over. The paper was submitted to PNAS but rejected as of insufficient interest, noting in addition the opinion of a reviewer that it could, according to the story in Nature, "gain undue exposure in the press due to a political or other environmental agenda." That was a reviewer's comment, not the editor's view, but one wonders what role that notion played in the decision of PNAS not to publish this paper. It is interesting to observe that PNAS published the Snow paper with negative results, declined to publish the Ãlvarez-Buylla paper with positive results, while Nature published the Chapela paper in 2001, appeared to have gotten its fingers singed in the ensuing brouhaha, and is now running a news piece about a yet to be published paper in another journal that seems to confirm their earlier publication.

No pride or politics involved, though. That's for sure.