COLUMBUS , Ohio – Contrary to what many scientists thought,genetically modified (GM) corn has not yet spread to native maize cropsin southern Mexico.
After analyzing tens of thousands of seedsfrom maize crops grown in 2003 and 2004, researchers from Mexico andthe United States found no evidence of transgenes in these indigenousvarieties.
The finding surprised the researchers, said AllisonSnow, a professor of evolution, ecology and organismal biology at OhioState University . She helped lead the study that appears online thisweek in the Early Edition of the Proceedings of the National Academy ofSciences.
The study is the first published report to survey the frequency of transgenes in native varieties of maize.
Fouryears ago, researchers reported finding four cobs of GM maize in Oaxaca, the southern Mexican state where Snow and her colleagues conductedtheir work. And despite the government's ban on planting thegenetically engineered grain, other unpublished studies confirmed thatGM maize had spread to remote mountain villages in the region.
Ina country whose culture and identity revolve heavily around maize, orcorn – the crop was first developed here thousands of years ago – thethought of importing GM varieties that could contaminate native plantsfrightens many citizens.
“The genetic diversity of native maizeis an important resource with great cultural significance,” Snow said.“If farmers think that their highly revered native plants have beenaltered by transgenes, they might even stop planting them.”
“Noone knew how common transgenic corn was in this area, we thought itcould be as high as 5 to 10 percent,” Snow said. “There is greatpotential for transgenes to come across the U.S. border, with millionsof tons of GM grain imported each year for processed food and animalfeed.”
In 1998, the Mexican government imposed a six-yearmoratorium on the release of genetically modified maize in the country.However, farmers in Mexico are allowed to grow genetically engineeredcrops such as cotton and soybeans.
Over the two-year study, theresearchers gathered more than 153,000 seeds from 870 maize plants in125 fields in Oaxaca . They sent these seeds to two commercialcompanies in the United States that can test for very lowconcentrations of transgenic material in maize seeds.
Theresearchers were looking for traces of two key transgenes – one or bothof which are found in all GM maize crops. Test results showed noevidence of the presence of either transgene from any of the seeds.
“Wenow know that transgenic maize is very unlikely to be growing in Oaxaca,” Snow said. “Mexican farmers who don't want transgenes in their cropswill be relieved to find out that these uninvited genes seem to havedisappeared.”
Transgenes that were present in Oaxaca prior tothis study simply may not have survived, Snow said. Modern GM varietiesmay not be very hardy in Oaxaca, even if they can mate with localplants and gain a degree of hardiness that way.
“Indigenous maizegrows mainly in the mountains – the climate and soils can be prettyharsh there,” she said. “Also, the influx of transgenic seeds may havedeclined if farmers became aware of the issue and took extraprecautions with their seed stocks.”
The Mexican government mightapprove the cultivation of GM maize at some point in the future –meanwhile, transgenic seeds can easily enter Mexico from the UnitedStates, and more cases of wandering transgenes seem likely.
Snowconducted the work with scientists from the Instituto Nacional deEcologia (SEMARNAT) and the National Commission for the Knowledge andUse of Biodiversity (CONABIO ), both in Mexico City; and from GeneticID North America, Inc., in Fairfield, Iowa.
This research wassupported in part by the College of Biological Sciences at Ohio Stateand by the Global Environmental Facility (GEF).
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