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from UK Press
Mexico's GM corn shocks scientists
Researchers baffled as ancient variety of maize tests positive for
modified organisms in area where no engineered crops are grown
Thursday November 29 2001
One of the world's oldest varieties of maize has been "contaminated"
by genetically modified organisms, say US researchers who have had
their work confirmed by the Mexican government.
The findings in the Sierra Norte de Oaxaca region will stoke the row
about whether it is possible to control GM crops and their potential
threat to genetic diversity.
The group of researchers from the University of California, Berkeley,
detected the contamination in October last year while working with a
biological laboratory in the region. They compared indigenous corn
with samples known to be free from genetic engineering, as well as
with genetically modified varieties.
Their results, published yesterday in the science journal Nature,
showed that four of six samples of native criollo corn taken from
fields contained a genetic "switch" commonly used in GM crops, and
that two of the samples were found to have another DNA segment
commonly inserted by genetic engineers. A further sample contained a
commonly inserted gene that prompts the plant to produce a poison.
The researchers alerted the Mexican government which did its own tests
in 22 communities. They confirmed in September this year that
transgenic DNA had been found in 13 of them, with contamination of
between 3% and 10%.
The results are surprising because Mexico, which is the genetic home
of maize, has banned the growing of GM maize since 1998, and the last
known GM crops grown in the region were almost 60 miles from where the
contaminated maize was found.
It was not clear yesterday when the contamination took place, but the
scientists speculated that it originated from GM maize bought from the
US as food aid for the impoverished region in central Mexico, and had
progressed over time via multiple pollinations.
It is not thought that that the cross-pollination happened over long
distances, because corn pollen is heavy and does not travel far on the
"I repeated the tests at least three times to make sure I wasn't
getting false-positives," the lead author of the report, David Quist,
said. "It was initially hard to believe that corn in such a remote
region would have tested positive."
"This is very serious," said Ignacio Chapela, assistant professor of
microbial ecology at Berkeley's College of Natural Resources, "because
the regions where our samples were taken are known for their diverse
varieties of native corn, which is something that absolutely needs to
be protected. We can't afford to lose that resource."
But Luis Solleiro, director of the Mexican biotechnology trade
association, denied that the country's rich genetic diversity was
threatened. "The data suggests that any transgenic corn is at a very
low level," he said. "This level, or even greater presence, would not
adversely affect the genetic diversity of native strains."
Greenpeace, Friends of the Earth and other groups that oppose GM crops
argued yesterday that even a low level of genetic contamination was
highly significant in a centre of diversity and origin.
"The genetic contamination is likely to multiply through pollen flow
and spread further to other traditional varieties and wild relatives
growing in the area", Doreen Stabinsky, from Greenpeace USA, said.
"This is likely to be only the tip of the iceberg, as plants in other
parts of Mexico have not yet been investigated."
The UN Food and Agriculture Organisation is concerned that GM crops
may pollute the gene pool of conventional relatives in the same area
or nearby, depending on wind and insects. "If there is no barrier to
pollination, you get this potential hazard," said Ricardo Labrada
Romero, the FAO's plant protection officer.
The research adds to concerns that GM crops may be out of control. The
Canadian government's agricultural de partment last month reported
that stray pollen and seed from genetically modified oilseed rape
crops was now so widespread that it was difficult to grow conventional
or organic strains without them being contaminated.
More than 100m acres [33m hectares] of GM crops have been grown,
mostly in the US and Canada.