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Mexico's GM corn
shocks scientists
The Guardian (London) November 30, 2001
Researchers baffled
as ancient variety of maize tests positive for
modified organisms in area where no engineered crops are grown
By John Vidal
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
wind.
"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.
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