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Despite Mexico's 3-year-old moratorium
on the use of genetically altered corn, scientists have detected
genetically modified DNA in wild maize in the mountains of
the state of Oaxaca.
Wayward genes from genetically modified
corn that is widely grown in Canada and the United States
are spreading in remote mountainous regions of Mexico.
Up to 70% of wild Mexican maize now carries
transgenes that could only have come from genetically engineered
crops. The transgenes, which scientists borrow from viruses
and bacteria, have been engineered into GM crops.
The
spread of altered genes in the birthplace of domesticated
corn could have "very serious consequences."
Scientists add foreign genes to crops
to boost resistance to pests and drought, or in come cases,
to make them tolerant to chemicals that can kill weeds. Close
to 30 million hectares of GM crops have been grown around
the world, much of them in Canada.
Scientists believe it is only a matter
of time before many transgenes that have been added to plants
spread around the world, incorporating themselves in the DNA
of non-GM crops. Potatoes, rice and cotton are sure to be
affected.
The prospect is particularly worrisome
when one considers some of the crops being engineered in the
lab. One U.S. firm is working on corn with anti-spermicidal
properties, which might have disastrous consequences if
it ever spread to food crops.
The areas of diversification -- the genetic
bank account of diversity -- for this crop, corn, is compromised.
Oaxaca is the region where corn was domesticated. Even today
most of the diversity of corn is found there.
Each year, breeders go to Oaxaca to look
for beneficial genes in wild corn that could be transferred
into commercial crops. For instance, wild corn might contain
genes that make it resistant to pests or better able to survive
environmental conditions, such as drought.
The spread of modified DNA into wild
maize may represent a "cashing in on the bank account"
of diversity. We were not
supposed to see these moving around in the environment.
Researchers at Berkeley sampled several
varieties of maize native to Oaxaca to see whether they contained
material from two strains of genetically modified corn used
in the US.
Five of the seven types of maize they
sampled tested positive for genetically modified material.
In contrast, tests on maize from Peru and a sample saved from
the 1971 growing season in Oaxaca were negative.
Corn is one of the most important crops
in the world. The spread of genetically modified material
could be wider since the same principle applies to other crops
such as rice and wheat.
Nature
November 29, 2001;414:541-543
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