Today in AgBioView Special from www.agbioworld.org : August 9, 2005
* Duh.... No GM Genes in Mexican Corn
* No Evidence' GM Genes Are Still In Local Mexican Maize
* Four Years On, No Transgenes Found In Mexican Maize
* Biotech Corn Hasn't Mixed With Maize In Mexico, Study Says
* No GM Crops Where Corn Was Born
* Worst GM Pollution Incident' Vanishes (!)
* Evaluating Invasion of GM Corn in Mexico
* GM Maize Not Found in Southern Mexico
Duh.... No GM Genes in Mexican Corn
- C. S. Prakash, AgBioView, www.agbioworld.org, August 9, 2005
Mexican and U.S. scientists have now positively confirmed that
biotech traits are not present in native landraces of maize in
Oaxaca. The researchers screened for two transgene elements that are
present in all commercialized biotech maize varieties using highly
sensitive PCR-based markers. No transgene sequences were found in
125 fields and 18 localities in the State of Oaxaca during 2003 and
2004. The transgenes were not present in spite of approved import of
US and Canadian corn grain into Mexico.
The earlier allegations of harm to maize biodiversity and to rural
campesino farmers were exaggerated and unwarranted. There is an
important lesson to learn here - people should resist drawing
conclusions based on conjecture and unsubstantiated claims. The
scientists conducted a rigorous study to establish a baseline for
comparison in subsequent studies. To their surprise, the transgenes
previously reported were not there. Everyone in Mexico, especially
in the rural communities where a lack of information has produced
concerns, should be made aware of these new findings.
The opportunity for Mexican farmers and society to benefit from
biotech maize has been unnecessarily delayed. Regrettably,
unjustified alarm and unproven allegations have delayed field testing
and the ability to commercialize biotech maize in Mexico. Current
barriers to the testing and approval of GM crops in Mexico are
impeding the adoption of beneficial technologies by Mexican farmers.
Existing Bt maize varieties offer real and important benefits to
Mexican farmers, especially protection from maize pests, such as
earworms, armyworms, borers and rootworms. More than 8 million
farmers in 17 countries around the world are realizing benefits from
biotech crops, including increased productivity, higher economic
returns, reduced labor and agricultural inputs, and higher quality,
as a result of reduced pest damage and fungal disease. Nearly 8 out
of 10 farmers growing biotech crops are small, resource-poor farmers
in developing countries. Farmers of all sizes can readily realize the
benefits, without the need for extensive training, added
infrastructure, and other agricultural supports needed for
introduction of other industrial agricultural practices. Trials of Bt
maize in Argentina, Brazil, Honduras, and South Africa, under
conditions similar to Mexico, have demonstrated significant
improvements in quality and yield.
There is extensive information available to support the safety of
commercial biotech crops. The existing base of safety information
generated by international authorities and experts provides a strong
foundation of evidence that current GM crops pose minimal risks and
provide substantial benefits.
GM crops are among the most extensively tested, well characterized,
and regulated food, feed and fiber products ever developed. Each
commercial biotech crop has been thoroughly assessed for human and
animal health and environmental safety according to well-established,
internationally accepted, scientific standards and guidelines. GM
crops have been found to be as wholesome, nutritious, and safe as
conventional crops by scientific and regulatory authorities
throughout the world. In fact, Mexican authorities have concluded
that GM maize and soybean varieties are safe for human consumption,
and therefore allow grain imports from the U.S. and Canada for use in
After nearly two decades of testing and use, not a single instance of
actual harm to health, safety or the environment has ever been
confirmed for any GM crop currently on the market. The experience of
small and large farmers all over the world also provides clear
evidence that the potential risks are theoretical, while the safety
and benefits have been demonstrated under a wide variety of
environments and agronomic conditions.
What surprises and amazes me is how the authors of the PNAS study
while setting to prove the existence of corn "contamination" in
Mexico (and apparently disappointed at not finding it) continue to
indulge in an anti-GM spin on their negative results and still not
willing to concede the benign nature of biotech crops.
Many news reporters are also scratching their heads. London's
Telegraph blares today "Worst GM Pollution Incident' Vanishes" while
it really should have been "The GM Incident that Never Was". I
question also the judgement of "PNAS" for using a scary language in
its press release (Evaluating Invasion of GM Corn in Mexico) as if these corn are body snatchers!. See
No Evidence' GM Genes Are Still In Local Mexican Maize
- Luisa Massarani, SciDev.Net, August 9, 2005
Research published today (9 August) says that there is no evidence to
support controversial claims made in 2001 that genetically modified
(GM) maize had 'contaminated' local varieties of the crop in Mexico.
In 2001, Nature published research showing that genes from GM maize
had entered wild maize in the Mexican state of Oaxaca despite the
country not allowing GM maize to be grown at the time (see GM maize
found 'contaminating' wild strains).
Although the journal later disowned the paper, its authors, David
Quist and Ignacio Chapela of the University of California at
Berkeley, stood by their claim that one per cent of wild maize cobs
contained genes from GM crops (see Nature backtracks over GM maize
The following year, the Mexican government confirmed that genes from
GM plants had indeed contaminated wild varieties (see Mexico confirms
GM maize contamination). But in the first peer-reviewed follow-up to
Quist and Chapela's study, researchers say that they found no
evidence of genes from GM maize in more than 150,000 seeds taken from
870 plants in Oaxaca in 2003 and 2004.
The authors, led by Allison Snow of Ohio State University, United
States, sampled seeds from 125 fields in Oaxaca. "We conclude that
transgenic maize seeds were absent or extremely rare in the sampled
field," they write in today's online edition of the Proceedings of
the National Academy of Sciences.
One of Snow's co-authors is Exequiel Ezcurra, of Mexico's Environment
and Natural Resources Secretariat. In 2002, Ezcurra told the Mexican
newspaper La Reforma that "genetic contamination of wild Mexican
varieties is taking place". At the time it was thought that GM maize
imported from the United States and planted in Mexico without
authorisation was the source of the genes. Fears arose that this
'contamination' would threaten the genetic diversity of wild maize
varieties, for which Mexico is the origin and centre of diversity.
Snow and colleagues (including Ezcurra) now write, however, that
their results "suggest that many concerns about unwanted or unknown
effects of this process can be discounted at present, at least within
the sampled region".
They accept that GM genes might have been present in 2001 but say
they might have since disappeared. Chapela says he welcomes the research but says it raises more
questions than it gives answers. "It is very difficult to believe
that the contamination we found in 2001 had gone by 2003-2004," he
told SciDev.Net. "I don't believe that is something that happens in
biology -- ever."
Snow's team points out that "evidence that genes are rare or absent
in the sampled area should not be extrapolated to other regions of
Mexico without quantitative data, nor is the current situation likely
to remain static".
Four Years On, No Transgenes Found In Mexican Maize
- Emma Marris Nature, Published online: 8 August 2005; | doi:10.1038/436760a
'Corn found to be free of GM contamination. A grand survey of 150,000
corn seeds has shown up no contamination.'
Four years ago, the discovery of transgenes from genetically modified
(GM) crops in traditional maize varieties in Oaxaca, Mexico,
triggered an almighty row. A new survey suggests that measures taken
since then to purge the crops of transgenes have been effective.
In the original paper, David Quist and Ignacio Chapela of the
University of California, Berkeley, used the polymerase chain
reaction (PCR) to detect two genetic sequences from GM maize in
harvests from 2000 (D. Quist and I. H. Chapela Nature 414, 541-543;
2001)1. Using a variant of the technique called inverse PCR, they
also argued that the transgenes had integrated throughout the genomes
of Mexico's maize varieties.
This was a shocking result, as it suggested that the 'contaminated'
plants were not sporadic hybrids. Instead, it seemed that the
transgenes were entrenched in the traditional varieties at the centre
of natural genetic diversity for maize. "It was as if someone had
gone to the United Kingdom and started replacing the stained-glass
windows in the cathedrals with plastic," says Jorge Soberón, a former
Mexican government scientist now at the University of Kansas in
Lawrence and a co-author of the new study.
The inverse-PCR methodology used by Quist and Chapela soon came under
fire, however, and Nature stated that it would not have published the
paper if the criticisms had cropped up while the paper was under
review. But even so, few experts questioned the basic finding that
some transgenes had flowed into Mexican maize.
Despite an official moratorium on GM planting, this could have
resulted from local farmers planting GM maize intended for food use
that was imported from the United States. Unpublished work by Mexican
government scientists also found transgenes, but a thorough and
systematic confirmation was lacking.
That survey has now been done - and to the surprise of the authors,
they found no transgenes at all. The sample of more than 150,000
seeds from 2003 and 2004 was negative for the same two transgenic
sequences (S. Ortiz-García et al. Proc. Natl Acad. Sci. USA
doi10.1073/pnas.0503356102; 2005)2. "I was convinced we were going to
verify Quist and Chapela's results," says co-author Exequiel Ezcurra,
head of the Biodiversity Research Center of the Californias at San
Diego Natural History Museum and former president of the National
Institute of Ecology in Mexico City.
The authors speculate that transgenes were present in the fields in
2000, but dropped out of local maize varieties thanks to a programme
of education for farmers and a reduction in GM maize imports. The
researchers, led by Allison Snow of Ohio State University in
Columbus, did not directly replicate Quist and Chapela's inverse-PCR
methods. But Snow says that the apparent failure of the transgenes to
persist down the generations contradicts the idea that they were
entrenched in the genomes of the traditional maize varieties.
Brian Johnson, who follows developments in agricultural biotechnology
for the government conservation agency English Nature, is unsurprised
at this finding: "If there are transgenes in Mexico, or anywhere
else, I would expect that they would be difficult to find - they
would be rather sporadic." Johnson says he never believed they were
permanently incorporated into the genes of traditional maize
Chapela stands by his findings, saying it is "naive" to believe an
education programme could have such a dramatic effect. He claims that
the commercial labs used by the research team to do the screening
used conservative thresholds for declaring a match with the transgene
sequences. But Bernd Schoel, director of research at one of those
labs - Genetic ID of Fairfield, Iowa - says the screen was as
sensitive as possible, given the sample size.
1. Quist D. & Chapela I. H. et al. Nature, 414. 541 - 543 (2001).
2. Ortiz-GarcĂ?a S., et al. Proc. Natl Acad. Sci. USA,
Biotech Corn Hasn't Mixed With Maize In Mexico, Study Says
- Eric Hand, August 8, 2005 The St. Louis Post-Dispatch
Genetically modified corn hasn't mixed with native maize in southern
Mexico, according to a study posted online this week by the
Proceedings of the National Academy of Sciences. The study
contradicts results from four years ago, when scientists said
modified corn genes had moved into the traditional crops, called
maize in Mexico.
But scientists said gene flow - which leads to the movement of traits
from one plant to another - is inevitable for both traditional and
engineered plants because it happens during the constant, natural
process of crossing. "That's what plants do ...," said Roger Beachy,
director of the Donald Danforth Plant Science Center in Creve Coeur.
"They've been doing it for millions and millions of years."
The flow of an engineered gene isn't different from the movement of
genes during the making of a hybrid flower or fruit. Missouri
Botanical Garden Director Peter Raven said people need to stop
"treating transgenes like viruses." Instead, Raven and Beachy argue,
the consequences of gene flow need to be examined individually,
country by country, plant by plant, gene by gene. "If there is a
mixing, which there will surely be, the question is, 'What's the
biological impact?'" Beachy said. "Is it a positive or a negative
Four years ago, two scientists at the University of California at
Berkeley said in the journal Nature that genetic mixing in southern
Mexico was "relatively common" and "maintained in the population from
one generation to the next." The study received attention because in
1998 Mexico imposed a freeze on planting of biotech crops. The
mixing, if it happened, was because engineered corn had slipped
across the border. The study later was discredited for its shoddy
In the new study, Ohio State University ecologist Allison Snow looked
for the unique markers of genetic modification in an analysis of more
than 150,000 corn kernels harvested in 2003 and 2004 from Oaxaca,
Mexico. She concluded exactly the opposite of the Berkeley
scientists: Genetic mixing was nonexistent. The maize was pure. And
if transgenes existed at the time of the Berkeley study, they were
eliminated in a few generations.
Barbara Schaal, a Washington University biologist, said the study
raised doubts as to whether there was ever gene flow. But it will
happen eventually - for better or for worse, she said. Often,
genetic mixing results in positive traits farmers want. Sometimes the
traits are neutral and are eliminated in a generation or two. Other
times gene flow can be bad.
Undesirable gene flow has happened naturally and with genetically
modified plants. In Canada, canola has been engineered to resist the
Monsanto weed killer Roundup. The engineered canola has crossed with
existing canola and caused problems for farmers who want to certify
their canola as organic.
An international panel of scientists commissioned to study the issue
of Mexican maize concluded in 2004 transgenes would cause no harm but
said Mexico could regulate it however it wanted.
Schaal also said some plants exchange genes more readily than others.
Rice plants, for instance, only breed with themselves. Moreover, rice
grains often are polished before being exported, which sterilizes the
seed. That's why Schaal thinks rice is a good candidate for
pharmaceutical applications. Ventria, a California-based
pharmaceutical company, has proposed such an operation for Missouri.
There would be very little chance of the pharmaceutical traits
getting into the food supply, she said.
On the other hand, corn genes easily mix because corn plants like to
breed with neighboring cousins, Snow said. Also, exported corn grains
often are viable seeds. Just as transgenes appear to be eliminated
in Mexican maize, the Mexican government has taken action that likely
will encourage more genetically modified corn to be planted.
President Vicente Fox signed a law that ends the de facto freeze and
encourages biotechnology through a process that will give special
attention to preserving the biodiversity of maize.
No GM Crops Where Corn Was Born
- Maggie Fox, Independence (South Africa), August 9 2005 http://www.iol.co.za
Washington - The Mexican region where modern corn originated shows no
traces of a genetically engineered contamination that caused an
international uproar and created tension over United States corn
imports, researchers have said.
"If they were there, they are gone," Exequiel Ezcurra, a former
Mexican official who is now with the San Diego Natural History Museum
in California, said in a telephone interview on Monday. He said an
educational campaign to make farmers in Oaxaca state aware of the
issue evidently has worked, and the farmers apparently were able to
eliminate the undesirable corn imports.
'We were incredibly surprised when we found nothing'
Ezcurra worked on the original study and the new analysis published
in this week's issue of the Proceedings of the National Academy of
Sciences. When the genetically modified corn was discovered in
September 2001 deep in mountainous Oaxaca, it raised alarms around
the world and sparked protest from global activist groups like
The culprit was clear - Mexico imports between 5 million and 6
million tons of maize from the US each year, and close to half of all
US corn is genetically modified. Most is altered to produce a
naturally occurring toxin known as Bacillus thuringiensis, or Bt, to
ward off pests.
Mexico allows GM cotton and soybeans, but not corn.
The government says it wants to protect the biodiversity of Mexico's
corn because the nation is home to the world's richest corn gene
pool. zcurra, Allison Snow of Ohio State University and colleagues
did another sampling and found no evidence of gene-engineered corn.
"We sampled maize seeds from 870 plants in 125 fields and 18
localities in the state of Oaxaca during 2003 and 2004," they wrote
in their report published in the Proceedings of the National Academy
of Sciences. They tested more than 150 000 seeds and found no
evidence of transgenes - the spliced-in genes used to engineer the
corn. "We now know that transgenic maize isn't growing in Oaxaca,"
Snow said in a statement. "Mexican farmers who don't want transgenes
in their crops will be relieved to find out that these uninvited
genes seem to have disappeared."
Ezcurra said he also was relieved by the findings. "We were
incredibly surprised when we found nothing," he said. "If transgenic
material had got into the community because people were planting
imported grain inadvertently, then from 2001 onwards, the communities
were well-informed and they knew how to avoid planting grain of
This finding suggests that even if gene-engineered crops escape the
fields they are intended for, the problem can be corrected quickly,
Ezcurra and Snow said. "There is great potential for transgenes to
come across the US border, with millions of tons of GM grain imported
each year for processed food and animal feed," Snow said.
"If farmers think that their highly revered native plants have been
altered by transgenes, they might even stop planting them," she added.
Worst GM Pollution Incident' Vanishes
- Roger Highfield, Telegraph (UK), August 9, 2005 http://www.telegraph.co..uk/
What was billed by the media as the world's worst incident of
pollution by genetically-engineered crops, one that provoked a row
among scientists, has vanished, says a study published today.
Four years ago, researchers reported finding cobs of genetically
modified maize in Oaxaca, Mexico, suggesting that GM maize (corn)
from the US had invaded a traditional maize variety.
In a country whose culture and identity are linked to maize - the
crop was developed there thousands of years ago - the thought of GM
varieties that could contaminate native plants was abhorrent.
Then the leading journal Nature disowned the paper that described the
discovery by researchers at the University of California, Berkeley.
The paper had sparked a protest to Nature by 100 biologists and was
disowned by the Mexican government after its scientists could not
repeat the experiment. The anti-GM lobby portrayed the row as an
attempt to discredit the research and as part of a biotech industry
Now a two-year study published by Prof Allison Snow's team, of Ohio
State University, in Proceedings of the National Academy of Sciences,
says genetically modified corn has not spread to native maize crops
in southern Mexico.
The researchers gathered more than 153,000 seeds from 870 maize
plants in 125 fields in Oaxaca, for the first survey of foreign
"transgenes" in native varieties, and found no evidence of
contamination. The finding surprised the researchers, said Prof Snow,
because millions of tons of GM grain were imported from the US each
year for processed food and animal feed.
Transgenes in Oaxaca before this study may not have survived, she
said. Modern GM varieties may not be hardy in Oaxaca even if they
could mate with local plants. The genetic diversity of native maize
was an important resource with great cultural significance. "If
farmers think their highly revered native plants have been altered by
transgenes, they might stop planting them."
Evaluating Invasion of GM Corn in Mexico
- PNAS Online Early Edition, August 8, 2005
Researchers have found no evidence that genetically modified (GM)
maize (corn) from the U.S. invaded local maize crops in Mexico during
2003 and 2004. Bred for insect and pesticide resistance, GM maize has
been grown commercially by the U.S. since 1996 but has never been
approved for cultivation in Mexico. In 2000, however, GM maize was
found in fields of Mexican maize grown locally in the state of
Oaxaca. Some Mexican farmers perceive GM maize to be a threat to the
cultural identity and genetic diversity ˙of openly pollinated local
To better understand the degree of GM maize infiltration, during
2003-2004, Sol Ortiz-Garcia and colleagues sampled maize seeds from
125 fields in 18 localities in Oaxaca. The seeds were screened for
two artificially introduced DNA sequences that are present alone or
in combination in all commercial varieties of GM maize. The
researchers did not detect these specific DNA sequences in any
specimens and concluded that GM maize seeds were absent or extremely
rare in the fields sampled in 2003 and 2004. This s˙tudy provides a
useful frame of reference for understanding the implications of
inadvertent dispersal of GM crops.
Genetically Modified Maize Not Found in Southern Mexico
- Ohio State University, August 8, 2005
Contrary to what many scientists thought, genetically modified (GM)
corn has not yet spread to native maize crops in southern Mexico.
After analyzing tens of thousands of seeds from maize crops grown in
2003 and 2004, researchers from Mexico and the United States found no
evidence of transgenes in these indigenous varieties. The finding
surprised the researchers, said Allison Snow, a professor of
evolution, ecology and organismal biology at Ohio State University.
She helped lead the study that appears online this week in the Early
Edition of the Proceedings of the National Academy of Sciences.
The study is the first published report to survey the frequency of
transgenes in native varieties of maize.
Four years ago, researchers reported finding four cobs of GM maize in
Oaxaca, the southern Mexican state where Snow and her colleagues
conducted their work. And despite the government's ban on planting
the genetically engineered grain, other unpublished studies confirmed
that GM maize had spread to remote mountain villages in the region.
In a country whose culture and identity revolve heavily around maize,
or corn - the crop was first developed here thousands of years ago -
the thought of importing GM varieties that could contaminate native
plants frightens many citizens.
"The genetic diversity of native maize is an important resource with
great cultural significance," Snow said. "If farmers think that their
highly revered native plants have bee n altered by transgenes, they
might even stop planting them."
"No one knew how common transgenic corn was in this area, we thought
it could be as high as 5 to 10 percent," Snow said. "There is great
potential for transgenes to come across the U.S. border, with
millions of tons of GM grain imported each year for processed food
and animal feed."
In 1998, the Mexican government imposed a six-year moratorium on the
release of genetically modified maize in the country. However,
farmers in Mexico are allowed to grow genetically engineered crops
such as cotton and soybeans.
Over the two-year study, the researchers gathered more than 153,000
seeds from 870 maize plants in 125 fields in Oaxaca. They sent these
seeds to two commercial companies in the United States that can test
for very low concentrations of transgenic material in maize seeds.
The researchers were looking for traces of two key transgenes - one
or both of which are found in all GM maize crops. Test results showed
no evidence of the presence of either transgene from any of the seeds.
"We now know that transgenic maize isn't growing in Oaxaca," Snow
said. "Mexican farmers who don't want transgenes in their crops will
be relieved to find out that these uninvited genes seem to have
Transgenes that were present in Oaxaca prior to this study simply may
not have survived, Snow said. Modern GM varieties may not be very
hardy in Oaxaca, even if they can mate with local plants and gain a
degree of hardiness that way. "Indigenous maize grows mainly in the
mountains - the climate and soils can be pretty harsh there," she
said. "Also, the influx of transgenic seeds may have declined if
farmers became aware of the issue and took extra precautions with
their seed stocks."
The Mexican government might approve the cultivation of GM maize at
some point in the future - meanwhile, transgenic seeds can easily
enter Mexico from the United States, and more cases of wandering
transgenes seem likely.
Snow conducted the work with scientists from the Instituto Nacional
de Ecologia (SEMARNAT) and the National Commission for the Knowledge
and Use of Biodiversity (CONABIO), both in Mexico City; and from
Genetic ID North America, Inc., in Fairfield, Iowa.
This research was supported in part by the College of Biological
Sciences at Ohio State and by the Global Environmental Facility
(GEF). Contact: Allison Snow, 614-292-3445; Snow.firstname.lastname@example.org Dr. Snow
is traveling in Michigan, Maine and Texas during the month of August.
She can be contacted by email address above. From August 1-5, she can
be reached by telephone at the University of Michigan Biological
Station at 231-539-8413. After August 5th, please contact her by
email and she will return your call promptly.