www.czu.cz ; www.usab-tm.ro ; www.raupp.info

Modified genes from crops in a GM crop trial have transferred into local
wild plants, creating a form of herbicide-resistant "superweed", the
Guardian can reveal, July 2005 by Paul Brown.

The cross-fertilisation between GM oilseed rape, a brassica, and a
distantly related plant, charlock, had been discounted as virtually
impossible by scientists with the environment department. It was found
during a follow up to the government's three-year trials of GM crops which
ended two years ago.

The new form of charlock was growing among many others in a field which had
been used to grow GM rape. When scientists treated it with lethal herbicide
it showed no ill-effects.

Unlike the results of the original trials, which were the subject of
large-scale press briefings from scientists, the discovery of hybrid plants
that could cause a serious problem to farmers has not been announced.

The scientists also collected seeds from other weeds in the oilseed rape
field and grew them in the laboratory. They found that two - both wild
turnips - were herbicide resistant.

The five scientists from the Centre for Ecology and Hydrology, the
government research station at Winfrith in Dorset, placed their findings on
the department's website last week.

A reviewer of the paper has appended to its front page: "The frequency of
such an event [the cross-fertilisation of charlock] in the field is likely
to be very low, as highlighted by the fact it has never been detected in
numerous previous assessments."

However, he adds: "This unusual occurrence merits further study in order to
adequately assess any potential risk of gene transfer."

Brian Johnson, an ecological geneticist and member of the government's
specialist scientific group which assessed the farm trials, has no doubt of
the significance. "You only need one event in several million. As soon as it
has taken place the new plant has a huge selective advantage. That plant
will multiply rapidly."

Dr Johnson, who is head of the biotechnology advisory unit and head of the
land management technologies group at English Nature, the government nature
advisers, said: "Unlike the researchers I am not surprised by this. If you
apply herbicide to plants which is lethal, eventually a resistant survivor
will turn up."

The glufosinate-ammonium herbicide used in this case put "huge selective
pressure likely to cause rapid evolution of resistance".

To assess the potential of herbicide-resistant weeds as a danger to crops, a
French researcher placed a single triazine-resistant weed, known as fat hen,
in maize fields where atrazine was being used to control weeds. After four
years the plants had multiplied to an average of 103,000 plants, Dr Johnson
said.

What is not clear in the English case is whether the charlock was fertile.
Scientists collected eight seeds from the plant but they failed to germinate
them and concluded the plant was "not viable".

But Dr Johnson points out that the plant was very large and produced many
flowers.

He said: "There is every reason to suppose that the GM trait could be in the
plant's pollen and thus be carried to other charlock in the neighbourhood,
spreading the GM genes in that way. This is after all how the
cross-fertilisation between the rape and charlock must have occurred in the
first place."

Since charlock seeds can remain in the soil for 20 to 30 years before they
germinate, once GM plants have produced seeds it would be almost impossible
to eliminate them.

Although the government has never conceded that gene transfer was a problem,
it was fear of this that led the French and Greek governments to seek to ban
GM rape.

Emily Diamond, a Friends of the Earth GM researcher, said: "I was shocked
when I saw this paper. This is what we were reassured could not happen - and
yet now it has happened the finding has been hidden away. This is exactly
what the French and Greeks were afraid of when they opposed the introduction
of GM rape."

The findings will now have to be assessed by the government's Advisory
Committee on Releases to the Environment (Acre). The question is whether it
is safe to release GM crops into the UK environment when there are wild
relatives that might become superweeds and pose a serious threat to farm
productivity. This has already occurred in Canada.

The discovery that herbicide-resistant genes have transferred to farm weeds
from GM crops is the second blow to the hopes of bio-tech companies to
introduce their crops into Britain. Following farm scale trials there was
already scientific evidence that herbicide-tolerant oilseed rape and GM
sugar beet were bad for biodiversity because the herbicide used to kill the
weeds around the crops wiped out more wildlife than with conventionally
grown crops. Now this new research, a follow-up on the original trials,
shows that a second undesirable potential result is a race of superweeds.

The findings mirror the Canadian experience with GM crops, which has seen
farmers and the environment plagued with severe problems.

Farmers the world over are always troubled by what they call "volunteers" -
crop plants which grow from seeds spilled from the previous harvest, of
which oilseed rape is probably the greatest offender, Anyone familiar with
the British countryside, or even the verges of motorways, will recognise
thousands of oilseed rape plants growing uninvited amid crops of wheat or
barley, and in great swaths by the roadside where the "small greasy
ballbearings" of seeds have spilled from lorries.

Farmers in Canada soon found that these volunteers were resistant to at
least one herbicide, and became impossible to kill with two or three
applications of different weedkillers after a succession of various GM crops
were grown.

The new plants were dubbed superweeds because they proved resistant to three
herbicides while the crops they were growing among had been genetically
engineered to be resistant to only one.

To stop their farm crops being overwhelmed with superweeds, farmers had to
resort to using older, much stronger varieties of "dirty" herbicide long
since outlawed as seriously damaging to biodiversity.

Q&A: What the discovery means for UK farmers

What's the GM situation in the UK?

No GM crops are currently grown commercially in the UK. Companies who wish
to introduce them face a series of licensing hurdles in Britain and Europe
and interest has waned in recent years amid public opposition.

Other firms have dropped applications in the wake of the government field
scale trials that showed growing two GM varieties - oilseed rape and sugar
beet - was bad for biodiversity.

The EU has approved several GM varieties and the UK government insists that
applications will be considered on a case-by-case basis.

Where are GM crops grown?

Extensively in the wide open spaces of the US, Canada and Argentina. In
Europe, Portugal, France and Germany have all dabbled with GM
insect-resistant maize. Spain plants about 100,000 hectares (250,000 acres)
of it each year for animal feed.

What is a superweed?

Many GM crop varieties are given genes that allow them to resist a specific
herbicide, which farmers can then apply to kill the weeds while allowing the
GM crop to thrive.

Environmental campaigners have long feared that if pollen from the GM crop
fertilised a related weed, it could transfer the resistance and create a
superweed. This "gene transfer" is what appears to have happened at the
field scale trial site. It raises the prospect of farmers who grow some GM
crops being forced to use stronger herbicides on their fields to deal with
the upstart weeds.

Is it a big problem?

Not yet. Farmers in the UK do not grow GM crops commercially. If they did,
then the scale of possible superweed contamination depends on two things:
whether the hybrid superweed can reproduce (many hybrids are sterile) and,
if it could, how well its offspring could compete with other plants.
Herbicide-resistant weeds could potentially grow very well in agricultural
fields where the relevant herbicide is applied. Most experts say superweeds
would be unlikely to sweep across the UK countryside as, without the
herbicide being used to kill their competitors, their GM status offers no
advantage.

Some GM crops, such as maize, have no wild relatives in the UK, making gene
transfer and the creation of a superweed from them impossible.

Is it a surprise?

On one level no, gene flow and hybridisation are as old as plants
themselves. Short of creating sterile male plants, it's simply impossible to
stop crops releasing pollen to fertilise related neighbours. But government
scientists had thought that GM oilseed rape and charlock were too distantly
related for it to occur.

The dangers of hybridisation where it does happen are well documented -
experts from the Dorset centre behind the latest research published a
high-profile paper in 2003 in the US journal Science showing widespread gene
flow from non-GM oilseed rape to wild flowers.

Have superweeds surfaced elsewhere?

Farmers in Canada and Argentina growing GM soya beans have large problems
with herbicide-resistant weeds, though these have arisen through natural
selection and not gene flow through hybridisation. Experiments in Germany
have shown sugar beets genetically modified to resist one herbicide
accidentally acquired the genes to resist another - so called "gene
stacking", which has also been observed in oilseed rape grown in Canada.

[indiamonitor.com]

------------------------------------------
Posted to Phorum via PhorumMail