Potental GM crop problems?

[IllegalArgument]

I stumbled across this article about the problems with GM crops.
http://www.guardian.co.uk/gmdebate/Story/0,2763,1535428,00.html

Appearently, some of the genetic traits are getting passed on to nearby plants, creating "superweeds".

Another, issue has been GM crops, migrating into normal crops, ie GM rape seed growing in the middle of wheat fields. Unfortuately, the farmers can't remove the GM rape seed because it's resistent to herbicides. So, it becomes another "superweed", fighting the wheat for nutrients.

Discuss?

 

[drkitten]

I stumbled across this article about the problems with GM crops.
http://www.guardian.co.uk/gmdebate/Story/0,2763,1535428,00.html

[...]

Discuss?

The Guardian lacks a certain amount of credibility as a paper of record, and this article does nothing to dispel that.

The original finding is credited to five unnamed scientists; the paper quotes only a single scientist (Dr Brian Johnson), whose political affiliations appear to be rather questionable. (English Nature does not appear to have substantial scientific expertise; they are mostly a conservation group.) The primary fact that seems to be under dispute is whether the hybrid plant is fertile, to which Dr Johnson's comment that it has large flowers does not appear to be relevant:

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.

Of course, none of this actually demonstrates the Guardian article is actually false. I merely want to see a better, more reliable witness before I believe a word of it.

 

[IllegalArgument]

I almost didn't post it because it was the Guardian, but I was hoping someone had a better link.

 

[RichardR]

The bit that caught my eye was this:

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.

So these weeds had developed a resistance to three weedkillers. Possible, but did this happen because of the original engineered resistance to one weedkiller, or would it have developed anyway?

 

[Deetee]

Guardian:

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.

Well I cannot find anything on the web site, anywhere.
Has it been pulled?
http://www.ceh.ac.uk/index.html

 

[RichardR]

The BBC has a slightly less critical article

But researchers said their work showed the chances of such transfer were slim.

What is more, they argued, the study reinforced the view that the environmental impact was negligible.

"Herbicide-tolerant weeds tend to under-perform compared with wild type, so unless all its competitors have been sprayed out with the same herbicide, it won't thrive," commented Dr Les Firbank, who led the consortium of scientists on the recent UK Farm-Scale Evaluations (FSEs) of genetically modified plants.

"There's lots of evidence for that," he told the BBC News website.

(Snip)

DNA analysis on a leaf sample confirmed the gene trait from the engineered oilseed rape was present, but when the researchers returned the following year to the same field they could find no herbicide tolerance in seedlings of the charlocks growing there.

 

[mummymonkey]

DNA analysis on a leaf sample confirmed the gene trait from the engineered oilseed rape was present, but when the researchers returned the following year to the same field they could find no herbicide tolerance in seedlings of the charlocks growing there.

Sounds like these 'superweeds' were anything but. If they even existed.

 

[tracer]

Appearently, some of the genetic traits are getting passed on to nearby plants, creating "superweeds".

How on earth could this happen?

The nearby plants that are supposedly getting these newly-engineered genetic traits passed on to them are charlock weeds, which are so distantly related to the genetically-modified rapeseed plants as to be laughable. If by some miracle a cross-breed did occur, it would likely look nothing like a charlock or a rapeseed plant.

I'm siding with the commentator who guessed that the herbicide-resistant charlock evolved due to all the herbicide being used against it, not due to some magical genetic drift of the engineered herbicide-resistance gene.

 

[Floyt]

It's too bad that these non-technical articles seem to be the only accessible source on the net right now.
Judging from the evidence given in these two, I'd indeed say that there is no good indication that a gene transfer occurred (they comment on the "unlikeliness" of this happening, but neglect to even give an indication how it DID happen!). My guess, unless better evidence is presented, would be an independent development of resistance.
(Actually the BBC article makes the same kind of shaky inference, about another case.)

I also think this bit of "substantiation" for the fertility claim is quite weak:

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."

... so using the weakly established claim for cross-fertilization as a basis for a further claim, about the charlock's fertility. This is not good reasoning IMO.

A bit distressing, since these shakily substantiated scares poison the well for other research about the effect of GM plants in ecosystems, which is sorely needed. Things are anything but clear-cut at this point

---

edited to add:

btw...

posted by tracer

The nearby plants that are supposedly getting these newly-engineered genetic traits passed on to them are charlock weeds, which are so distantly related to the genetically-modified rapeseed plants as to be laughable. If by some miracle a cross-breed did occur, it would likely look nothing like a charlock or a rapeseed plant.

As far as I can glean it from my books, charlock and rapeseed are about as distantly related as plums and apricots, the union of which has given us the lovely nectarine. So I don't think a gene transfer is as totally out of the question as you imply.

 

[RichardR]

I'm siding with the commentator who guessed that the herbicide-resistant charlock evolved due to all the herbicide being used against it, not due to some magical genetic drift of the engineered herbicide-resistance gene.

Quite possible. There was a report last year of Roundup ready Cocaine plants - Coca plants that were being sprayed with glyphosate (Roundup) as part of the "war on drugs" had developed a resistance. An examination of the genes apparently showed it had not been engineered in - it must have evolved. Of course, the farmers, once they found out, had been breeding with the roundup ready plants.

 

[David Carroll]

Floyt wrote:

As far as I can glean it from my books, charlock and rapeseed are about as distantly related as plums and apricots, the union of which has given us the lovely nectarine. So I don't think a gene transfer is as totally out of the question as you imply.

Not quite accurate. Plums and apricots are both members of the genus Prunus whereas Rapeseed is Brassica and Charlock is Sinapis. Hybridization at the species level is quite common.

 

[RichardR]

It's too bad that these non-technical articles seem to be the only accessible source on the net right now.

Found it: the study.

 

[Floyt]

Aha! Thanks for digging that up!

So when herbicide tolerance was found in charlock plants, they actually did a PCR to make sure the reason was the identical gene as in the rapeseed. That removes on objection.
On the other hand, I can't find any clarification in the article about whether the gene tested for could be readily discerned from a naturally evolved resistance gene, which has been the main criticism here.
The term they use is "gene construct (bar)", which has the ring of something discernibly engineered... but no further details are provided. Hmmm

 

[RichardR]

Aha! Thanks for digging that up!

So when herbicide tolerance was found in charlock plants, they actually did a PCR to make sure the reason was the identical gene as in the rapeseed. That removes on objection.
On the other hand, I can't find any clarification in the article about whether the gene tested for could be readily discerned from a naturally evolved resistance gene, which has been the main criticism here.
The term they use is "gene construct (bar)", which has the ring of something discernibly engineered... but no further details are provided. Hmmm

Are you saying it could have evolved naturally? That it isn't necessarily a gene transfer from the GM crop?

If so, isn't that rather a fundamental flaw in the testing?

 

[Floyt]

Well, that's what I thought. It's not as if such things weren't on record - actually, naturally evolving herbicide resistance has long been an argument against constant low-level herbicide application. If in this study they were able to definitely keep "engineered" vs "natural" resistance genes apart, IMO their results seem to stand. If not, things look shaky. Can't find any discussion of that aspect in the article, though.

 

[RichardR]

Well, that's what I thought. It's not as if such things weren't on record - actually, naturally evolving herbicide resistance has long been an argument against constant low-level herbicide application. If in this study they were able to definitely keep "engineered" vs "natural" resistance genes apart, IMO their results seem to stand. If not, things look shaky. Can't find any discussion of that aspect in the article, though.

Seems rather sloppy. Especially since (according to the “roundup ready cocaine” article I linked), it’s possible to tell if the resistance is engineered or if it has evolved.

Have you heard of the resistance to more than one herbicide? From the Guardian article:

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.
…
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.

How would that even be possible?

 

[Floyt]

quote:
--------------------------------------------------------------------------------
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.
…
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.
--------------------------------------------------------------------------------



How would that even be possible?

Huh. Beats me. I never heard of that. Maybe the loci for the two resistance types were so similar that both might crop up in a batch of modified DNA that was supposed to contain only one type?

How the "superweeds" supposedly managed that, I have no idea, though.

 

[Beausoleil]

How on earth could this happen?

The nearby plants that are supposedly getting these newly-engineered genetic traits passed on to them are charlock weeds, which are so distantly related to the genetically-modified rapeseed plants as to be laughable. If by some miracle a cross-breed did occur, it would likely look nothing like a charlock or a rapeseed plant.

I'm siding with the commentator who guessed that the herbicide-resistant charlock evolved due to all the herbicide being used against it, not due to some magical genetic drift of the engineered herbicide-resistance gene.

Experiments like this are done to ensure that our current understanding of what can happen is correct. We already know that such transfer is unlikely on theoretical grounds, but is the theory sufficient to cover real world applications of the technology.

It's hard to tell from what's online. But if the theory being tested is used to require alternative explanations for results it doesn't predict, the theory isn't being tested.