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July 25, 2005

GM Cross Breeding?

Reports that GM plants are cross breeding with wild weeds and thus producing herbicide resistant forms. That’s what the researchers are saying:

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.

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.

There is one dissident voice:

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".

So some are calling it gene transfer and at least one is saying this is simply the traditional emergence of  resistance.

Who’s right? Under this blog’s outsourcing policy I think we’ll have to see what the Bunny has to say on the matter, this is his field.

July 25, 2005 in Environmentalism | Permalink


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How could this be? Mr Blair's govt promised us it could not happen because a strip two metres wide would be left around all GM crops. Derisive snort.

Posted by: dearieme | Jul 25, 2005 10:07:36 AM

I will not eat food containing DNA!


Posted by: Rob Read | Jul 25, 2005 12:53:47 PM

We need more information on this. Dr Johnson is correct in as use of any sort of 'cide will exert a selective pressure on the target organism, eventually producing an immune strain, provided at least some individuals survive to breed. The existence of such a strain of weed in amongst a related GM crop tells us nothing about why it survived. It may be produced by gene transfer via virus, or via a vicious process of selection driven by heavy use of herbicide. Cross breeding is unlikely, unless intermediate varieties can be identified.

What matters is what has confered the immunity. If, for instance, the rape crop is immune as a result of the poison being metabolised once absorbed and the charlock is immune because the poison is either not absorbed, or excreted following absorbtion, then no gene transfer has happened. It is only if they are immune for precislely the same reason, and the one DNA sequence appears in both genomes, that we can claim with reasonable certainty that gene transfer has occured.

Posted by: Chris Harper | Jul 25, 2005 1:14:14 PM

"this is his field."

Tim, was this a deliberate pun?

Posted by: Chris harper | Jul 25, 2005 2:42:20 PM

You have to read pretty far into the article to find out that the weed was (apparently) sterile. As for the crossbreeding versus evolution argument, it seems obvious that the weed's DNA should furnish the answer as to which is responsible.

Posted by: Brainster | Jul 25, 2005 9:06:35 PM

Rob, if the EU get's is way, i will not be able to eat food with DNA, let alone modified DNA.

Posted by: ivan | Jul 25, 2005 9:58:39 PM