Debating The Potential Danger Of Transgenic Weeds

If a genetically engineered crop crosses with a wild relative, could a more robust, herbicide-and-insect-resistant weed result? Biologist Nina Fedoroff and ecologist Allison Snow discuss past instances of genetically engineered plants migrating beyond farm borders, and whether that poses a threat to ecosystems.

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IRA FLATOW, host:

Last Friday we talked to Dr. Nina Fedoroff, the new president of the American Association for the Advancement of Science, about some of her goals for the AAAS. And towards the end of the interview, we ended up talking about genetically engineered crops, an area of Dr. Fedoroff's expertise. And that exchange, I'll tell you, generated a storm of letters and comments on our website, urging us to do a follow-up segment. And let me just replay a brief clip from last week's show.

(Soundbite of archived recording)

FLATOW: But there are cases where these crops have, so to speak, leaked out of the farms where they were started, or the fields, and gone to other places no one thought they would go to.

Dr. NINA FEDOROFF (King Abdullah University of Science and Technology): No.

FLATOW: There are no cases of that?

Dr. FEDOROFF: No.

FLATOW: I beg to differ.

(Soundbite of laughter)

Dr. FEDOROFF: Crops don't leak out. We have domesticated crops over a very long period of time, like tens of thousands of years. And crops get - seeds get carried. Sometimes, if they're very small seeds, they get scattered off trucks. Pollen travels.

FLATOW: That's not leaking. That's what I would call leaking out.

Dr. FEDOROFF: But they're still the same plants, and they're domesticated plants. They're not wild plants. So you can talk about it as leaking, but I don't know what that helps. It doesn't - it's not like agricultural plants take over the - they're not weeds. They're not invasive weeds. They're highly domesticated crop plants.

FLATOW: Mm-hmm.

Dr. FEDOROFF: So they - in some cases, if you've got last year's crop that didn't - that comes up in the field when you don't want it to come up, it's called a volunteer. It's a management problem. It's not an ecological problem.

FLATOW: And that's what our conversation was last week about transgenic seeds and pollen leaking out, as they call it, beyond the plant itself and maybe creating unintended problems. Could there possibly be crosses that the pollen makes with the wild relatives in creating something different, maybe a new kind of super weed?

Joining me to discuss these are - Nina Fedoroff is back. She's a visiting professor at King Abdullah University in Saudi Arabia. And Evan Pugh, professor of biology at Penn State. Welcome back to SCIENCE FRIDAY, Dr. Fedoroff.

Dr. FEDOROFF: Delighted to be back.

FLATOW: Also with us is Allison Snow. She's a plant ecologist and biology professor at the Ohio State University in Columbus. Welcome back to SCIENCE FRIDAY, Dr. Snow.

Dr. ALLISON SNOW (Ohio State University): Thank you. Great to be here.

FLATOW: Well, you heard that quote, I'm hoping. What are your thoughts on this? Are there any examples of crops that maybe didn't behave or leaked out, as I call them?

Dr. SNOW: Well, I think you were right to say that genes from GM crops have leaked out in the pollen and the seeds, and just the fact that the genes have moved have caused some problems. But I think what you're wanting to focus on now is what kind of weedy problems might result from that.

And as a typical scientist, I'm going to say it depends. There have been some cases of weeds acquiring traits from genetically modified crops that are causing some problems. One of the most well-known ones is canola, which is one of the few crops that's actually genetically engineered. There's soybean, corn, cotton and canola. And canola itself can be a weed, both as a volunteer, as Dr. Fedoroff mentioned, in the same field, but it can also spread along roadsides.

And there are reports of canola with genetically modified herbicide resistance spreading along roadsides and into lots of areas, including farmers' fields, and it is considered a weed problem. It's one of the top 20 weeds in Canada.

FLATOW: Tell us about your work on sunflowers. Didn't you find that insect-resistant genes in genetically modified sunflowers might be a potential problem if it got into wild sunflowers?

Dr. SNOW: We did find some evidence for that, yes. We did some experiments and found that a gene for insect resistance in wild sunflower can give these weeds a big boost in the number of seeds that they make, but that has not been commercialized, so it hasn't actually happened yet.

And so this is one of the future scenarios that we think about, is what are some traits that could get in to weeds that could cause them to become much more prolific.

FLATOW: Mm-hmm. Nina, any thoughts from last week?

Dr. FEDOROFF: Well, I think what Allison said is absolutely correct. It is a management problem. She spoke about, as I had mentioned in my segment, that some seeds can fall off of trucks and so forth and get into farmer's fields. Those, again, are management problems in the farmer's field. They're not an ecological problem.

FLATOW: Allison Snow, don't you agree it's just a management problem?

Dr. SNOW: To an extent, I agree. But when you manage weeds, you have to use different types of herbicides, and Roundup or glyphosate is one of the most ecologically friendly herbicides out there.

So if that doesn't work anymore, farmers in Canada are using a cocktail of herbicides now to control the volunteer canola, including things like 2,4-D. So these management problems can translate into environmental problems in some cases.

Dr. FEDOROFF: I'd like to make a point here that this is not a problem that has anything to do with this particular form of genetic modification. It was a problem with herbicide tolerance long before crops were modified to be herbicide tolerant by molecular techniques. So this is an old problem. It's an old management problem. Weeds do become resistant to herbicides, and it needs to be managed with multiple herbicides.

FLATOW: Dr. Snow?

(Soundbite of laughter)

Dr. SNOW: True. But I think people have called glyphosate - weed scientists consider - I'm not a weed scientist. I'm an ecologist. But weed scientists call glyphosate the herbicide of the century. We're not going to have another herbicide like that. So for that herbicide to stop working is going to cause a lot of economic and environmental problems.

FLATOW: That's Roundup, right?

Dr. SNOW: Roundup, yeah.

Dr. FEDOROFF: And that's a point, but it's hard to see how avoiding herbicide - glyphosate-tolerant plants - is going to solve the problem.

Dr. SNOW: Hmm. I'm not sure what you mean by that.

Dr. FEDOROFF: Well, you say - you focus on the fact that it's a problem, but it is a problem for farmers, and I'm not sure what your implication is when you say it's a problem.

Dr. SNOW: Oh, I'm talking about the case where, say, in California now there is volunteer canola, cereal canola, that people want to get rid of it because it's a weed. And they can't use Roundup anymore and they can't use 2,4-D because it's not allowed. So it just creates more of a headache for weed management.

Dr. FEDOROFF: Right. I think we both agree that that's the case.

FLATOW: So...

Dr. FEDOROFF: But it's not unique to this particular technique for creating - for developing, let's just say tolerance, because that can be done...

FLATOW: Mm-hmm.

Dr. FEDOROFF: ...just by...

Dr. SNOW: Yeah, regular crops can become weedy problems or hybridized with weedy relatives and so can genetically engineered ones. What I find interesting is that there are certain traits that we haven't been able to use in regular crops until we had the techniques of genetic engineering. And these are not in the evolutionary pathway of the wild relatives. So they're actually new traits that are - that we're looking at every year, new traits are being invented.

Dr. FEDOROFF: One of the really remarkably beneficial aspects of genetic engineering is that much of the previous methodology for controlling pests and so forth is through chemicals that affect a very broad spectrum of insects, for example, or fungicides that control fungi. But what we're being able to - we are now able to develop are plants that actually resist those pests or diseases much in the way that we vaccinate people. And that's obviously preferable to using antibiotics, because you can develop antibiotic tolerance, whereas if you vaccinate a person, that person becomes essentially immune to that particular disease.

FLATOW: Let me just jump in and say this is SCIENCE FRIDAY from NPR. Dr. Snow?

Dr. SNOW: Okay. Yeah. I think those are very good points. I just wanted to return to the point that crop genes do get out into the environment, and they do cause problems in some cases. And that because when traits are genetically engineered, we have to pay special attention to the new kinds of traits that may be getting into some of the weed populations.

Some of the crops that we have that don't become weedy are great. We don't have to worry about that. But in the future, when we have genetically engineered grasses and trees and algae, I think it's worth paying attention to all of these questions surrounding the movement of the new transgenes.

Dr. FEDOROFF: Now, one point that I'd like to make and underscore here is that this is not a problem that is unique to genetic - current methods of genetic modification. This kind of problem has always been in agriculture as long as we have created derivatives of wild plants that we don't want to cross with wild plants. So I think that the important thing to focus on is that we need to look at the trait, not at the...

FLATOW: Mm-hmm.

Dr. FEDOROFF: ...method by which it was produced.

FLATOW: But that's what Dr. Snow was saying. A lot of people are worried - and I'll just say this as representing the public - that you're taking genes from organisms that would never breed naturally in the wild with plants and putting them in there.

Dr. FEDOROFF: That is true. But again, let's focus on the fact that a gene is simply an instruction for making a protein. And today we know that proteins do all the work in organisms and they're very closely related. So for example, you have hemoglobin genes and plants have hemoglobin genes. These code for proteins that bind oxygen, the plants use them for very different things than you them for.

But the point I'm making is that all life is quite closely related and uses, translates the same proteins from the given instructions whether you put them in one organism or another.

So the fact that there are isolation, that species can isolated from each other, doesn't mean that it's dangerous to take a gene from one to another. It is not inherently dangerous.

FLATOW: If that gene or that plant finds itself in an organically growing field, then can we consider it organic anymore?

Dr. FEDOROFF: No, that's actually not true because the organic rule allows a certain level of contamination with pollens from other kinds of crops. That's always been a problem with organic farming. It's not a new problem and the rules actually accommodate that.

FLATOW: Dr. Snow, Allison?

Dr. SNOW: Yes. I mean, it's - I think of organic farmers as a group - a major group that would like to prevent transgenes from getting into their crops, as well as many countries feel that way.

But I'd also like to return to the point of all organisms being related because now we have the ability - and I'm sort of playing devil's advocate here, Dr. Fedoroff, that we could put pharmaceutical-producing protein, you know, genes into plants, we can create a lot of genes that go into food plants where we don't really want that in our food.

And I think that's what the public is concerned about, that we have pharmaceutical-producing rice and corn now that's grown under very high security. But you know, those are just some of the other issues in addition to the weed questions that the public is concerned about.

Dr. FEDOROFF: But I think that one shouldn't simply mix all those things together because the stringency with which crops that are producing pharmaceuticals need to be isolated from others depends on the properties of the protein or substance that's being expressed.

Dr. SNOW: Right. And as you said, we need to look at that case by case.

Dr. FEDOROFF: So I think there are regulations that cover all of that, and I think that it's just alarmist to say that any gene is a problem or new genes are a problem or genes from other species are problems. There simply...

FLATOW: But we need to give them some time before we make the final - do we not just need to give them some time before we make a final judgment on any of this?

Dr. FEDORROF: Well, let's - let me say that the European Union just published a report that summarizes 25 years of research on the safety of genetically modified organisms. And their big conclusion is that the organisms modified by molecular techniques are no more risky than(ph) organisms modified by any other technique.

FLATOW: Dr. Snow, I've got 10 seconds. Any rebuttal?

Dr. SNOW: They say - that report is true. They say that they say per se, so they mean like in and of themselves. But I think need we need to look at the larger context, case by case.

FLATOW: All right. And we run out of time. Thank you, Allison Snow and Nina Fedoroff. And thank you all for joining us today and we'll see you next week. I'm Ira Flatow in New York.

Dr. SNOW: Thank you.

FLATOW: Bye-bye.

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