Genetically modified (GM) crops: the wheat from the chaff

VOICEOVER
Welcome to Melbourne University Up Close, a fortnightly podcast of research, personalities, and cultural offerings of the University of Melbourne, Australia. Up Close is available on the web at upclose.unimelb.edu.au That's upclose.u-n-i-m-e-l-b.edu.au.

SHANE HUNTINGTON
Hello and welcome to Up Close, coming to you from Melbourne University, Australia. I'm Dr Shane Huntington and today's topic is 'The Realities and Myths of GM Crops'. Most of us have been exposed to the at-times furious debate over genetically modified food and its production. GM has been around as a developing technology and a contentious topic for a couple of decades now. But with a growing global population inhabiting an increasingly fragile planet there is a critical need to optimise our farming practices and maintain our supply of nutritious crops without further impacting existing ecosystems. In recent years, genetic modification of certain crops has led to substantial improvements in yield and pest resistance. Take up of GM crops by farmers has grown tremendously in many parts of the world. Most noticeably, Europe, Japan and North America. There are also those who argue for great caution in implementing GM crops, with some against their use entirely. To help us extend the discussion today on GM crops, we are joined by Prof Rick Roush, an internationally eminent researcher in weed and pest management. As it happens, Rick is also the Dean of the Faculty of Land and Food Resources here at the University of Melbourne, Australia. Welcome to Up Close, Rick.

RICK ROUSH
Thank you, Shane.

SHANE HUNTINGTON
Now, I thought we'd just start by looking at your journey, which is an interesting one. You started off as a geneticist, then you became an entomologist and now you are an advocate for GM research and looking at the effects of it. Tell us about that story, it's quite a pathway.

RICK ROUSH
Actually, I was a genetics major at the University of California, Davis. And one summer, I stopped by the local community library which had a table of controversial books. And one of the ones that was on there was Rachel Carson's Silent Spring. Which I hadn't read before. And I picked it up and consumed it in a couple of days. And decided 'man, this problem with pesticides is really something, I want to do something about this'. So I changed my major to entomology, the study of insects. And, in fact, the very first class I took was in biological control. And that set me on the course of looking at these things. And as I was taking various classes in entomology I gradually realised that genetics was a really key area in dealing with a lot of insect pest-management problems. And, cotton was also a crop of key importance. And that eventually led me to working on genetically modified crops. Because in the late 1980s it became clear that people were looking to put genes into cotton plants in particular to protect them against the attack of insects. And this had potential not only to select for resistance in the pests, which was a thing that really concerned me as a geneticist, but also there was tremendous potential to dramatically reduce the amount of pesticide use in cotton. Through the 1970s and into the early 1980s something like 49% of all the insecticide used in the world was just on cotton. So, if you were an entomologist, inspired by Rachel Carson to work on reducing pesticide use, cotton was the crop you wanted to be into. Cotton was one of the first places where the development GM crops came along, and that was a very attractive thing to try to get to the bottom of. What was going on? Was there anything valuable in it in the long term?

SHANE HUNTINGTON
Now, I think what we might do is just take a bit of a step back, because people don't see traditional farming as involving genetic modification at all. I think there is a view that we should have of this farming over millennia doing exactly that. Tell us your perspective on this sort of version of farming.

RICK ROUSH
Right. Well, most of the things we eat as crops have been domesticated really, over the last six to ten thousand years. And the ancestors to these crops wouldn't be anything like we recognise now. So you'd have things like wild radish, which is sort of a relative of cabbages and broccoli and so forth. If you'd eat a leaf of a wild radish plant you'd be struck how bitter it is. And that's what the ancestor plants were for crops like cabbages, Brussels sprouts and broccoli and so forth. So, people, they had to select these crops to get rid of a lot of these nasty compounds that the plants make. Apparently, to stop herbivores likes us, from eating them. So, we get rid of a lot of those things in the process of domestication. We've also made plants that have larger seeds, larger fruits. Seeds that don't fall on the ground but are retained by the plants to facilitate harvesting. So, enormous changes have occurred in all these crops over time that have been done by human breeding. A lot of times in the GM debate people say, 'well there's something unnatural about these genetically modified crops.' Well, the fact is, everything we eat is pretty unnatural. And if you took the view that the foods that are not genetically modified are the ones that we are meant to eat, the only way you could argue that is to assume that somehow these plants were put on the earth just for our consumption. Evolutionary biologists show that is not what happened. They've evolved to defend themselves and to reproduce. And just as they protect themselves against the feeding from insects and cows and so forth, they have protected themselves against by feeding humans. And it is only our selection of these plants over the last several thousand years that it has actually made them palatable to us and actually very productive for our use.

SHANE HUNTINGTON
Also, the environmental conditions, I mean, we grow crops in locations where they were never evolved to be in.

RICK ROUSH
Absolutely. And one of the most dramatic examples of this is corn, which originates from a small grass called teosinte. There seem to be five major genetic changes that were wrought in the development of corn, roughly 5,000 years ago by Mizo-American farmers who turned it into a crop that now may be nine feet tall, three metres tall. Originally the plant had just two rows of kernels, now it has more than twenty and a giant seed head. Instead of corn being grown just in small areas of southern Mexico and so forth, is grown in southern Canada, way outside its range, well beyond its seeds could survive the winter. It is a major crop in Africa, it is a major crop in China. Again, in all those places it often pushes the boundaries in terms of drier climatic conditions and cold winters where it could never have grown without the intervention of man planting it every year and indeed selecting for traits that allow it to survive under conditions that are far removed from where it evolved naturally.

SHANE HUNTINGTON
We are going to get onto genetically modified crops in a moment, but I'm trying to get a feel for the comparison in terms of change. If you were sitting, 2,000 years ago, and you had all the knowledge that you have today about the ability to make genetic modification and you could see how far in 2,000 years you needed to change this crop, how would that degree of change compare to the amount of change we are initiating now with GM crops?

RICK ROUSH
The vast majority of changes in the crops in the overall germ plasma crop has occurred over the last several thousand years. And indeed, when people are looking to do genetic modification for crops, they're looking to change just a couple of traits. In fact, as people do these changes, they're still retaining the vast majority of existing varieties. I mean, one concern people have had is, we do genetic modification we greatly narrow the genetic base of the crop !V which is a really serious issue !V in the case of genetically modified crops, that is not what is happening. Because everybody who is involved in the cropping process realises that the vast majority of the agronomic value of the crops comes from this long history of breeding. And so, in fact, the genetically modified traits are being put into dozens or hundreds of varieties depending on the crop. Because most of the gain, because most of the value we have in a crop is due to these local differences and this is a result of selections that have occurred over thousands of years. As in the example of corn, if you looked at teosinte, most people would probably not actually recognise that this could possibly be the ancestor of modern corn because it is so different.

SHANE HUNTINGTON
You're listening to Melbourne University Up Close, I'm Dr Shane Huntington, and we're speaking with Prof Rick Roush about GM crops. Let's get to the heart of the matter now. Genetically modified crops !V we'll start with a definition. What exactly does this mean? Because it covers a wide area of change.

RICK ROUSH
Sure. Some people would argue that all the crops we have are genetically modified. But most people, when they start to get into thinking about this as a controversy, are really concerned with things that might more properly be called transgenic crops, that is to say they involve trans-genes. Where genes have been moved from one plant or perhaps bacterium into a major crop plant in ways that cross species boundaries that could never have happened even by heroic crossings of people do in the lab. These are really rather distant crosses. To be able to take a gene out of a bacterium like Bacillus thuringiensis, or BT, which is commonly grown and used in organic insecticide to be able to take a few key genes out of those, modify them in particular ways so that they express well in plants and put them into plants that confer insect resistance !V it is a change that is a bit different than people have been able to do over the last 10,000 years. And that, coupled with the fact that there is a perception that these things are driven by multinational companies has really galvanised a lot of public concern about them. Plus, again, part of it, is people are concerned that somehow these are unsafe because they are really unnatural. Really, if you take a long perspective of them, there is no reason to think that they are significantly more unsafe than things we eat all the time. But it is those kinds of issues that really have people concerned.

SHANE HUNTINGTON
Now, when we talk about genes, we're talking about small components of the DNA that is involved in these plants, what parts of the genetic code do we change? How do you go and pick a part and say 'this is the piece we should change'?

RICK ROUSH
Well, in most cases, what has been done so far is that they haven't actually changed any of the genes in the plants. They've added one or two genes. They typically add a gene that has the effect or you're interested in, maybe it is herbicide resistance or insect resistance and attached to that you include another segment of DNA that is called a promoter, that helps to make sure the gene you're interested in actually gets turned on and, eventually turned into protein. In addition, maybe a third gene called a marker !V selective marker, that you would use to help to be able to identify those few cases where the gene was actually taken up in the plant. The key ones have been to introduce resistance to insects, by using a gene modified from the bacterium, Bacillus thuringiensis, that they're the most effective insecticides ever discovered when delivered to the gut of an insect and even then it is very specific. Some would work only against some groups of caterpillars or only a very small class of groups of beetles, for example. So it became possible to introduce that gene to plants and to give that plant some significant resistance to insects. Insect resistant cotton being one of the most prominent and important examples around the world. Another key example is the introduction of a gene to confer resistance to the herbicide glyphosate, which most people would know by its trade name, Round Up. A product from Monsanto and in this case it gets a bit trickier. Round Up acts on an enzyme called EPSPS that is involved in making certain kinds of amino acids, the building blocks of proteins, that plants can grow. And when you treat weeds with Round Up, what it does is it stops the ability of the plants to make these proteins and eventually the plant starves to death and dies. Dies relatively slowly compared to a lot of other herbicides. So what was necessary to make the plants resistant in this case is to add an EPSPS gene to the plant that could not be inhibited by the herbicide. So, when the plant's gene was shut down and wasn't active, this added gene could continue to function in the pathway that makes the amino acids so that the plant could survive the herbicide, could keep growing. One of the first thing it tells you about the gene that has been added is it has to be really similar to the gene whose function it takes over in the plant, otherwise none of this would work or it would die or malfunction. So, the structures have to be very, very similar, and it turns out they are. They're just different in a few key places that means that the plant is less sensitive to the herbicide glysophate and the plant can survive when the surrounding weeds are killed. So, in terms of the area of the world it is planted, those two genetic transformations account for something like 85-90%, maybe higher , of all the transgenic plants that are grown in the world.

SHANE HUNTINGTON
When we change just a few specific genes, how do we go about determining that the outcome will only be what that gene did in isolation?

RICK ROUSH
Sure. What this really does is, it allows you to introduce new genetic variation. But like any other kind of new genetic variation that are added to plants, the plants have to be very carefully checked afterwards. And in fact, transgenic crops get much more intensely checked than plants that go through classical breeding. Extensive feeding studies are done in animals, compositional analyses are done, so after the transformation events are done and we add the gene, that is only the first step, but just as genetic variation it would usually produce several varieties that you'd test in the lab and if they look good in the lab, you'd take them into the field, try to test out which ones have the best properties in terms of yield and quality and you'd carefully check them for all kinds of untoward effects. If the gene you introduced had fallen somewhere close to some place else. But the key thing about transgenic crops, is you're really introducing one gene, whereas if you do any other kind of breeding, you are potentially manipulating hundreds of genes, so, on a scale of concern, when plant breeders start thinking about this, they're much more worried about so-called wide-crosses or the narrow-crosses. Many of our plant varieties have been genetically modified by radiation to increase genetic mutations for selection. That is also, actually, a greater concern to a lot of breeders than transgenesis because it also introduces mutations scattered all through the genome, not just in the places where you might be mostly interested in getting them. So on a scale of the kinds of untoward effects that could possibly happen, genetic engineering transgenic crops are actually at the low end of the scale and yet ironically, they actually get checked much more intensely than any classically bred crops. It comes back to this issue about what is that people think is safe, and a lot of people tend to believe that things we find in the market place already are clearly safe because there is a long history of human use !V what is the evidence for that? These things aren't getting tested. The vast majority of foodstuffs that are on our food shelves go through no rigourous safety assessment, where in contrast every transgenic crop, every new variety of a transgenic crop gets scrutinized by regulatory authorities in several countries, and usually in each country there will be at least 20 scientists looking at the data sets that are available. There is a much higher level of scrutiny.

SHANE HUNTINGTON
Now, we talked a little about the insect resistance, but there are other attributes of importance, for example, the ability to grow various crops in conditions that are extremely harsh, salinity, in Australia, drought conditions, how far can we go, with crops like cotton and so forth, which are water intensive, I mean, what does the future look like for these particular crops?

RICK ROUSH
Right. Well, cotton is a good example of another crop that really comes from Latin America and is now really being grown around the world in various ways and again, it is being grown a lot of times in areas where the winters are too cold and the soils are too wet for cotton to survive on its own. But one of the things that genetic modification really allows us to do !V because crops of all kinds have for a long time been restrained by their evolutionary history !V there is a limit for how far we can carry them. But one of the things that people are doing a lot these days are looking at kinds of plants that exist in very harsh environments and trying to figure out how they survive. In Australia, for example, the department of Primary Industries in Victoria has been looking at a grass, an arctic grass to look and see how it tolerates cold and by analysing that looking to see if there are genes that could be introduced or genes that could be modified in existing plants to give them a little bit greater tolerance to frost. In a lot of areas around the world, because we're pushing the envelope as to where these crops can be grown, we're often growing them in areas that are too cold, have suffered too many droughts for the crops to really survive on their own and under those circumstances even a modest increase in their ability to take frost or drought or salinity would greatly improve the consistency of yield that we get from those plants.

SHANE HUNTINGTON
You're listening to Melbourne University Up Close. I'm Dr Shane Huntington and we are speaking with Prof Rick Roush, about the realities and myths of GM crops. Now Rick, I guess this is a question you may not have an answer to, but what are the disadvantages of GM crops?

RICK ROUSH
Well, there are some GM crops that some people have proposed that have real questions around them. One that I am thinking of that has been looked at in the United States is a grass for golf courses that would be resistant to the herbicide glyphosate and a lot of people are concerned about, 'well, what if this grass gets out in the natural ecosystems?' So, there are some concerns about that. More broadly, the bigger concerns that worry a lot of the scientists are, you know, 'how are we going to be putting such strong selection pressure on insect pests and weeds, that we are going to lose some of the really handy tools that we have.' So, what really got me into looking at genetically modified crops in the first place, was the introduction of crops that would have the BT gene in them and the concerns we had that this could select very strongly for resistance to BT and this might mean that this very useful tool would have a short life. So a number of us have worked devising strategies to try and slow this down. And I think we've been quite successful. In cotton for example, most new insecticides, we'll usually find some resistance to them somewhere in the world usually in the first five or seven years of their use. That is historical, dating back to 1945 with DDT. In contrast, BT has now lasted in the field for something like 11 or 12 years of widespread use without any problems appearing and we think it is because people have adopted a lot of the strategies we've worked out, which include having some of the crops set aside as a so-called refuge where susceptible insects can breed, and in effect dilute any resistant insects might come out of the crop. That's a kind of strategy that we have never really been able to apply before for chemical insecticides. Because we have much greater capacity to see if people are complying with the strategy, by asking where their refuge is and then going and taking a look at it. The other one that is an issue is, again, because glyphosate has such an effective herbicide, it works in a lot of circumstances, has low toxicity in mammals, is generally safe for the environment. So, in favour of the development of a lot of genetically modified crops which means the areas where it is getting used have increased quite enormously. Even in places where we don't have genetically modified crops, we are seeing increases in glysophate resistant weeds. In Australia, in California for example, in quite parallel cases, we've seen the evolution of resistance to glysophate in a weed called annual ryegrass. In places where there are no genetically modified crops being grown, it is just because the herbicide is so effective people have tended to use it over and over again. In both California and Australia, the first places where this resistance turned up was under orchards, where people were spraying three or four times a year for grass control to save moisture and make harvest of the crops easier. So there is a real concern about this. In the case of glysophate, a bit like BT, because it is so safe and effective we have a tendency to overuse it. And all its best features actually become its worst enemy, or our worst enemy in terms of addressing how we manage or slow the evolutionary resistance. So, these are the kinds of concerns that a lot of people working in agriculture have. They're not new, because we have had to deal with these problems of resistance since about 1950. But there are still great challenges that we are faced with. And they require a lot of education of farmers and growers, and probably even consideration of intervention by government authorities to make sure that good sound practices are adopted and used more widely. But there are still these other issues about how would we move these other crops into the field? How do we take a cropping systems approach to how they're used? How do we make sure we're looking at their long-term sustainability? They are real challenges for the scientific community in terms of adopting them. One other area where there is a lot of concern, is really a market concern. People have been concerned about how can you ensure the co-existence of genetically modified or transgenic crops with agriculture where people may not want to use them, for whatever reason? So how can you ensure co-existence between these two? Particularly because in a few of these crops, like canola, the pollen can move some significant distances. For a lot of crops that is not much of an issue. In the United States and in Canada, this actually hasn't been such a big issue, growers have tended to work out arrangements to do this. It is not actually new because historically people have grown crops of different kinds of characteristics and they have had to work out how to do it. So, somebody wants to grow blue corn, for a tortilla chip market, they have to work out how they can grow the blue corn and not have it contaminated by ordinary yellow or white corn growing all around them. People grow particular kinds of barley, malting barleys for beers they have to make sure that it doesn't get contaminated in any way with other kinds of barleys that don't have the same characteristics. We have to work out systems to make sure that all aspects of agriculture conventional, transgenic and organic, have freedom of choice to their own market opportunities.

SHANE HUNTINGTON
And I guess, the public perception of those who benefit most from GM crops, is usually large corporations or these super-sized farms is that the case? Who benefits most from GM crops?

RICK ROUSH
Well, a European study, a group of European economists recently looked at this, and concluded that everywhere the GM crops are being grown around the world farmers are benefiting economically. Even in the early days of GM crops, when BT cotton was first introduced in the United States, a group at Auburn University checked to see where the benefits were and they concluded that US cotton farmers had benefited by about 128 million dollars in terms of reduced costs of insecticide use. So there was 128 million dollars to the cotton growers and about 62 million dollars to Monsanto, the developers of the technology. And across agriculture, this two to one ratio of benefits to the users compared to the purveyors of the technology is apparently fairly typical. In China where BT cotton was introduced, about 97% of the financial benefits go to the growers. This was published in the journal, Science, by a team of American and Chinese agricultural economists. So, around the world, when people look, the main reason why these crops are being adopted and spreading so rapidly is that they really are providing benefits to farmers. There have been billions of kilograms of increased yield, millions of dollars saved. From an environmental standpoint, even though this hasn't necessarily been what has driven the farmers, there have also been enormous advantages in terms of reduced tillage. Because of reduced tillage there is about nine billion kilograms of CO2 not going into the atmosphere every year. About eight billion of that, because reduced tillage keeps carbon in the soil better and another billion kilograms of that CO2 because people are not using fuel to drag ploughs through fields. They are much more energy efficient just to spray a herbicide across the top instead.

SHANE HUNTINGTON
Just, finally, Rick, I guess one of the things that always interests me is that when these things sound so fantastic and we are having such a problem with scientists getting it across to the community, is it a failure of engagement on our part that has enable misinformation to be put around? Or is it just simply we may not be right on this? I mean, what do we need to do in the future to indicate to people that GM crops are appropriate and get their support?

RICK ROUSH
I think it is a failure of engagement. So, on the one hand we have people who are deeply concerned with these issues. Often times because it affects their sense of what modern agriculture should look like. They object to what they see as the industrialization of agriculture, the involvement of multi-national corporations. The perception that this only benefits large farmers, whereas in fact, the reality is that most of the farmers that have benefited have been small farmers. It is a scale and dependent effect. So we've had a lot of groups that have been very aggrieved by this and have had deep concerns about it and on the other hand who is there to oppose them? If Monsanto or some other biotech company to argue about this, people immediately assume that they're not credible. So, the people that would be most credible are the scientists that have no vested interest in this, and frankly, they're too busy doing other things, like getting their research done and teaching their students. So, part of the problem is that the relationship has been very asymmetrical. We've had people who have been very aggrieved and activist about things, and they're highly motivated to argue that this is a bad thing, really to no credible opposition, because scientists have not stepped forward to talk about this more. That is a real challenge. I mean, part of the reason I get very interested in this, from a public standpoint is that it really comes to the heart of 'what's the role of scientists in society and how do we affect things?' And just as we can find people who will argue that HIV doesn't cause AIDS or that the Holocaust didn't exist, we can find people who have strong views that this is a terrible thing, contrary to what all the facts might say.

SHANE HUNTINGTON
It's certainly a big task ahead of us. Prof Rick Roush, thank you very much for being our guest on Up Close today.

RICK ROUSH
Thank you, Shane.

SHANE HUNTINGTON
Relevant links, a full transcript and more information on this episode can be found on our website, at upclose.unimelb.edu.au. We also invite you to leave your comments or feedback on this or any other episode on Up Close, simply click on the add new comments link at the bottom of the episode page. Melbourne University Up Close is brought to you by the Marketing and Communications Division in association with Asia Institute of the University of Melbourne, Australia. Our producers for this episode were Kelvin Param and Eric van Bemmel. Audio recording by Dean Collette. Theme music performed by Sergio Ercole. Melbourne University Up Close is created by Eric van Bemmel and Kelvin Param. I'm Dr Shane Huntington. Until next time, thank you for joining us. Goodbye.

VOICEOVER
You've been listening to Melbourne University Up Close, a fortnightly podcast of research, personalities and cultural offerings of the University of Melbourne, Australia. Up Close is available on the web at upclose.unimelb.edu.au, that's upclose.u-n-i-m-e-l-b.edu.au. Copyright 2007 University of Melbourne.