HIGH FLYERS THINK TANK

Biotechnology and the future of Australian agriculture

The Shine Dome, Canberra, 26 July 2005

Biotechnology: Crops (production)
by Dr Jeff Ellis, Program Leader, CSIRO Plant Industries, Canberra

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I am going to cover that area of crop production and traits which are often referred to as input traits, things that lead to increased yield rather than quality at the end – although many of these input traits also follow through to affect the quality of the crop.

In preparing this talk, I went back and looked at one of the original papers talking about transformation of crops, and I realised it is now 22 years since the first transgenic tobacco plant was made. This paper came out and heralded an era of great promise, both in basic science and in application of this transformation technology to crop improvement. And over those 22 years the advances in our understanding of how plants grow and how they live has been incredibly spectacular. The application of this technology to improved crops through genetic modification has been a little bit slower, but this is only natural, because the application is founded on the basic science.

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Although the basic science gets far more ticks, the application is pretty spectacular as well. At this stage there are 81 million hectares of GM crops grown world-wide, and here I have listed some of the examples of what this technology has been applied to.

Initially, it has been applied to things where you put a single transgene into a plant, and in the future we are moving towards putting in multiple genes, altering pathways and things like that. The success so far – and this has been true in Australia – has been the application of Bt technology to protect cotton from insects, and in the US and South America it has been similar, protecting maize from a number of pathogens including Heliothis and root-attacking organisms and insects.

This, in some cases, has had unexpected positive benefits. For example, in the US, sweet corn and other maize crops which are eaten directly by human and animals have less of the fungal toxins induced by Fusarium. And this is simply due to the fact that the insects are not biting on the maize kernels and making wounds and introducing these toxin-producing pathogens. So that has been an unexpected positive benefit in a production system which is delivering health benefits.

There have been a whole heap of breakthroughs in developing virus resistant plants, although not that many of them have been applied in agriculture. The resistant papaya which we heard about earlier today is one example.

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Herbicide resistant crops are another well-known application in crop production. There have been a lot of advantages to the farmer, to the consumer and even to people who are not living on farms, in terms of the effect of minimum tillage, and in reducing fuel and also erosion. Again unexpected advantages have come out of some of the herbicide resistance in crops. For example, the introduction of herbicide resistant soya bean in the United States has enabled that crop to move further north than it did before, mainly because the two weeks of soil preparation that had been required beforehand – ploughing and that sort of thing – can be eliminated. So you can grow a crop in a shorter time.

I want to concentrate in this talk mainly on pest resistance. Cotton has certainly been the forerunner in Australia in terms of being a pest resistant transgenic crop.

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There are a number of reasons for this success in cotton. One is that Heliothis, the genus of the caterpillar which eats cotton, is a pest of many crops. So there has been a broad interest in trying to control that particular type of pest in a lot of crops. There has been an obvious health and environmental problem that needed to be overcome through conventional control with the use of pesticides. We were at a stage in the cotton industry where we were actually running out of pesticides, due to the evolution of resistance in the Heliothis to those pesticides, so it was really a crunch time for the industry which drove the rapid adoption of these sorts of technologies in the cotton crop.

The other thing which had an influence in terms of society's acceptance is that cotton was a non-food crop. On this slide I say 'non-food (sort of)' because we do actually consume the oil produced from these transgenic crops, and also some of the material does enter the food chain through animal feed. But people have not actually thought about that too much.

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One of the important things I wanted to mention in the success of controlling insects in cotton by using Bt technology is the Bollguard II cotton. What that does is to take two different Bt genes and stack them together. This has a great advantage for the industry, in that it makes that sort of control of the insect much more durable. So if you make the investment, you have some confidence that that protection is going to last a significant length of time.

The reason it does that is that the two genes have independent action. So what has been done is to introduce a double line of defence. That then makes it more difficult for the Heliothis organism to evolve the necessary two independent routes to resistance towards that insecticide.

However, there is at present one disadvantage for the breeder in this technology. The genes happen to be on two different chromosomes, and the rules of genetics mean that those genes segregate randomly. When the breeder takes one variety and wants to make an improved variety through crossing, the difficulty is to select for those genes to be together in the new variety. That problem is something which can be overcome by putting in the extra breeding effort, but there would be great advantage if we could actually put those two resistance genes onto the same DNA molecule so that they would be linked in the breeding process.

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That brings me to wheat, the crop which I work on. At present in Australia there is no transgenic wheat. I have listed here a number of reasons for that.

There is no single specialised pathogen or pest, like Heliothis, which is industry-wide. (I am going to talk about rust, which is getting close to that position.) There has been no real crunch-time problem like the one the cotton industry was facing. And we have got, to a large extent, fairly adequate controls for a lot of the pest and pathogen problems that the wheat industry faces, although there is still a lot of room for improvement in those controls.

The community has been very concerned about using genetic modification to improve food crops like wheat, and in effect the wheat industry is a fairly conservative industry, particularly in places like the United States. Cotton growers and the corn industry have been very rapid to embrace new technology, but the wheat industry in the United States has been very conservative and they have rejected things like Roundup Ready wheat. Although many of the farmers did in fact want those products to be introduced, the industry managers rejected that.

One of the other problems is that biotechnology can be quite expensive and that in crops like wheat there is often a low dollar return from a crop, so the opportunities to recover investment can be smaller.

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As I said, maybe an equivalent industry-wide problem in cereal growing – wheat and barley – is the fungal diseases caused by rust pathogens. These are presently controlled by naturally occurring genes called rust resistance genes, and many of these genes are actually sourced outside the wheat species and brought in from grass relatives, some of which are wild weeds.

The problem with this source of resistance can often be that these genes come in with what we can refer to as 'genetic baggage' – that is, other genes which are linked to the resistance genes and which affect quality and yield. So many of the genes, although highly effective in controlling the rust pathogen, can't be used because they have these detrimental effects.

And, similar to the two unlinked Bt genes in cotton, many of the rust resistance genes that we use are inherited independently, so bringing these things together and stacking them to get this durability of resistance becomes a problem to the breeder who is dealing with many different genes at the same time.

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The GM solution is really a better one for this problem in wheat. 'Pure' resistance genes can be cloned, the baggage can be left behind, these genes can be introduced into wheat through transgenic mechanisms, they can be stacked several genes at a time, and this is durable to pathogen evolution so the resistance will last much longer. And the genes do stay together in this particular case, as I have illustrated with these three stem rust resistance genes, because they are put together on a single DNA molecule. So essentially they segregate as a unit.

This is the area that I am working on at present, and it is the area that Craig Cormick referred to earlier on as being discussed in the meeting that we had last week. One of the problems in this area is that these genes are still difficult to clone. We have made great advances with Sr31 but the others are still in the future. Nevertheless, this is where we intend to head in the future.

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So why aren't we more advanced in the GM application in crops? Most of this work depends on basic science discoveries. Bt in cotton and the other crops has had a long 'conventional history'. It wasn't discovered just yesterday; people had been working on that particular protein for many years before GM technologies came in.

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The high cost of research and development is always associated with these sorts of discoveries and the applications, and some costs come in in meeting the regulatory and registration hurdles. For example, if we wanted to introduce a new Bt gene in Australia, there would be considerable costs incurred in that. Really, only the big problems in big industries can be tackled – economic decisions come into the question.

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So why aren't we more advanced in the wheat industry? We have difficult problems and a knowledge vacuum. What I mean by that is that we really do need to invest more in the basic research.

A lot of people haven't accepted this sort of technology, and in some cases they have countered our work with outright lies. This has tended to cause what I refer as poisoning of the funding waterhole. Even GRDC sometimes hold funds back because they say, 'You're offering a transgenic solution. We're not going to be able to commercialise that in the near future.'

I think what we really need for the future is increased political and commercial courage to push forward a lot of these new technologies and also to support the basic research which is necessary to subtend the application of these new technologies in the future.