Drought and climate change are major risks to our food security but so are plant pathogens. Professor Mark Gibberd discusses how scientists are combatting the effects of plant pathogens on crop production.
Plant pathogens are just as much of a risk to crop production as the effects of drought or climate change.
In this episode, Professor Mark Gibberd, from the Centre for Crop and Disease Management, explains how scientists are combatting these pathogens to ensure food security now and into the future.
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You can read the full transcript for the episode here.
Jess: This is The Future Of, where experts share their vision of the future and how their work is helping shape it for the better. I'm Jessica Morrison...
David: And I'm David Blayney.
Jess: Plant-based products make up the overwhelming majority of most people's diets. As the world population increases, mitigating the effect of plant pathogens caused by fungal, bacterial or viral infections will be paramount to food supply and security. To discuss this topic further, with us today is Professor Mark Gibberd, Co-Director of the Centre for Crop and Disease Management. Welcome, Mark.
Professor Mark Gibberd: Thank you, Jess. It's a pleasure to be here.
Jess: Firstly, what is food security?
Professor Mark Gibberd: Food security is a term that is used quite generally, but it means essentially that if you have food security, you have sufficient calories and you have sufficient nutrients to ensure that your entire population goes unhungry, that they have everything they need to grow and to thrive. It's a major global issue. Globally, about one in nine people don't have adequate food security. That equates to about 821 million people who are undernourished around the world at the moment. About 22 per cent of children are stunted in their growth in some shape or form and about six or so percent underweight or undernourished. So, it's a major problem globally. It tends to be distributed in different regions. Africa and Southern Asia are probably the key areas, but it can also pop up in times of trouble and strife when food supply, for example, is disrupted through regional conflict.
Jess: How do plant pathogens impact food security? I mean, when we think about food security, people are probably more so thinking about those last few examples that you just gave, but talk to us about the plant pathogens.
Professor Mark Gibberd: You're right, Jess. People tend to think about drought and long-term changes in climate as being risk to food security. And in fact they are: they're major risks. But pathogens are also important because they tend to steal from the edges of production. They can be the difference between having a profitable crop or a crop that provides its optimum yield, or in some cases they can completely destroy a crop and take it out of production. The key there is that pathogens are often an issue for food security when you've actually got really good potential yield. When you've got crops growing in non-drought conditions or where we don't have other environmental influences, pathogens can actually come in and they can really make a very damaging effect. 20 to 30 per cent is not uncommon, and in some cases right up to 80 or even 100 per cent of crop loss.
David: What's being done to combat these pathogens?
Professor Mark Gibberd: Curtin and the GRDC – the Grains Research and Development Corporation – have a major investment here in the Centre for Crop and Disease Management. That centre has a focus on trying to address the role of pathogens in Australian agriculture and we focus on a range of different crops, so cereal crops such as wheat and barley, pulsars, and also canola. We take a number of different approaches: we look at the genetics of the crop, we look at the role of fungicides and we also look at the role of biosecurity.
Jess: Are new technologies making it easier to combat these issues?
Professor Mark Gibberd: Absolutely. And if we take those three examples and we'll start with perhaps the genetics. In our centre here, we will go out and we'll have a good look around the landscape to understand what pathogens are occurring in the landscape, and we collect what's called an 'isolate'. So we'll take a piece of tissue off a wheat plant, for example. It has a disease such as yellow spot, which is one of our common diseases. That disease takes up to about 20 per cent of yield if it's uncontrolled. Now, 20 per cent of yield doesn't sound like lots – it's only one in five, right? But, if you're thinking about your profitability of that crop as being perhaps around 10 to 15 per cent, it can be the difference between making a profit or not making a profit. It's actually a really important difference. And it can take an area or a crop out of production simply because of the economics. And that's where it has the flow-on effect on food security.
Professor Mark Gibberd: But for the genetics, if we look then at those isolates that we collect and bring back to the lab, we purify those, we understand what the genome of that isolate is. We sequence the genome. We can do a lot of comparative genomics to look at the differences of the genome, of the different isolates around the landscape to understand how they differ, and then we can look at how those different genotypes of those isolates impact upon the crop varieties. In the simplest sense, we can take different isolates that are highly pathogenic or not highly pathogenic and where we can screen new germplasm of the host, so the wheat varieties, to see which ones are most affected and which ones aren't. But, we can go a lot deeper than that. We can get right into the biochemistry and the molecular biology to understand what's actually going on when the pathogen starts to invade the leaf tissue of the host – how the host responds to that, whether it's sensitive or whether it has some form of resistance – we can then develop genetic markers based on that, that allow plant breeders to generate better crops for the future.
Jess: If you are finding resistant things in the lab, how does that translate to the farm?
Professor Mark Gibberd: It's a really good question. We are working right from the really detailed part of molecular biology, where we're getting a great understanding of what's going on. But once we understand the process, then we can go and look more broadly at the germplasm that we have in the hosts. We can take what we call 'populations' of different wheat varieties, where we've got crosses between parents that we know are resistant and parents that have less resistance, or we can search for different types of resistance using the types of information that we've generated from the laboratory. And from that, we can create genetic markers that tell us whether or not we can predict that if we cross a wheat variety with another one, there's an opportunity that we might be able to actually generate a much more resistant progeny from that. Those markers are critically important and it's a technology-based approach to crop improvement.
David: And how effective has this been so far?
Professor Mark Gibberd: Very effective. CCDM in its early years has been able to generate genetic markers that allow for the selection of resistance to several of our key pathogens, particularly in the wheat space. There's good examples of where that's been taken up by the industry and we've seen improvements in crop disease resistance from our research and also from the research of others. And we're generating new markers and new outputs for breeding companies in particular at a frequent level. That information then gets utilised by the breeding companies, but it can still take several years for those new varieties to appear and be available to farmers.
Jess: Is there a global approach being taken to these issues? Can we learn something from places around the world?
Professor Mark Gibberd: Absolutely. And the science in particular that underpins the crop improvement is certainly a global effort. We've several major research groups that we partner with and that allows us to make sure we articulate our research findings with theirs, allowing us to progress more rapidly and we can achieve better outcomes.
David: Tell us about fungicides.
Professor Mark Gibberd: Fungicides are one of the major control options that we have for disease. I've already spoken about the potential for genetic improvement of the host and certainly that's the long-term goal. Wherever we possibly can, we generate new crop varieties that have higher levels of resistance to fungal pathogens, but in the interim period where that new germplasm is not available, what we try to do is manage diseases using fungicides. Fungicides are a bit like antibiotics in humans. When we get sick and we go to the doctor, the doctor might prescribe us an antibiotic to help with that particular illness. But you're probably aware that when it comes to antibiotics, we hear about antibiotic resistance where those antibiotics aren't working as well as they used to in the past. That's exactly what happens in fungicides as well. So in the Centre for Crop and Disease Management, we've got a long track record of not only discovering sources or new cases of fungicide resistance, but also being able to investigate and quantify exactly what's going on when that occurs, so that we can then provide information on a more sustainable use for fungicides into the future. But it is an emerging and significant problem for agriculture in just the same way it is for human health, when we come to antibiotics – in the same way it is for animals as well. This is an area where we're quite globally significant in our research. We've got great capacity to go out and detect fungicide resistance. We've got a great understanding of what happens when it occurs. And we're certainly working very closely with industry now to try and develop management solutions for in-field practice that help to deal with circumstances where we've detected fungicide resistance occurring in paddocks.
David: So, we've got genetics and we've got fungicides; how else are we controlling these pathogens?
Professor Mark Gibberd: The other area for us that's of key importance is around biosecurity. And it's about understanding the way in which diseases change, either through new introductions of diseases into Australia, which unfortunately still occur and we've got a long track record of diseases that have come into Australia over time. Most of our diseases have been imported over time, through human activity and sometimes you're coming in with weather and airborne diseases, but mostly through human movement or movement of products or activities. But there are some new diseases that we have and there's new diseases that we are very concerned about in the near future. We keep a constant eye out for those and we've got some really good molecular biology tools to be able to go out and screen to ensure we are able to detect when we have those diseases or if we don't have those diseases. And that's a really important tool for us. The other thing that's really significant, and this is something that the CCM also has fantastic expertise in, is actually monitoring the changes that occur in diseases when they occur in the landscape.
Professor Mark Gibberd: So, diseases that have been introduced to Australia and have been here for maybe the last 20 years or so don't stay the same. They change. So fungicide resistance is one example of that change. But they also change in their pathogenicity and their behaviour. They're quite adaptive. So it's an arms race between how the pathogen can change and how it evolves because of the pressures that are placed on it through agriculture, whether they be fungicides or just different crop varieties or different farming practices and what we can do to try and get better germplasm, better genetics in that case in the host, or better fungicide use so that we can help alleviate the pressure of those diseases.
Jess: What work needs to be done to prepare the grains industry for the future?
Professor Mark Gibberd: The most important challenges for the grains industry in our part of the world, is really around ensuring the economic sustainability of practice. People often talk about sustainability in terms of the impacts on the environment, for example, and that's absolutely important. So please don't interpret that I'm not putting significant importance on that, but the enabler that enables the industry to ensure that it has a sustainable production relates to its profitability. So, solid, profitable, low-impact agriculture is what we're seeking to achieve. If we look globally, we've got about 0.2 of a hectare of land available for agricultural production per person, around the world. In Australia it's probably about 1.6–1.8 hectares. But, if you think of that, that's 2000 square metres per person of productive land, globally. We have to do absolutely everything we can to sustain that land to ensure that it remains productive in the future. Now, diseases are part of it. As I mentioned, that's often what steals from around the edges or steals from the potential of the crop within a year. But so too are a whole range of other things like climate change, land degradation, pressure from housing or roads and other infrastructure and so on. But at 0.2 hectares of land per person, there's not a lot of room to move, okay? And we really need to be on the front foot of this. The only way that you can ensure that you are really keeping your agriculture as current as possible using new technologies and advancing wherever possible is to ensure that it's also profitable. And that's where economics comes to play.
David: And how are we doing at protecting that 0.2 hectares of land?
Professor Mark Gibberd: We're not doing real well and, certainly, the amount of land per person globally is going back because population obviously is increasing, but also we're actually losing arable land, globally. Now, obviously climate change is a major driver of that. It's very, very important in Australia because a lot of our production tends to be hitting towards the marginal edges in terms of available rainfall and available water for crops. And as we see changes in rainfall and changes in water availability that is going to drive changes in land use and then practice. In the first instance where land is not ideal for crop production, it tends to fall back into pasture production or animal production, which is also very important for food supply. But these are drivers that are long-term issues and you can certainly see them coming. Climate change, everybody, is absolutely real. It's measurable and it has a significant impact on agriculture. It has flow-on effects as well. So while we can look at rainfall and we can look at crop productivity, and other things such as that, we also know that climate change has other impacts and pathogens is one of those. So, we see potential changes in the areas where pathogens are likely to have impact. We see potential changes in their severity based upon climate change as well.
David: You mentioned profitability. Some countries have quite heavy subsidies on their agricultural sector, whereas over here we emphasise research and development more. What's being done in Australia to ensure the industry's economically sustainable?
Professor Mark Gibberd: The Australian industry has got a great track record of picking up new techniques, new technology and adapting to change. I think that's part of the Australian spirit in agriculture. There's certainly a long track record in that space. We're not just creating the innovation, but also picking up on effective innovations that have been developed in other parts of the world. That's driving Australian agricultural profitability. There's no doubt Australia's agriculture is very different today to what it was 10, 15 or 20 years ago. And it continues to evolve with new technologies as they become available.
Jess: Probably fits quite nicely into my next question: overall, what will the future of agriculture look like? Will the industry be able to feed everyone sustainably?
Professor Mark Gibberd: That's a really important question. I wish I had an easy answer to that one, Jess. The reality of the situation is that population is growing and population as it grows has greater demands. We've already talked about the fact that one in nine people don't have adequate food security. They live in hunger today or they live in suboptimal nutrition. So 821 million people today are in that situation. And of course it changes from year to year in different parts of the world, from time to time. Agriculture does a great job of feeding people. When you think of that 2,000 square metres per person, in terms of arable land as it is today, I think we do a really good job at trying to deliver. There's a whole lot that can still be done in terms of better production and better efficiency of production. There's a whole lot that can still be done in terms of not losing the product in the supply chain. And we lose, in many cases, 30 or even 40 per cent of food that's produced, doesn't end up being eaten. Because of losses those in the supply chain, for example, through insects.
David: 40 per cent? That's almost half!
Professor Mark Gibberd: Yeah, that's correct. It can be very, very high. It's food that's thrown away. It's food that doesn't get to be consumed. It's the sort of stuff that dwells in the bottom of your fridge that you throw out at the end of the week when you go shopping again. All of that kind of comes to play and in some parts of the world that's loss in the supply chain before it even gets to people through inadequate insect control or disinfestation, for example. In our part of the world, I suspect there's a lot of people buying food that doesn't actually end up getting eaten or throwing it out at the end of the week when it's gone mouldy.
David: Inspections that the supermarkets do based on appearance and that sort of thing?
Professor Mark Gibberd: Absolutely. There's some industries that produce food that just, you know, a great proportion of it never even gets packed because it's not perfect and that's something that we can address. So when you asked the question: 'What can agriculture do?' I I turn it around a little bit and actually say: 'What's the consumer prepared to accept?' And in different parts of the world, that's very, very different. In our part of the world, we're very focused on quality. And if a product doesn't come up to a quality specification, then it's probably not going to get purchased or it's going to be the last one left on the shelf. In other parts of the world where people are hungry, that's just not such a big issue, right? And people are going to make different decisions about their food preference behaviour and their consumption. But, there's an awful lot that can be done post-farmgate in the supply chain to ensure the efficacy with which food is delivered to people and the efficiency with which people can make sure they consume the food and food's not wasted.
Professor Mark Gibberd: But agriculture is still growing. And in terms of productivity, at least in this country, we're seeing significant gains in yield over time, with record yields being recorded, in non-drought years in particular. Australia has had obviously significant drought for the last couple of seasons in the east and certainly significant drought in the west going back four, five or six years ago. So in non-drought years, we are achieving much better outcomes than we have in the past. And I'm sure that with innovation we'll continue to drive some of that, but there are upper ceilings to that. You can't continue to do that forever. Land itself is becoming less available. So the productive land that we have globally... a significant amount of that comes out of production every year. That's through encroachment from roads or new housing, or industry, or it's through loss of the land through climate change, where it's no longer viable to farm in that particular area, or potentially through land degradation. Compaction or acidification are major issues that often go unseen in agriculture, but in fact they have huge impacts upon potential production of land.
Jess: Gosh, you're right. Not a simple or easy answer, but I do like the way that you turn that back on the listener. It's all about the consumer.
David: It's about you listening at home.
Jess: Exactly. And I'm gonna think about that when I clean out my fridge this weekend when I load in the new groceries. Thank you very much, Mark. That brings us to the end of our discussion. Thanks for coming in and sharing your knowledge on this topic.
Professor Mark Gibberd: It's a great pleasure to be here. Thank you.
David: You've been listening to The Future Of, a podcast powered by Curtin University. If you have any questions about today's topic, get in touch by following the links in our show notes. Bye for now.