Meet the Solutionists, with Mark Scott

Our growing population has a huge number of impacts, but the simplest and most pressing is that we have more mouths to feed than ever before. At the same time, though, climate change is threatening farmland worldwide. That means crops like wheat, which account for 20% of daily calories consumed worldwide, are plateauing. 

Enter: Richard Trethowan and the Plant Breeding Institute. Richard and his team are working on something called hybrid wheat, which will be more robust and productive than the regular plant. They’re trying to make food that’s healthier, easier to grow, and that will feed more people. 

Richard explains why we’ve never been able to make hybrid wheat before, why it’s so crucial to the future of our planet, and how over a century of forward-thinking research has laid the foundation for the work he’s doing today. 

Mark Scott  00:01

This podcast is recorded at the University of Sydney's Camperdown campus on the land of the Gadigal people of the Eora Nation. They have been discovering and sharing knowledge here for 10s of 1000s of years. I pay my respects to elders past and present and extend that respect to all Aboriginal and Torres Strait Islander people.

Richard Trethowan  00:24

We're off to the field site, and we're going to look at all the different strains of wheat and barley. I think we have barley down there, don't we, Peng?

Peng Zhang  00:34

Yeah.

Richard Trethowan  00:35

So all the different strains of wheat and barley that are being tested under inoculation in the field. Now, field resistance, or what we call adult plant resistance, is vitally important, because how it, how it works in the field at the end of the day is what really counts.

Mark Scott  00:55

You're standing between history and the future. Look in one direction, and all you see is nature, a seemingly endless green field. Wheat rustles around you, shimmering in the distance. Turn around, though, and you're in a science fiction movie, the ones where humanity is down to its last survivors, who are desperately trying to figure out how to grow food in an inhospitable environment.

Richard Trethowan  01:21

We're in one of the, one of the temperature-controlled greenhouses. Then we're in the crossing greenhouse, so it's in here that we're doing our what we call our line conversions.

Mark Scott  01:31

You're inside under a plastic roof, surrounded by rows and rows of crops in planter boxes. And the farmers look different too, more like scientists.

Richard Trethowan  01:40

There's some very complex genetics has gone in to creating this individual here.

Mark Scott  01:46

You're at the Plant Breeding Institute at the University of Sydney's Camden campus, and what you're looking at is the future of food. The United Nations predicts there will be 10 billion people on our planet by 2080. Our growing population is a testament to our innovation, but it creates its own challenges too. If anything about a growing population should worry you, it's feeding all those new mouths. So I'm sorry to tell you that over the last decade wheat yields have plateaued. Think wheat yields aren't really your problem? Well, they account for 20% of the calories consumed worldwide on a daily basis. So, what can we do? How do we feed an increasingly hungry planet, if our staple crops aren't growing at the same pace we are? This is The Solutionists, I'm Mark Scott. Richard Trethowan is Professor of Plant Breeding and Director of the Plant Breeding Institute at the University of Sydney, and he's also the man who'll make you excited about wheat. So, tell me, Richard, why do we need to breed new types of crops in the first place? What's the matter with wheat, as we've always grown wheat?

Richard Trethowan  03:11

Well, I think, as you outlined, Mark, I mean, we have a growing population, but it's, that's it's more than just the challenge of more people in the world. We have a changing climate, and the production environments are becoming more hostile, you might say, more difficult. There are higher temperatures, there's more frequent drought, and against that backdrop, we have to increase the productivity in our farmers' fields. Now, there's gonna be no more land for agriculture in the world, really. We're going to have to increase the productivity from the land that is currently available. And that's going to be a massive challenge, and it's not just a challenge for wheat, one of the world's biggest crops, it's a challenge for all the crops that, that we grow and that we eat. 

Mark Scott  03:56

So, I'd have thought that increasing yield, increasing productivity would have been what scientists are naturally delivering for us. Are you saying that, that in a sense, we are going backwards? The productivity increases that we're currently seeing are being overwhelmed by the climate changes and other difficulties that are coming to bear?

Richard Trethowan  04:16

I would say that we have kept pace with those changes because of you know, a whole range of factors, including good genetics. Now, look, food security is very complex, and it's not just the genetics of the, of the plant species that we grow and we eat. The genetics interacts with the management system, how farmers grow those new crops. It interacts with the environment in which those crops are grown, and it depends on the market in which those crops are sold, and the policy environment too. So, it's quite complex, but we at the Plant Breeding Institute are looking more specifically at the genetic component of that complex interaction.

Mark Scott  04:54

So, you said food security there. What do you mean by food security?

Richard Trethowan  04:58

That we produce enough food for everybody, and we produce that across the world. Now, there are parts of the world where we do produce surplus food, and here in Australia, we do that, and we export that food. But there are many environments where there is not enough food produced, and there's a whole range of issues around that, and part of it is poor genetics, poor management practices, a difficult environment, and a poor policy environment as well.

Mark Scott  05:26

So, what are the key elements to food security? If we're getting this right, what's gonna be in place?

Richard Trethowan  05:32

Well, I think it is optimising that interaction, genetics by management practice, by environment, by the market. If we can get that right, then I think we can go a long way to improving food security globally. Now, we're much more focused on the genetic end, and within that genetic scope, we see three things. We think that we can increase the productivity, so the genetic potential of our crops, like wheat, to produce yield, so that potential,

Mark Scott  06:03

And simply that means each crop creates what? More product that we can,

Richard Trethowan  06:09

More, more products, higher yield per unit area. Now that's something that we can do, and we've been playing around with some wonderful technologies. We've developed some wonderful technologies over the last decades that will help us increase that productivity. But that's only one thing. We then need to protect those yield gains. We need to buffer those yield gains, and we do that in two ways. We enhance the disease resistance, we keep ahead of the pathogens, because you can imagine you could have a crop with the potential to produce really high yield, but it becomes susceptible to disease. All those gains are wiped away.

Mark Scott  06:46

Yeah.

Richard Trethowan  06:47

So we need to keep ahead of the changes in the diseases, the pathogens in the environment, and they are changing all the time. They change, they mutate, they overcome the genetic resistances that we often put in place. So we have to keep ahead of that, but it's more than that. With our changing climate, we're looking at higher temperatures, we're looking at more frequent droughts. We can do a lot using genetics to enhance the tolerance of our crops to those major stresses. Once we've done that, I think that we need to, and I think again, genetics does play a role here. We need to make the food products that we're producing more nutritious. So in the case of wheat, we can produce a large volume of wheat, but we need to make that more nutritious. Because for many people, particularly in the developing world, they don't have access to a diversified diet. They might have a lot of wheat in their diet, or a lot of rice. And those crops, while valuable, tend to be a little bit low in micronutrients, for example, so iron and zinc, and some of these these factors, protein, for example. If we can elevate the levels of micronutrients in that food stuff, if we can enhance the nutritional value, then we don't just deal with food shortage, we can also deal with malnutrition. So, yeah, treat that productivity, protect that productivity, and make food stuffs better for you. That's what I think we can do using genetics.

Mark Scott  08:17

That's a great trip tech. Tell us, though, what happens if we can't solve that, if we, if we can't enhance the yield and protect it and have it of greater quality. What are the consequences?

Richard Trethowan  08:29

Oh, well, I think the consequences in the longer term are dire, and particularly for many developing countries with large populations, and I, I look at the subcontinent, for example. Large irrigated systems, falling water tables. There's less snow melt on the Himalayas. There's less recharge of the water table. They’re environments where people are heavily dependent on grain crops, and with declining water, increasing temperatures. Even now, the temperatures in the subcontinent are much higher than average, and that's also suppressing yields. What are people going to eat? This, this is going to be a major problem. And can countries like Australia produce enough surplus, for example, to export that surplus? But you know, I'm, I’m, I'm optimistic. I actually think that by optimising that interaction that I talked about earlier, if we can do that and work, it's a whole lot of scientists working together, you know, crop geneticists, agronomists, serial chemists, for example, economists, all working together to optimise that interaction. We can ensure, we can mitigate the effects of our changing climate.

Mark Scott  09:49

So there's a lot of discussion about hybrid wheat and what hybrid wheat might be able to do for us. Tell us about that.

Richard Trethowan  09:55

Okay, let's, first I want to talk about maize, or corn. Corn is the, what we call the great hybrid crop. It's an open pollinated species, and you can very easily cross one corn plant with another to produce progeny. We call these first cross progeny that exhibit hybrid vigour. Now, the problem with wheat is that it's self-pollinated, so you can't easily make that cross between two lines to produce a first cross progeny, and that the farmers could then grow to benefit, to get the benefit of hybrid vigour,

Mark Scott  10:32

And hybrid vigour is when you, you cross over and get a stronger, a greater strength as a consequence of that? A robustness?

Richard Trethowan  10:40

It is a robustness, but it is the first cross seed, so between two parents, so two, two unrelated parents within a crop species. You cross them together, that first cross progeny can produce, not always, but it can produce much, much higher yield. We call that hybrid vigour.

Mark Scott  10:56

So, you can do that with corn and maize, but you can't do that with wheat.

Richard Trethowan  11:00

You can't do that with wheat, because it is self-pollinated, so,

Mark Scott  11:02

You're getting no crossover.

Richard Trethowan  11:04

You can't get the crossover; you have to actually make the cross by hand. So, how do you make the thousands of tonnes of first cross seed that you would need to make to give to farmers to sustain a hybrid wheat industry? You can't do it. Until now.

Mark Scott  11:18

So, so what are you doing?

Richard Trethowan  11:20

Until now. Yes, that's right. So, basically, the culmination of 30 years of research has allowed us to circumnavigate this constraint of self-fertilisation in wheat. So, we've developed a system that produces what we call male sterile wheat, so it is female fertile but male sterile. And that's really important because we can plant that male sterile wheat out in the field, and alongside it, plant a male fertile wheat, and the wind will do the work for you. It will move the pollen onto those fertile stigmas on the male sterile wheat, and every seed we harvest off that male sterile female will be hybrid. And that allows us to produce the hundreds and thousands of tonnes of hybrid seed that we will need to sustain a hybrid wheat industry. Now, the issue with this is, you have to buy the seed every year. With corn or maize, that, that, that's how it works. You buy your hybrid seed, you get the benefit of hybrid vigour, and the next year you've got to go back and buy the seed again. As a result of that, there is more money spent breeding corn in the world than all other cereal grains. It's because there's a significant commercial value,

Mark Scott 12:38

There’s a market for it, 

Richard Trethowan 12:39

There’s a,

Mark Scott 12:39

‘Cause everyone’s buying it.

Richard Trethowan 12:40

Absolute market in it. Then you need to go back and buy the seed, and that generates income, and that generates research, and that's the story of maize. With self-pollinated crops, you can't do that, until now. So we've developed a system that allows us to not only produce that male sterility but maintain it as well, so to keep producing it over time.

Mark Scott  13:00

And what are you seeing? What are the attributes of hybrid wheat that you're seeing using this system?

Richard Trethowan  13:04

Oh, we're seeing higher yields, definitely. And you know, one of the big advantages, it's not just the higher yield and the greater productivity, which is, you know, we'd need that. It's also more stable yield over time. So, what we see, the hybrid wheats are less affected by the vagaries of the environment. So across years and environments we see less change in the yield, and that's going to be really important with climate change, with our changing environment. Already here in Australia, we're seeing, if you look over time, we're seeing much more variation in temperatures and in rainfall patterns. That's always been our environment, but it seems certainly over the last two decades to becoming even more variable. So, being able to deploy seeds of a species like wheat that produce a more, not only a high yield, but a more stable yield, it's going to be really important. And not just here in Australia, we see this as having a significant impact around the world as well. So we have entered into a partnership with the fourth largest seed company in the world, KWS, and we will be deploying this technology in the developed world, and we hope to derive a royalty benefit from that, of course. But in the developing world, we will be making this available under a humanitarian licence, so it will be free in the developing world, and we see that as having a significant contribution to food security, particularly in those geographies where wheat is really important and forms a very large part of the diet. You know, there are, there are countries where people, on average, this is per capita, consume 250 kilograms of wheat a year. Now you imagine those sorts of consumptions, if we can increase that productivity, if we can stabilise the yield in those environments, if we could make that wheat more nutritious, what an impact we could have. Now we're just walking past one of our seed stores, may as well have a quick look. We have probably at least a couple of hundred thousand different accessions or genetic strains all in these little envelopes here, and we have a database that links all of these together. This is a cold place, you'll feel the coolness here, low humidity, and we can store seed here comfortably for at least 10 to 15 years. Let's come in here, and I'll show you some of those haploids growing on. It's in that, it’s in the test tube, so it's only what would that be? Five centimetres long, maybe less, and it has agar in the bottom. And on that agar an embryo was placed. Now that embryo has started to grow, as you can see, there's green leaf tissue. There are roots going down into that media. That plant is haploid, that has half the number of chromosomes. We grow that on, it'll be completely sterile. Now, what we do is take that plant out of the media, wash the roots with colchicine, that causes the chromosomes to double, and we then have a fully balanced fertilisation. So we have a plant that is fully fertile and completely true breeding. We're just walking through our controlled environment chamber area at the moment, so we have these chambers with temperature and light control, much better temperature and light control than the microclimates. Now, here you'll notice those big tanks, they're full of liquid nitrogen. And inside those tanks is the history of rust pathogen changes in Australia. It's an incredible resource for research, you can imagine.

Mark Scott  17:07

You've been working on this for 30 years. Why has it taken so long to crack this?

Richard Trethowan  17:11

Well, it began long ago. In fact, I did my PhD here at the University of Sydney. My supervisor at the time had the idea.

Mark Scott  17:20

Right.

Richard Trethowan  17:20

And was a great idea, but technology was not really, and he did work on that for a number of years, and he made some progress. And it's only been probably in the last 10 years that that progress, that rate of advance, has been exponential, and that reflects the changes in genetic technology available to us now. So advances in molecular cytogenetics, for example, have been absolutely fantastic, and we've been able to, what we call play the numbers game. It's all about probabilities, finding those unique individuals, and we've been able to play that numbers game, find that unique individual, and we cracked it. We found it.

Mark Scott  18:05

Was it a eureka moment, or a sense of, were you always confident that if you tried enough variance, if you worked it hard enough over time, you would get there?

Richard Trethowan  18:17

Oh, we always thought we would get there. We thought it was, it was a matter of, would we get there next week, or would we get there in five years. It was that type of equation that we were dealing with. It was a great idea, but with the technologies available to us now, we were able to move the odds into our favour, and we were able to find that, that individual.

Mark Scott  18:39

When you say that individual, you mean?

Richard Trethowan  18:40

A single unique rearrangement in the genome. Now, the system that we have developed is non-transgenic, I think that's really important.

Mark Scott  18:49

Which means what?

Richard Trethowan  18:50

That means is not a GMO.

Mark Scott 18:52

Right. 

Richard Trethowan 18:53

So, we haven't used genetic transformation to move genes across species. We use traditional cytogenetics to do that. You don't need any harsh chemicals to use it, which is also a tremendous advantage.

Mark Scott  19:07

So, just explain that to me a, a, a bit more. So, this isn't a genetically modified crop?

Richard Trethowan  19:13

No, it's not. It's not a GM, what you call a GMO. So it, it is, it doesn't fall under that legislation or that restriction that you see in many countries, including our own. Can be deployed immediately in the environment.

Mark Scott  19:28

Right.

Richard Trethowan  19:29

Because it's constructed from natural variation within the wheat gene pool.

Mark Scott  19:32

Right.

Richard Trethowan  19:32

So look, the wheat gene pool is quite broad. I mean, let me explain wheat. Wheat is a fusion of three species, anyway, and they're crosses that occurred in nature thousands and thousands of years ago. And there are lots and lots of wild relatives of each of those three species that were involved in that original fusion, if you like. We've gone into that broader gene pool, we've found that diversity there, and we've brought it into modern wheat.

Mark Scott  20:00

So you've searched for it amongst the diversity that's there,

Richard Trethowan  20:03

That's correct.

Mark Scott  20:04

You found it, and then utilised these fertilisation techniques. 

Richard Trethowan  20:08

Yes.

Mark Scott  20:09

And then you've identified what really works effectively and well for you in terms of yield uptake.

Richard Trethowan  20:15

That's what we've done. Well, the first thing was we needed a way of making hybrid wheat. We always knew, we always thought there'd be hybrid vigour there, but without an effective system for exploiting it, it was always theoretical. Now, what we have come to understand, and this is getting a little more complex, is that with wheat you don't automatically find hybrid vigour, you have to breed for hybrid vigour. And that is because of wheat self-pollinated nature, and what plant breeders have been doing, or wheat breeders have been doing for the past century. What they, what they do is they take their best line and cross it with their best line. In order to see hybrid vigour, you need to have what we call heterotic, or different gene pools, 

Mark Scott  21:03

They’ve got to be different. 

Richard Trethowan  21:04

Quite different and distinct.

Mark Scott  21:04

It’s got to be distinct, right?

Richard Trethowan  21:05

They have to be different, but if you keep pushing everything together, 

Mark Scott  21:06

Yeah.

Richard Trethowan  21:07

Those different pools cease to exist. 

Mark Scott  21:09

Yeah.

Richard Trethowan  21:09

So what we're doing now is, in a sense, reconstructing those pools, those separate pools of parents that you need to have. You need to have a male pool and a female pool that are very different, that when you cross them, will produce those individuals that have this special advantage when it comes to yield.

Mark Scott  21:29

If you look now at the opportunities of rolling out hybrid wheat worldwide, what are the barriers? What are the challenges that keep you awake at night to scaling this effectively globally?

Richard Trethowan  21:42

Well, that's a good question. Because with a technology like this, and it is a new technology, it is hard to predict just how things are going to work in different environments. So I guess the thing that I'm most worried about, and particularly here in Australia, is when the first hybrid is released into the marketplace, will it perform? Because a great technology could get a bad name if the initial cab off the rank, so to speak, doesn't do what we say it should do. So, and that might be that we have a drought year, so you release a fantastic hybrid. It's a drought year, you can't see the expression of the value of the hybrid because of the limited moisture. That could be a problem. Could be a problem, because uptake of these sorts of technologies is about perception too. And I think,

Mark Scott  22:38

People having confidence, 

Richard Trethowan  22:39

Having confidence. So you know, I think initially that's going to be really important. In the developing world, we are working already in Pakistan, in Bangladesh, in Ethiopia. We're extending that work in new projects to Egypt and other places, and there my primary concern will be the fact that small scale farmers will need to buy seed each year, so the policy environment locally will be very important as well. Hybrids, hybrid seed will need to enter the local seed certification system. You know, taking a great technology, showing that it works in that environment is one thing, getting it to farmers at a decent price is another thing.

Mark Scott  23:25

Richard. You're clearly a big thinker who takes on big challenges. Think ahead, you know, past your career, you know, with the generations to come. What are the other great challenges in, in food security that you think we're going to have to take on, and how will that change the way we're farming and eating in a century from now?

Richard Trethowan  23:48

Oh, well, it look so much depends on climate change and what happens to our environments, and I guess let me explain. One of the things that we are doing here in Australia, we're leading a national initiative to try and improve high temperature tolerance in our crops. And in doing that, we're using an unusual environment that's Kununurra in the far, far north of Western Australia as one of our test environments. Now, that's, that's in the tropics, that's a very, very hot environment. And we're planting wheat up there. Our new genetics, so we assemble the genetics using advanced genomics and phenomics, and we identify materials that we believe have you know, elevated levels of heat tolerance. We take it up there and we test it in a super hot environment. And if it works there,

Mark Scott  24:39

Yeah.

Richard Trethowan  24:40

And it, and they do. We identify materials that do, they perform very well in those tough environments. Then we're very confident that we've got something. Now, that environment might represent the northern edge of the current wheat belt in the future, should the most dire,

Mark Scott  24:55

Right. To where we might,

Richard Trethowan  24:56

Effects of climate change come to pass, right?

Mark Scott  24:58

To where we might be growing the wheat.

Richard Trethowan  24:59

It's where, it might well be that, that, that the environments in which we're growing wheat in the future are like that, so we're going to be prepared for that. Now the question, the challenge is, how far can we push a crop like wheat, and I think the big challenges going out for the future will be changing photosynthesis. So the ability of crops like wheat and rice and sorghum to produce carbon, if you like, in an increasingly warm environment, and that's going to be a big challenge.

Mark Scott  25:39

That's Professor Richard Trethowan, Director of the Plant Breeding Institute at the University of Sydney. And if you want to hear more about food and human health, you'll enjoy our episode with Professors Steve Simpson and David Raubenheimer.

David Raubenheimer  25:55

The problem is that foods are engineered, processed foods are engineered by food engineers in corporations, specifically to, as Steve said, to override those regulatory mechanisms that tell us when we've eaten enough, because eating enough is not a good business proposition for a processed food manufacturer. Eating more is a better proposition.

Mark Scott  26:18

You can listen to that episode of The Solutionists right now, and make sure you're following the show, so you don't miss an episode. The Solutionists is a podcast from the University of Sydney, produced by Deadset Studios.

The Solutionists is a podcast from the University of Sydney, produced by Deadset Studios. Keep up to date with The Solutionists by following @sydney_uni on Facebook and Instagram, and @sydney.edu.au on Bluesky.

This episode was produced by Liam Riordan with sound design by Jeremy Wilmot. Supervising producer is Sarah Dabro. Executive editors are Kellie Riordan, Sladjana Rstic, and Mark Scott. Strategist is Ann Chesterman.

This podcast was recorded on the land of the Gadigal people of the Eora nation. For thousands of years, across innumerable generations, knowledge has been taught, shared and exchanged here. We pay respect to elders past and present and extend that respect to all Aboriginal and Torres Strait Islander people.