Program: Breeding wheat to resist the heat

Robyn Williams: And our final high-achieving woman is one of our past Top Five Scientists, feeding the world, Dr Rebecca Thistlethwaite, showing how wheat crops can be helped to resist the increasing heat.

How did you find the exercise of being a Top Five Scientist with us?

Rebecca Thistlethwaite: It was wonderful. Not only did I get to meet so many different people and gain the experience that I would never have been able to get elsewhere, but being able to make the contacts that have stayed with me from that time. So yeah, I've been able to make a lot more contacts, have a lot more experiences than I originally thought I would.

Robyn Williams: That's good to know. But how many people do you think, as you travel around, know about where you live, Narrabri, further north in New South Wales? It may not necessarily be known so well by most Australians.

Rebecca Thistlethwaite: No, you're quite right. And I didn't know where it was when I first moved there myself. So my husband likes to say that it was named the sportiest town in Australia in 2001 or something like that, and the whole of the town keeps that as something that is so important to them.

Robyn Williams: How come?

Rebecca Thistlethwaite: Well, we do have actually recently two Olympians that went to Paris from Narrabri. So that's pretty fantastic given the size of our town, we're a 7,000-person town.

Robyn Williams: Very interesting. Now, I always associate you with great big, long pastures and standing amongst the crops wearing a straw hat and the sun beating down. Is that more or less your life?

Rebecca Thistlethwaite: It is more or less my life. Actually, it's interesting to tell people that my work day is not in a lab. I'm a scientist, but I'm not in a lab. I am in the field every day, and one of the best things about my job is the fact that I get to be in beautiful fields of wheat. Sometimes it's extremely hot, yes, but it's a very different way for a scientist.

Robyn Williams: How hot does it get?

Rebecca Thistlethwaite: So during harvest, even this year, we've had up to 38 degrees or so through the harvest, and during summer, during the really peak time of summer in January or so we'll get into the 40s generally. So it does get really, really hot.

Robyn Williams: And are our crops such as wheat able to adapt to such things?

Rebecca Thistlethwaite: Over the years we have been able to make considerable genetic gain, and then just in the last certain amount of years we've had a smaller amount of genetic gain, and so we're not finding that we have the diversity that we used to have. There is diversity for things like heat tolerance, drought tolerance, and maybe that combination effect of heat and drought, and then increasing carbon dioxide, and we are making some gains there. So the work that we actually do at the University of Sydney is looking at developing crops for their tolerance to heat and drought in particular. And it's actually interesting that the international germplasm that we bring into Australia gives us that diversity that we need to be able to keep Australian grain growers very, very happy.

Robyn Williams: But what sort of measure is it of survival, that you get more weight of crops or what?

Rebecca Thistlethwaite: Yep, so it's all to do with yield. Yield is king, and so when you talk to industry, and all of the research that we do at the Plant Breeding Institute in Narrabri has to be industry relevant. So our grain growers are our key customer, and our plant breeding companies are as well. And so yield is key. And so whatever we do within the university has to mimic what we would do within a breeding company's context to be relevant to what they need to be able to produce the perfect amount of wheat for the Australian market.

Robyn Williams: What's the mechanism though? Because they don't have sweat glands or anything, or maybe their versions of it, those little holes in the leaves which can transmit water. Is it by transmission of water more vigorously, or what?

Rebecca Thistlethwaite: This is still actually under debate, and it can depend on the variety as well. So, like you say, stomata, the little pores on the leaf, they actually do contribute considerably. But there are other mechanisms. So we're starting to find that…we test thousands and thousands of different genetic lines of, say, heat tolerant wheat each year, and the diversity amongst them can be seen in things like a waxiness on the leaf, and there is a perfect amount of glaucosity that actually makes that particular plant more heat tolerant or less. And so if you have too much, the plant can't sweat, essentially, and so it actually deteriorates that plant. And it's an interesting measure because you can't actually test it in all environments. So we're testing wheat lines in a place called Kununurra in Western Australia, an extremely hot environment, a very tropical environment, very different for wheat. We're seeing that that glaucosity is able to be shown much more prominently in that environment, but we don't necessarily see that particular mechanism shown in Narrabri at all stages. So we go to Kununurra, we see which ones are more glaucus in that environment, and then we're able to select them in Narrabri and they're generally more high-yielding.

Robyn Williams: I'm going to ask you a lateral question, I'm afraid. When you've got all that stuff, the stalks and the rest of it, which are possibly more robust, as you say, covered in glaucosness, what happens to the residue? Is it just thrown away or buried, or what?

Rebecca Thistlethwaite: So when we harvest, generally we try to do a minimal tillage across the environment, to try to make sure that we keep as much moisture and groundcover there for the next season. And so it does, to some degree, mulch into the ground. And when we harvest, we take just the head of the wheat plant generally. But that straw actually causes a lot of trouble at times, because if it falls over (we call it lodging), a grain grower is going to be very, very unhappy with that particular type of wheat. So, yes, straw is very important in both the pre-harvest and the post-harvest.

Robyn Williams: Let me tell you why I asked, because a couple of weeks ago I broadcast something, actually it was a brilliant PhD student from Nigeria, and she was working on sugarcane to make bricks with a tenth of the CO₂ emissions, because concrete itself is pretty bad, and this is Sugarcrete. And now they are building their first constructions in India from this work in London by this Nigerian PhD. And if you can imagine all that residue, not just sugarcane, possibly wheat would suit as well.

Rebecca Thistlethwaite: Absolutely. And that's what we see in certain countries overseas. So in Australia we don't have the necessity for the straw to be long, for instance. So a plant breeder in Australia may not find that as a good trait to have within their wheat crop, whereas if we go overseas, they definitely need the length of straw to be able to use it in other ways. So I see that, I see the importance of that, absolutely.

Robyn Williams: Because the Green Revolution was based on having more in the food end than down below.

Rebecca Thistlethwaite: But I think that we don't actually appreciate the fact that there are a lot of other purposes for whatever is left over, and so that's interesting in an international context.

Robyn Williams: One thing about Narrabri, going back to where you work, is of course there's a famous (or it should be) space station there, the compact array of…I think it's 22 great big dishes. You've been there?

Rebecca Thistlethwaite: I have been there, but I have to admit that it is not particularly on my radar. It should be now that we've talked about it, definitely. But when I do talk about Narrabri, a lot of people do say, oh, that's where the big dishes are, isn't it? Isn't that this certain place in Australia? So it's very famous, very famous.

Robyn Williams: Famous indeed, I think it's called the Paul Wild Observatory, radio astronomy, and it's out there…for instance, in Coonabarabran, not terribly far away, northern New South Wales, the famous Anglo-Australian Telescope, which celebrates its 50th anniversary. But back to your own work, what sort of impact are you having sharing ideas with people from overseas?

Rebecca Thistlethwaite: So, recently we've been working with the Australian Centre for International Agricultural Research, looking at bringing a hybrid wheat system into places like Pakistan, Bangladesh and Ethiopia, and that has been an amazing feat of technology from the University of Sydney. Hybrid wheat has been worked on for about 160 years now, but has never actually been a perfect system for hybridity. The university has patented a new technology, and the idea is to take it into these countries, have it locally led by the country, and then be able to make sure that they're completely sustainable by the end of the project.

Robyn Williams: And when you bring your new ideas there, are they taken up very easily or quickly?

Rebecca Thistlethwaite: Yes, absolutely. And we're really lucky with the partnerships that we have within those countries. So we have developed (over many years, not just in the last few) contacts, and knowing how the government works, knowing the right people to be able to contact and keep the momentum in the science. We keep our scientists happy, and they move through this technology really easily.

Robyn Williams: Isn't that exciting! And what most recently have you done in that international quest?

Rebecca Thistlethwaite: Earlier in the year we went over to Pakistan and visited multiple farmers that are actually taking this technology into a commercial context. It hasn't been done in other countries yet with this particular hybrid wheat system, but it is fascinating to see the social implications of it actually being taken up. So we're seeing a 20% increase in yield. And the thing is that the way that the system works allows these farmers to be able to move with whatever the climate is goi ng to throw at them, whatever is going to come to their environments in the future, they will be able to be sustainable for the very long term.

Robyn Williams: One thing, finally, that you said before, which I find amazing, you said you've got all these…I think you said hundreds of different genetic strains of wheat. I had no idea there were so many varieties kicking around.

Rebecca Thistlethwaite: Oh, tens of thousands, you would say, and the same with most other food crops. And being able to bring in that international germplasm, like I mentioned earlier, is really crucial to our Australian context, but also being able to have that germplasm exchanged internationally as well from Australia, because what we've found is that germplasm that works really well in Narrabri also works in places like Sudan, so we're able to exchange that and also build those partnerships and relationships at the same time.

Robyn Williams: I wonder how many Australians actually know what work is done here for international interests in just keeping people fed.

Rebecca Thistlethwaite: And amazing that the foundations can be built in Australia. I think we hold back as Australians in terms of the technology that we have within agriculture, and it's amazing to see what it's actually doing overseas.

Robyn Williams: Well done. Good to see a Top Five Scientist again.

Rebecca Thistlethwaite: Thanks, Robyn, I appreciate it.

Robyn Williams: Former ABC Top Scientist, Dr Rebecca Thistlethwaite in Narrabri.