Podcast transcript

Podcast transcript

Weed research offers Alzheimer's insight

 Professor Jim Whelan

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Tracy Fortune

I'm Tracy Fortune, an Occupational Therapist and Senior Lecturer at La Trobe University, and you’re listening to a La Trobe University podcast.

Matt Smith

Hello everyone. I'm Matt Smith. Welcome to the La Trobe University podcast. Today we’re going sciencey – we’re talking about plants and my guest today is Jim Whelan.

Jim Whelan

My name is Jim Whelan. I'm in the Department of Botany at La Trobe University. I work on plant energy biology. It’s how plants absorb energy from sunlight and how they use that energy to grow and fight disease.

Matt Smith

He’s been working with a group of researchers at the University of Stockholm, and they’ve been looking at an enzyme in a plant called thale cress. Now it turns out that this enzyme has some pretty interesting functions and it could even to apply to what happens in humans when they develop Alzheimer’s disease. To talk us through the story, he starts by telling us why this sort of research is important.

Jim Whelan

Basically, there’s a need to double food production in the next thirty to forty years. The problem is that all increases in plant productivity in the last twenty to thirty years have required a large input of resources and water, fertilisers, which are very costly, and are limiting. The idea being is we can’t keep doing that to get to doubling in food production that we need. So we need to come up with a new way to make plants more efficient, to actually increase the yields that we want and the way we want to do that is that only ten per cent or less of the energy that is absorbed from sunlight is converted into C6, H12 or 6 which is the glucose, the sugar that we like, and what we want to do is try to increase that efficiency, so that you actually get more glucose or more output or more yield at the end.

Matt Smith

So if only ten per cent of it is being used, where’s the rest of it going? Where’s the 90% going?

Jim Whelan

Okay, the 90% is going on different things. Some of it’s going just for growth, some of it’s going to fight stresses and disease, and some processes in the plants are inefficient from our point of view of trying to get it into yield. Maybe naturally even plants were grown and selected by evolution that were inefficient processes, but like, when you wanted yield, they’re actually inefficient processes. So all plants that we use for agriculture now, you can see the seeds or the fruits are nice, big, juicy, full of either oil or sugar and that’s good. These plants wouldn’t survive in the wild because they’d be instantly devoured by kind of animals and insects and things like that. So there’s other processes to take place in plants which, yes, were good in the two billion years of evolution that plants have gone through, but maybe for agricultural purposes in changing and harsh climates, they now may be wasteful and we have to try and figure out how can we make the system more efficient.

Matt Smith

Tell me exactly how you’re doing the research for this? You’ve got a model plant don’t you?

Jim Whelan

We have a model plant. Thale cress. The reason we use that is it’s small, it grows in six weeks, but it does everything else that normal plants that you see out there do, so it can be used as a model, so it’s easier to work on in a laboratory and it’s obviously much cheaper than having to grow like, hundreds of hectares of wheat or whatever in the outside, to do the work on, so you use it as a model and then what you find out there you try to translate into crops and other plants. So basically that’s what it’s got to do with it.

Its genome is completely sequenced. There’s lots of resources for that model plant available in data banks around the world which you can get for essentially free, and what we do is, we have various questions. So like, one of the questions we have is, sunlight is fixed, it’s converted into sugar or energy in the plant, but then we want to know how that is used in the plant for various purposes. So one of our interests would be, say, during drought, when plants are stressed, and drought is stressful for humans and plants, they stop growing and when they stop growing, they’re obviously not producing yield. So we want to know how you can actually keep them growing on their kind of de-stressors so they still have a reasonable yield and things like that. So really, that’s what it’s about. So, in these model plants, we carry de-stressors out in broad chambers and laboratories and things like that, and then we see how they respond but what we can do is, we can artificially change their genetic make-up or we can alter things or we can pre-treat them with various chemicals and then that might make them more resistant, so it would be just like say what people are more used to the fact that we all get vaccinated maybe when we’re young, or when we’re teenagers, against various potentially deadly diseases, so that when we contract them later on in life, we actually don’t suffer that disease. Well, potentially, you can do the same for plants. You could actually pre-treat it with what might be harmless chemicals that mimic stress. The plants then have a smaller response to that, but then when they get the environmental stress out in the field, they can actually deal with it a lot better.

Matt Smith

So, you’ve been working with thale cress. How much would how that works and how it’s made up, and the different enzymes that it’s got, how much is that transferable to other plants? Is it directly transferable?

Jim Whelan

It’s very transferable. To say it’s directly transferable would be misleading, but it would be very transferable. So cereal plants are a little bit different. They belong to a different group, but they’re still very, very similar in their genomes so a plant is a plant. It kind of has a root system, it has leaves, they produce seeds. So they’re all what we call higher plants. They’re all flowering plants and things like that. So they’re very, very similar. But that’s not to say that some plant species, like you have say, Australian native plants for various things, have developed or required new traits to make them more resistant so some of our colleagues in other places, say, what you get in all things, even in humans, you get duplications of genes or regions of the genome, so you might get more than one gene to do a process, but then one of those genes can specialise, so they find out that when this occurs in certain genes, that it leads to salinity resistance. They’ve been working for this for a number of years, where people in the CSIRO, and they were able to show that when you put this back into wheat and did it, you got salt resistant plants. So even though thale cress is a good model for it, it obviously cannot simulate what every plant does in every situation, but what we can do is, we can take those say, genes for salinity resistance, and we put them into thale cress, and we can say, yes, it gives salt resistance there. You do that in the laboratory. It costs some money to do, but it’s not going to be as expensive as putting it into wheat and putting it out and doing field trials. So, you get a proof for concept first, in that plant, and then when it works in that plant, you try to put it into more kind of like, crop species or agronomically important.

Matt Smith

You were recently involved in some research that came across a new enzyme in the thale cress. Is that right?

Jim Whelan

Yes, well we were involved in some research for colleagues in Stockholm University, which characterised a new enzyme, which is in mitochondria which what I'd say is expend the energy if you want to call it that way. If you want to think of the mitochondria as an engine spending energy, just like all engines, parts of it break down sometimes and need to be removed. Well, they have special other enzymes to remove the broken ones, and this enzyme that we characterise as involved in that process of removing it.

Matt Smith

What’s the enzyme called?

Jim Whelan

This enzyme is called, it’s very scientific, it’s called an organelle oligopeptides, that means it’s present in the organelle, the mitochondria, it’s an oligopeptides, as in it breaks down small proteins. So our earlier work has shown that we characterise a peptide as that broke down bigger proteins into small bits, and this one takes the small bits and breaks them down completely into the amino acids. So hence the kind of scientific name, we just say, oops, or oligopeptides, so oops.

Matt Smith

Can you explain about how these enzymes work and what they do?

Jim Whelan

Basically these enzymes that we’ve been involved in characterising is that when you take a cell, each cell or lots of organisms have 40 or 50,000 genes and that as a strict rule, but genes include proteins and proteins are the machines that do things. And what happens is, these proteins are worked in assembly lines just like you’d have in a factory where one takes the product from another, and does something with it and so on, and so on, and so on. But just like in an assembly line, there are other proteins that are the robots, which kind of take those proteins in and out, because the proteins break down, and they’re recycled. They don’t throw them away. Again, cells are the ultimate recyclers. When the proteins break down, they break them down into their individual amino acid parts, and remake new proteins from them. And some disease, and various diseases like Alzheimer’s, is involved where proteins, plaques form, so that means the proteins that are dysfunctional, aren’t broken down. So what we were doing in our plant-based research, was looking at how, when proteins are in plants and they function in how they’re broken down, then we characterise this new enzyme, and the idea being is that in the same thing in humans, when these proteins break down in the human brain, why aren’t they effectively removed, because clearly it happens most of the time, they are removed, but then in some individuals, over time in the ageing process, they’re not as efficiently removed as they should be. So the idea being is that it allows us to study what are the proteins involved in breaking down those old proteins or removing them. And there’s probably several of them involved. Once you identify new players in the process, it allows you maybe to understand the process in more detail, so it would be beneficial now that for people who’d be working in that area, and I think they’re doing this over in Stockholm University, with colleagues, they’re going to look at the human form of this, to see if there’s any linkage to Alzheimer’s and how it functions there.

Matt Smith

So I can see how you go from thale cress to wheat. They’ve got a lot in common. That’s quite different of course to a human. Do you think that it’s realistic that there’s a lot of overlap between them. I know a cell’s a cell and mitochondria is probably mitochondria from plant to animal.

Jim Whelan

Look, at a molecular level, even though we see there’s a lot of difference between plants and animals, really, as you say, at a cellular level, and more importantly, a molecular level within the cell, the machines, the proteins that do things, once you put them into a test tube, you wouldn’t know the difference between the two of them. Okay? So therefore there’s little or no difference at a molecular mechanism of how these processes take place and in fact if you want to think about it, is that a lot of people would say, oh yes, well, plants are plants. They’ll be different from humans. Well, I put it to you that the whole field of genetics is based on a monk over a hundred years ago looking at peas. Gregor Mendel. People who work in human genetics would say, oh, look what human genetics ... and it does great things. I would never say it doesn’t. If someone hadn’t looked at wrinkled peas and smooth peas, we wouldn’t have the basic laws of genetics. So you can learn a lot by just observing anything in nature and then it can be applied to other things. So there is lots of other examples like that I could give as well.

Matt Smith

My next logical question I suppose is, if you can take research that you’ve done from thale cress and make improvements to wheat crops potentially, can you take research that you’ve done from thale cress and this enzyme in the mitochondria and help people out and make medicines.

Jim Whelan

You can. A lot in between, but one of the most important things about doing research is that it’s not only the specific research you do, it’s the knowledge that that generates, knowledge in itself. So, I wouldn’t say that the enzyme that we’ve used in thale cress or anything like that is going to be used as a medicine for humans, but it’s the knowledge of that enzyme being involved in that process now, allows researchers that work in that specific area to say, okay, we will now test this protein and this gene for its involvement in disease maybe in humans. And so it gives them a target to look at. It gives them another possibility and if it is involved then, because we produced a crystal structure of it, there then maybe we can say, okay, we can maybe modify how this works, or doesn’t work, or we can look at it, so it’s the knowledge that’s generated as much as the actual molecules themselves that are important.

Matt Smith

Okay, so we’ve got a lot to learn from thale cress.

Jim Whelan

Yep. And believe it or not, there’s a lot to learn from those plants that just sit out there and don’t do anything, or that we perceive, as humans, don’t do anything, but they do actually quite a lot.

Matt Smith

That’s Professor Jim Whelan, a botanist from La Trobe University and a specialist in plant energy metabolism. He works at the new AgriBio Centre at La Trobe’s Melbourne campus and he’s also a member of the Australian Research Centre of Excellence in Plant Energy Biology.

That’s it today for the La Trobe University podcast. Don’t forget, there’s lots more podcasts, interviews and lectures at the La Trobe University podcast blog. That’s at podcast.blogs.latrobe.edu.au or search for La Trobe University on iTunes. There’s more than enough there to keep you out of trouble. I'm Matt Smith. You’ve been fantastic and thanks for listening.

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