When in drought – plants and water stress

Interviewer: Sam Walter (Interviewer, Ideas Lab)
Guest: Dr Laura Vickers
Recorded: 24/07/2014
Broadcast: 01/09/2014

Intro VO: Welcome to the Ideas Lab Predictor Podcast from the University of Birmingham. In each edition we hear from an expert in a different field, who gives us insider information on key trends, upcoming events, and what they think the near future holds.

Sam: Today we’re with Dr Laura Vickers who is a lecturer in Plant Biology in the School of Biosciences, here at the University of Birmingham. Hello Laura. 

Laura: Hi. 

Sam: So, can you tell us a little bit about what you do here at the university?

Laura: So I teach currently on the undergraduate course that we have in Biological Sciences and I teach to first, second and third years in mainly the modules that involve environmental science or plant science and ecology, but I also teach a little bit of cell and developmental biology as well because plants also go through development and sometimes we forget that. 

Sam: And we’re here today to talk about the session at the British Science Festival in September, ‘The Secret Life of Plants’. Can you tell us a little bit about what’s going on at the session then and what will be happening in the session?

Laura: So ‘The Secret Life of Plants’ is quite an exciting session that we’re running. It’s going to take the format of an interactive talk – I almost want to put a little boldness on the word ‘interactive’ – we’re going to be running live experiments through the sessions, so it’s not going to be like a very traditional or generic lecture, it’s going to be a talk in which we really kind of want people to come up from the audience and actually set up experiments. So as we’re talking about scientific principles or concepts surrounding plants and how plants talk to each other and how they talk within themselves and to even other species that aren’t even other plants, we’re going to be running live experiments to test those concepts there and then. So the audience can judge for themselves if they think the science is true or not. 

Sam: Fantastic. Sounds like a lot of fun. And so a lot of your research is in what you call ‘water stress’ isn’t it? 

Laura: Yeah.

Sam: And this is how plants respond to lack of water?

Laura: Yeah, so when we sort of use the term ‘water stress’ it can be either way. My expertise is really in the lack of water, so how do plants either tolerate or avoid this. So you can either just not grow in the times when water isn’t available or you can grow in times when water isn’t available but grow in a certain way that allows you to adapt to that. And then there is a flipside to that which is how do plants respond or perceive or cope with when they’re in flooded conditions. So that’s a different type of water stress and I don’t myself work on that; we do have people within the department who work on that sort of side of it. So in those cases we’re looking at them coping with a lack of oxygen and dealing with being underwater. So with my area which is how to deal with a lack of water, I’m particularly interested in how adaptable species are. I will work on a particular species and I will basically take it and stress it under a variety of different treatments and see how it responds and plants, they may appear like they’re doing nothing and they may appear very still on your desk at work or in your back garden but they’ll actually be doing a number of different things. So first off they need to have a way in which they recognise that there’s no water available, so that normally you’d think would be in the roots, which it is, it makes sense to detect that in the roots but you need to be able to detect this and that is usually via enzymes or proteins or sensing chemical changes or sensing mechanical changes as well, mechanical properties of the properties of the plants may change as they lose water. But that doesn’t stop there. So then the plant needs to really communicate that there’s a problem with the rest of the other parts of it, so with the flowers or the leaves or the stem, because this is all happening in the roots. And it can do that in a variety of different ways as well. One of the big things really is hormones. So just like we have hormones that communicate round our body, plants do as well and a lot of people don’t really realise this or appreciate this. So the easiest way is to send this hormone, a chemical messenger and one of the big ones with plants is one that we call ABA and to actually send that through the plant and then you can respond to it. So you might respond to this in the leaf by closing the pores on the underside of your leaf that we call the stomata and you’d want to close the pores so that you’re no longer losing water through your stomata. So if we were to think about it in terms of with people, that would be the equivalent of trying to stop yourself sweating, for instance, although it’s probably not the best analogy to use because that implies respiration and we’re actually talking about transpiration with water, with plants.   

Sam: What kind of ways do plants respond to water stress?

Laura: They can respond in a variety of different ways. They can protect their membranes and their proteins to protect themselves against the upcoming lack of water in their tissues. Or they can try and get more water using a very nifty little trick called osmotic adjustment and it’s quite complicated to explain so I’m going to have to explain it thinking about a box of Lego. 

Sam: OK.

Laura: So you have a box of Lego and you’ve got ten pieces in that box. We all know that you can join Lego pieces together but you’ve got ten small units of Lego, so the concentration we’d say in that box is ten. So it’s a high concentration and via osmosis, if outside the box there was no Lego pieces we’d expect the water to move from outside the box inside of the box because there’s ten pieces within the box. But if we joined up all those ten Lego pieces together so we had one big joined up piece of Lego, our concentration is now one so it’s not as high as it was when those pieces were broken down, when they were individual. So less water will move in. So one of the things that plants can do is if they want to get more water into their tissues from outside, they break the Lego pieces down so you’re going from one big molecule to many small molecules but you’re increasing your concentration because concentration isn’t based on the size per molecule, it’s how many molecules we’ve got. So you have ten smaller ones and then you can rise your concentration internally and bring in water outside, so it’s almost like creative accounting but for plants in terms of trying to get their currency which we can think of as the water. 

Sam: So could these hormones trigger the change in concentration?

Laura: Yes, they can. So these hormones that have been generated in the roots of the plant when they’ve realised that water is getting a bit low, they’re then transported round the plant and they can go to another section of the plant and then they can cause these changes in terms of the osmotic adjustment so that that tissue can get more water. And hormones are really vital for the plant to communicate messages around the different organs of the plant and around the different tissues, just like it is for you or me. 

Sam: So how does this process kind of help us develop drought avoidant crops?

Laura: The way plants respond to water stress is very complicated and each species responds differently. Not all species will do the same thing and so if we can take a plant and we can break down its response and we can work out ways in which it either avoids or tolerates or copes with water stress and if these mechanisms are, say, encompassed in the transcription of a gene for instance, then we can use this information and we can say well, you know, that lettuce there, that’s quite resistant and can tolerate water stress because it has this gene that produces this protein that helps with osmotic adjustment or protects a cell membrane, whatever it is. We can say well that’s our benchmark, we should always breed this variety of lettuce with other varieties to maintain that within the gene pool of the plant. By picking apart the mechanisms and by really, really truly understanding what’s going on, we can maybe get these traits and get these characteristics in new crop varieties and have then crop varieties in our fields that are adaptable, that can either quickly sense change and adapt to it, or that have a really good response once they’ve sensed that water’s getting low in the soil. So it’s multi-faceted really. You’ve got how do they sense it? Can we make how they sense it more efficient? Can we make them sense water stress quicker? And then how do they respond to it? Can we make the response larger? Almost think of an immune response in a person. Can we make, you know, the plant invests lots and lots of resources in coping with that stress so that it survives or do we make that response last longer or occur earlier? And so by understanding the mechanisms we can affect all these different areas.

Sam: It sounds like great news for agriculture and farmers. 

Laura: Hopefully, although it is something that’s species specific so there's a lot of work to do. So we’re already going some way into understanding how some crop species adapt and how we can use various farming practices and we can put that again with the science from the lab and we can tackle those issues, but lettuce won’t respond the same was as onions, and onions won’t respond the same way as oil seed rape, so it is a long process to cover all the crops that we eat and use. 

Sam: A long job ahead. 

Laura: It’s a very long job. It means I stay in a job, which is great!

Sam: Dr Laura Vickers, thank you very much for joining us today.

Laura: Thank you.

Outro VO: This podcast and others in the series are available on the Ideas Lab website: www.ideaslabuk.com. There's also information on the free support Ideas Lab has to offer to TV and radio producers, new media producers and journalists. The interviewer and producer for the Ideas Lab Predictor Podcast was Sam Walter.