Instant Genius - How plants can survive space missions and Chernobyl

Episode Date: February 1, 2018

The world seems to be going ever more nuclear, but what effect could radiation – from bombs or nuclear meltdowns – have on animals and plants? Hosted on Acast. See acast.com/privacy for more information. Learn more about your ad choices. Visit podcastchoices.com/adchoices

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The lack of gravity in space confuses the plants more than any radiation dose they're getting, really. Hello and welcome to the Science Focus podcast. I'm Daniel Bennett, the editor of BBC Focus magazine. At the moment, the world seems to be going ever more nuclear. Governments are keen for us to increase the use of nuclear power to cut greenhouse gas emissions, while the US and North Korea at loggerheads over nuclear warheads. Plus, if we want to set up a base on the moon or Mars, we're going to have to figure out how to grow food in an environment

that's been bombarded by radioactive cosmic rays. In this episode, Focus's production editor, Alice Lipscomb Southwell, meets Professor Neil Willey from the University of the West of England. His work takes a look at the effects of radiation on plants. Not only is he studying tomato and rocket plants grown from seeds exposed to cosmic rays aboard the ISS, but he's also ventured to Chernobyl to monitor the effects of a nuclear meltdown on the surrounding area.

You're listening to the Science Focus podcast from the BBC Focus magazine team. With the UK's best-selling science and technology monthly, available in print and in several digital formats throughout the world. Find out more at sciencefocus.com or look out for us in your app store. I understand that you've got some rocket and tomato seeds and they got sent up to the ISS. Yes, yep.

So when did that happen? And when were they sent up to the ISS? Well, we've got two kind of different lots of seeds. One were some rocket seeds that went up with Tim Peake. They were part of a project that was managed by the European Space Agency and by the Royal Horticultural Society in England. And they went up, I think, in December 2015, they came back down in June 2016 at the same time as Tim Peak.

And that, well, sorry, I should say we've got tomatoes. seeds as well, which were there from a big Canadian project called Tomato Sphere. And the tomato seeds that we got went up to the International Space Station in 2017 and kind of came back in July, August, 2017. Okay, then. So they worked for a few months then, both the sort of tomato and the rocket seeds? Yeah, they're both up there for six months. And that's kind of how long it would take on a manned space flight to Mars, probably.

Okay, so have they come back to Earth, are they all being planted up now? Yes, both of them actually are part of quite big schools projects. We were just sort of piggybacking on the back of these schools projects. So the Canadian one, particularly the tomato seeds, just absolutely lots and lots and lots of seeds have been sent to schools all around Canada for school children to test their germination and to see how they grow. But also the rocket seeds were sent to lots of. and lots and lots, I think more than a thousand schools in the UK for school kids to germinate and see how they grew. So why did you choose rocket and tomato seeds in particular? Are these,

is there any reason why or just because they're a sort of food crop or? We didn't really choose them. We just kind of got some seeds from ongoing projects that these other people were kind of carrying out. But I mean, the rocket seeds were obviously because they were going up on a rocket. And I guess that, that, that, to the school kids. And it made for some quite good kind of logos for the projects and things, these kind of rocket seeds going up. But the tomato seeds, basically, it's a food crop.

And quite a lot of the interest in plants and seeds in space is for providing food on space flights for astronauts. So tomatoes are just a widely used food crop. And we know lots about their physiology and genetics and their growth. So I guess it's quite an obvious thing to pick. It's an easily grown crop plant. Now, all right in thinking that this is really important research because, obviously, if we did do a trip to Mars or a trip to the moon or something,

then the plants would get exposed to quite a lot of radiation from cosmic rays. And so you want to sort of see how that's going to affect the plants? Yes, yeah. I mean, the most important thing is, as yet, nobody's invented away for anything else to happen, other than we're going to have to take all our food. with us to Mars, and mostly that's going to have to be in the form of crop plants to grow as we go and if we colonise Mars, because we just couldn't take enough food with us for the long journey or for anybody to spend any time on Mars, just the kind of amount of food would be too much to take.

So there's, you know, a lot of interest in plants in space just because we have to take them on a spaceflight, but also because on spaceflight they get exposed to a lot of radiation. And this is partly because if you imagine a kind of a spacecraft going through at deep space, it gets exposed to radiation from absolutely all directions. Actually, when you land on Mars and you colonize Mars, Mars itself kind of shields you a bit from some of the radiation from kind of one half of the universe if you're sitting on the surface of Mars, but you get it from the other half. So actually one of the issues is the radiation in a little kind of spacecraft going through space on the way there

there's also that the radiation on the surface of Mars, for example, is much higher than it is on Earth because there's no magnetosphere that surrounds Mars and there's nothing to kind of decrease some of the cosmic radiation reaching the surface of Mars like there is on Earth. But part of the issue is getting there because the spacecraft is particularly susceptible to radiation from absolutely all directions from across the universe. So from your research, if you sort of found that radiation, radiation does affect the plants in any way, like negative or positive, or are you still waiting to find that out? We're still waiting to find some of it out, but we've grown a number of the rocket and tomato plants from the seeds that have been up on the International Space Station.

And it has remarkably little effect on the plants. You can find a few subtle effects, but it doesn't really have much effect on the plants. It has certainly much less effect on the plants than it does on the astronauts. And, you know, there are well-known. effects of space radiation on astronauts, and so in spacecraft, they're shielded from some of the radiation and so on, but even then, the radiation has some effects on them. The radiation certainly has much fewer effects, if any, on the plants than the lack of gravity. Plants are very, very sensitive to gravity. So obviously, when a seed germinate, part of it knows to form a root and grow down, and the other part of it knows to form a shoot and grow up. And that's all because it's sensing gravitational fields. So actually the kind of the lack of gravity in space confuses the plants

more than any radiation dose they're getting really. So when you put them on the space stage and bring them back down here and germinate the seeds, the plants grow pretty well, really. So do we think they've got any sort of natural defences against radiation? Seeds are certainly pretty resistant to the effects of radiation. It's not really because they've kind of naturally evolved defence is to radiation itself, but just because a seed is a plant's way of surviving all sorts of environmental insults and stresses that are thrown at it, and because seeds are kind of, they're really, really dehydrated. So most organisms like us are about 80% water, a seed is only about 10% water. And so it's like a dehydrated living thing that's in sort of suspended animation.

It's not dead. I mean, if the seeds completely killed, it won't germinate again. But it's sort of in suspended animation. And in that state, it's pretty resistant to all sorts of stresses, including radiation. So, you know, a reasonable amount of radiation on a seed often doesn't affect them that much. And some people think that if you give seeds a small dose of radiation, it actually helps them germinate better. Okay. So if we grew these seeds that have been up on the ISS,

would they be safe for us to eat or because they've been exposed to radiation at some point, would they be bad for us to eat or, you know, does it not really matter? I don't think it has any effect, really. The radiation in space is just not big enough to make any differences that matter as far as the kind of quality, the food that you could grow are concerned. Technically, if radiation levels get, you know, somewhat higher than the amounts you get in space, it could kind of mutate, cause mutations in DNA, and it might cause mutations in a gene that did something a bit funny

that might make it not very good to eat. But those are just much higher levels of radiation than the ones that you get in space. Okay, so if we did set one of these bases on the moon or Mars or something then, as long as we could provide some sort of gravity, so the plant near which way was up and which way was down almost, then the plants could sort of be grown quite happily, really, by the looks of it. If we could get the right soil for them,

Yes, yes, you could, yeah, and there is, there is of course some, some gravity. I'm afraid I can't quite remember how gravity on Mars compares to gravity on Earth, but there's some kind of effects of gravity there. So actually, that's not so much for a problem when the kind of, if you grew them on Mars, but some kind of shielding is probably desirable for the plants because the doses on Mars are quite high, in a bit higher than they'd get on the International Space Station. And if you go off into kind of deep space, the radiation gets higher than up on the International Space Station.

So some kind of shielding for the plants might be beneficial, but it might not make that much difference. But you probably need shielding for anybody who is going to look after or tend the plants because the effects of radiation on humans on the surface of Mars are quite significant over long periods of time. So some kind of shielding is probably necessary. But then, yes, with the right kind of soil or basically it'll more or less certainly be in hydroponic systems, I should. think, you know, kind of nutrient solution-based growth. There's, you know, plants, if you provide them with the right amounts of light and carbon dioxide and things could quite happily grow on Mars. Well, they're better defended than we are, then really, aren't they, by the sounds of it? Yeah, they're kind of basically probably not as sensitive to some of these primordial

stresses. I mean, radiation, there's natural radiation on Earth. And in the deep past, there was more radiation on earth than there is now. So some of these kind of primordial stresses, things like plants are a bit less susceptible to than complicated animals with central nervous systems and things. Because I'm right in thinking as well, but like with Chernobyl and places like that where there have been, where there has been a lot of radiation, that plants have sort of been quite happy with it as well, haven't they, they've reestablished it and, you know, everything's kind of all right, isn't it? From plant's point of view anyway. Yes, the thing, The thing about Chernobyl, and I'm part of a big research project that's just spent the last five years doing a lot of research at Chernobyl on the plants and animals there.

But the main thing to remember about Chernobyl is that the different amounts of radiation that we can be talking about, there were forests very close to the reactor when it exploded that just got unbelievably high doses of radiation. and those kind of trees and plants weren't okay. And even now there's quite a strong gradient of radioactivity. So there are places where there's high patches and places where there are low patches. But actually even where the forests were destroyed by the effects of radiation and by the effects of the blast,

in those places, you know, a forest has redeveloped. It's not redeveloped in some of the areas that got the very highest doses, but we're talking about really, really significant doses like nuclear blast type doses in those places. A forest has recovered. It's not quite the same as it was before, but it has recovered.

But in other places along the dose gradient, there can be areas of quite high radiation where the forest, to all intents and purposes, many of the plants, lots of the animals, are quite happy living in those places that have got quite high levels of radiation, you know, compared to any that you would usually find in the environment. So yes, the plants and even the animals at Chernobyl,

turned out to be actually a bit less susceptible to the effects of radiation than some people might have thought. Yeah, I mean, I suppose it's one of those things as well, if you sort of test it over the generations as well and sort of see future generations, you know, how the sort of, if genes have got affected at all. Yes, and it's interesting. One of the things that we've been doing on the project that I'm part of that's funded by the Natural Environment Research Council is to try and look at the effect of Chernobyl levels of radiation over many generations, because there's been lots and lots and lots of studies at Chernobyl, but people tend to go in and get some samples and then come out again,

and they haven't really kind of studied any effects that might be occurring over multiple generations. So we've been trying to do that back in the lab here, actually, to follow things for multiple generations. But, you know, there's been surprisingly few multi-generational experiments at Chernobyl. There's been loads and loads of experiments there. And Ukrainian and Russian scientists did an enormous, amount of work in the kind of 10 or 15 years following the disaster. But yeah, some of the multi-generational stuff is quite interesting to follow.

But on the project that I'm part of, we don't think that you find anything like the level of effects that have sometimes been reported from the Chernobyl exclusion zone by non-scientists, but also by some scientists as well. Yeah, I mean, it's supposed it's quite a sort of current topic, isn't it? Because obviously with greenhouse gases, people are looking to nuclear, saying it's sort of a clean energy. resource, but I know there are lots of concerns among the public thinking, well, if there was a nuclear meltdown, then you know what would happen? And so that is a concern. Certainly. Certainly it is. And I mean, basically in the UK, we've decided to build at least

one new nuclear power station in order to try and meet our carbon emission targets. There is a little bit of a debate to be had about the carbon emissions that are involved in actually building a nuclear power station and then taking it apart at the end of its life. And if you add those to the carbon budget, the carbon budget doesn't come out quite as well as it does during the course of its operating life. But during the operating life of a nuclear power station, it produces huge amounts of electricity for very few carbon emissions. So yes, it's attractive for nations like ours trying to meet their carbon emissions targets. And so the work that we've been doing is have been trying to assess what kind of effects, any leaks from a nuclear waste repository

might be, you know, it'd be many hundreds of metres down to the surface and it would take a long time for anything to get to the surface. But if it did, we've been trying to answer the questions of whether it would have any effect on flora and fauna in thousands of years' time, if any of the radioactivity happened to get to the surface. So is it just something about humans that makes us particularly susceptible? because obviously it's Chernobyl if the animals and plants have sort of come back quite quickly. And I know like the Bikini Atoll as well. I know some of the coral reefs and the sharks there are looking all right, but humans can't go there.

So is it just something about our DNA that makes us susceptible to radiation? No, no, not really. And where humans aren't particularly more susceptible to radiation than other large mammals, but actually the regulatory regimes for them are. slightly different. And normally for the purpose is environmental protection. And this, you know, I'm not kind of all the legislation surrounding conservation is not really my area of expertise.

But I think it's fairly the same for the conservation of all sorts of organisms from all sorts of environmental pollutants. But for radiation, it's the case that what we're interested in is protecting the ecosystem and protecting the populations and the communities. protecting, you know, biodiversity and so on. And that's not quite the same as when you're trying to set up protection regimes for humans in which each individual matters. And so for regulating the kind of radioactive exposure of humans, it's normally regulated

that exposure won't cause any more than kind of one extra cancer in 100,000 or a million, something like that. Whereas when we're kind of protecting plants and animals, and so on, in general, what we're interested in is, is the community okay or is the ecosystem is okay? Have we affected biodiversity? And if we haven't, then it's fine. And sometimes that means that, you know, there might have been an individual plant or an individual animal that's been adversely affected. But if that doesn't affect the community at the moment, you know, legislatively, you don't have to protect every individual animal. You just have to collect the

community and the biodiversity. So for humans, often the levels are. set lower because we have to protect all individuals, not just the kind of communities or societies of humans. So just sort of one final question now. Obviously in the news, there's a lot at the moment about nuclear weapons. I think people are quite concerned about that. If there was sort of a nuclear bomb, then obviously in the direct sort of zone where that hit, that would obviously, like the plants and animals biodiversity there would be sort of wiped out straight away. But then as it sort of moved out, you'd find sort of fewer and fewer effects and then stuff would recover as well further out sort of quite soon, is that correct?

Yes, yes. And actually, in quite a lot of places, even if the kind of vegetation is completely raised to the ground and so on, often there's a seed bank buried in the soil and so on, and that gets irradiated, but a number of the seeds are still germinate and recolonise and so on. And so, I mean, a nuclear bomb right underneath the bomb, kind of the epicenter of the explosion,

the plants wouldn't survive. and actually they'd mostly not survive just because of blast damage and so on. And if an area is fairly radioactive, it takes a little while for the plants to recolonize and stuff. But they can recolonize more than you might think. Back in the 1960s, people did remarkable experiments where they put absolutely huge radiation doses in forests. And, you know, just as a point source. So it was radiating all around. and quite a bit of damage is caused very close to where these massive radiation sources are.

But as you go a bit further out, actually the plant communities in the ecosystem is often not as adversely affected as you might imagine from these huge sources of radiation. And so, you know, populations and communities of plants are relatively resistant and they resist the effects of huge forest fires and of droughts and all these kind of things. So the kind of communities and ecosystems of plants can survive remarkably well and can recolonise remarkably well, especially as seeds. You know, the seed banks relatively resistant to all sorts of environmental stresses. Yeah, I mean, I did read a thing recently about when the massive asteroid hit Earth and wiped out a lot of the dinosaurs, that a lot of seeds sort of buried underground and they sort of survived it as well, which is why sort of dinosaurs that could dig down were able to sort of get to the seeds

and things like that, and so they were the ones that eventually came birds. So I suppose it shows just how resilient that a seed is. You'd think it tiny and insignificant, but actually, if it can survive like an asteroid impact and radiation, then... Yes, I haven't heard that before about the seed bank and the dinosaurs and evolution of birds, but yes, there's a certain amount of sense in it. Seeds are kind of remarkably resistant to all sorts of environmental stresses, and you've probably seen that, you know, there are seeds that have been germinated

after they've been buried in peat bogs and all that kind of stuff for thousands of years. I mean, there's quite a lot of examples of seeds having survived over thousands of years in quite kind of inhospitable environmental conditions and then germinating again. I mean, they really are kind of a plants, really highly environmentally resistant way of traveling through space and time. So a seed is kind of quite a remarkable thing, actually, and does allow plants to resist all sorts of stress. is at kind of a community and ecosystem level, individual plants obviously get hit by some of the stresses and by wildfires and stuff. But the ecosystem as a whole quite often bounces back more than you might expect.

Yeah, I mean, I think the main thing to say really is that, I mean, of course, at very high dose rates, radiation has adverse effects. And kind of medium and some low dose rates, it can have effects on individuals. relatively low rate, but when you're protecting humans, that really matters. But chronic low doses of radiation to many animals and plants, we don't think, have the kind of level of adverse effects that some people have reported. Most animals and plants are remarkably resistant to the effects of all sorts of environmental stresses and quite often a chronic low dose of radiation doesn't quite have the same effect as people think. I think the good analogy to use is actually an allergy with electricity and everybody's quite happy to think that kind of a 1.5 volt electric shock, which is

what you get by putting your fingers either end of a battery, doesn't really do anything. But 50,000 volts will kill you straight away. And radiation is kind of the same, really high dose of radiation will have really profound effects and can kill you pretty quickly. But a very low dose of radiation is just like a low dose of a few millivolts or volts of electricity which we carry around with us all the time in our pockets and doesn't have much adverse effect. That was Professor Neil Willey from the University of the West of England talking about the effect of radioactivity on plants. Thanks for listening to the Science Focus podcast. In our January issue, which is on sale now, we report on a mission to visit the sun, Michael Mosley finds out whether dry January is worth it,

and we reveal the science of fighting facts. And of course, there's much, much more. Thank you for listening to the Science Focus podcast from the BBC Focus magazine team. We're the UK's best-selling science and technology monthly, available in print and in several digital formats throughout the world. Find out more at sciencefocus.com or look out for us in your app store. This podcast is sponsored by Name, Audio and Focal. The texture and emotional depth of music can be lost through digital sources or poor signal. Name Audio believes you can have.

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