Can genetics grow a better garden?

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0:37Hello and welcome to The Naked Scientist. This is the show where we bring you the biggest breakthroughs and talk to the major movers and shakers in the worlds of science, technology and medicine. I'm Will Tingle. This week we are here at the beautiful Cambridge University Botanic Garden to ask the question, can genetics grow you a better garden? All engine running. Absolute genius. Get this. Welcome. Welcome. This is the show where we bring you science. What that essentially means is... Discovery is... Advances. Questions. Research. Technology. Unbelievable. Without further ado, this is The Naked Scientist.

1:16It's been a blisteringly hot start to the summer across the Northern Hemisphere, and for those lucky enough to have one, the garden offers shade, colour, and a moment's peace. In skilled hands, which is to say, not mine, it can be a haven for biodiversity, a sanctuary for wildlife and a sea of calm in an otherwise frantic world. But like all delicate ecosystems, the garden is feeling the strain of drought, shifting seasons and the emergence of new pests and diseases. So can we turn to genetics to help our gardens adapt to these challenges? And to begin answering that, we start not in a flowerbed, but a 19th century monastery with a monk, some peas and the birth of modern genetics.

1:53I'm here with geneticist Erwin Scully at Cambridge University's Botanic Garden to explore the roots of garden science. It is a name I think many are familiar with, but perhaps maybe not entirely clued up on the inner workings of what he got up to. So to kick us off, who was Gregor Mendel? Mendel was the person who really unlocked the mystery of how genetic information is transmitted from one generation to the next. He was born in 1822 in Moravia, which is now part of what we would now call Czech Republic. Through some contacts he was able to get recommended to a position in the monastery at Brunn.

2:32And how he got into his particular research on plants, I suppose, is partly because of this interest that was already existing in understanding what were the factors that could help in developing and improving the development of agricultural crops. This was actually a focus of a lot of people, landowners and wealthy organisations that were interested in trying to develop their own economic output and developing the science of genetics from that perspective. But up until that point, no one had really understood the puzzle of actually what is it that causes the differences from one generation to the next.

3:10I believe you started, in fact, with chickens, but they proved to be a bit fruitless, and so we moved on to peas instead. In genetics nowadays, we have these species that we turn to when we want to do genetic studies where we know they have a short turnover, over a short genetic lifespan, as it were, so you can breed them quickly and you can observe phenotypes being passed on. You've got your bacteria, your Drosophila. Is there any reason why peas, do you think, were singled out? Are they particularly quick at reproducing? Peas were of interest for a few reasons. One was that you could grow them and they were relatively easy.

3:41They were amenable to study the kind of experiments and there were various strains that would grow well in the garden and at the monastery. They were an important agricultural crop and remained so and therefore they were of interest in their own right for that reason too. And I think it was something, he actually spent a couple of years before he started his experiments proper actually trying to identify the best strains of pea that would be amenable to the experiments that he had in mind. And he was looking in particular for the kinds of traits that you see in one strain and in another strain that when you could cross those two strains, you know, you could make progeny or a hybrid between one strain and another where you could compare these traits to things like the shape of the peas, the colour of them, the seeds that is, and also the various aspects of the plant itself, the height of it.

4:30So there was quite a lot of preparation and selection that went into actually deciding which strains he would use and what he would look for in his experiments. And he settled on peas, and as you say, the idea is to breed two together and see which particular traits were prominent in the offspring. and I don't think he quite had the concept genes obviously at that point in time so I think he referred to them as factors. He had these seven factors of what was being produced. So what were those experiments entailing and what did he really find? Yes, he set out it seems to understand, to try and crack this puzzle of why do we see when you cross two different strains sometimes you see the offspring look like one parent and sometimes the other and sometimes you see a mixture of the two and that was something that people had previously observed and it was well known that it wasn't just a straightforward blending of the parents.

5:25Some traits were like that but others were not. Mendel's real kind of insight that he brought to it was the application of statistical approach to this question. What he did was he was taking one parent from one strain and another parent from the other strain, crossing them. So in the next generation you had the offspring that he referred to as F1 And then he would go further, because people had done that before. But interestingly, he then took that generation and crossed it again with one of the two original strains. And that was where the important insights came from. Because then he saw that actually some of the original characteristics from the two original strains were either present or not present in certain proportions.

6:09And it took a little bit of logic and a little bit of reasoning to come up with a model for what might be happening. And you're right, he didn't have the concept of genes, or he didn't use that term, but he did, and his real insight was noticing that you could only get these kind of proportions coming through if you were essentially, in the process of reproduction, combining two discrete sources of information, which, as you say, he called factors or elements. By combining these two discrete pieces of information, that was what the new offspring was made from. And that really is the key insight into how genetics actually works.

6:44It's about transmission of information, not the sort of blending of forms. And it sounds like it's the precursor to understanding the concept of dominant and recessive genes, because he found this sort of almost perfect three-to-one ratio of certain factors turning up in successive generations, and then a quarter of them were different as well. So is that sort of what we see today when you study your GCSE genetics and you have dominant and recessive? Is that what he was getting at? Absolutely, that concept, which people had used before, again, the observation that some traits seem to be dominant over others, was again something that people had seen, but Mendel's model, you might say, was the first to really explain that in terms of an underlying mechanism.

7:27In fact, many of the concepts that we now use were indeed established by him in terms of the way that we talk about doing genetic experiments and looking at generations and combining progeny. also it's not just the fact that there's this notion of dominance and recessiveness it's also the fact that once you have this basis in information in these kind of packets of information, factors or elements then you can start to think about more complicated combinations of not just one but two and you can look at the joint inheritance of multiple different traits and he started to do that too in his experiments and that's what led subsequently to lots of research in understanding the kind of more complex traits that we see.

8:10And the field of genetics has done nothing but grow ever since. Eowyn, thank you very much, as usual. A pleasure to have you on. Thank you very much indeed.

8:27So if you want to create a more durable plant, that process starts at seed. Here at Cambridge University Botanic Garden, surrounded by rare trees and the hum of pollinators, it's easy to forget just how fragile plant life can be. As climate change, habitat loss and disease threaten species around the world, scientists are turning to a quiet but powerful tool, the seed bank. It's a kind of botanical time capsule. It stores the genetic future of thousands of plants to ensure that, whatever comes, each species has the best possible genetic diversity to grow from. Cambridge University Botanic Gardens' Angela Karno joins me in this glass house to talk us through what their seed bank is responsible for.

9:06Thank you for having me. Well, a seed bank is basically a place, a facility where we store seeds. And it can have multiple purposes and multiple sizes depending on why we want to store the seeds for. The seed bank here, very impressive and full of a wonderful collection of species. Obviously, it's a limited space. How do you decide which ones belong in the seed bank? It all depends on the needs of our garden, right? So there are different types of seed banks. For example, the Millennium Seed Bank is mostly for conservation of plants all over the world. But our focus is more on how to sustain our living collections.

9:48So that's actually the plantings that we grow. so whenever we go on expeditions we bring seeds from interesting plants that we collect and we process them we clean them and then we dry them and we put them in the seed bank until we are ready to propagate them so that those would be species from the wild but we also collect plants seeds from our plantings in the garden and that's in order to be able to propagate them in the future if let's say we lose one species or to share them with other botanic gardens yes i suppose that is the main point i feel that people realize about seed banks is that if something cataclysmic happens the entire species goes extinct you still have seeds of it at the very least yeah sure we can use our seed bank for that but actually seed seed banks like the millennium seed bank or other seed banks around the world that are aiming for conservation are in charge of that where seeds are actually frozen instead of just cooled down.

10:54In our collection the goal is if we lose a species not necessarily the whole extinction of the species but if we lose a plant of a species we can propagate it again from our seed bank. Is it also useful in kind of proving adapted traits if you You can prove that this specific individual of a species has good drought resistance. It's not as preyed upon by blight. You can then use that as a means of introducing that trait out into the wider population. Yes, well, when we collect seeds, we try to aim for a broad genetic diversity in the population we collect from. So, for example, if we realize that a given lot of seeds that we brought from a specific locality survives better in our conditions then we would use that more than another lot that may be suffered in in the conditions of cambridge uh so yes it's something that plays a role very important role the genetic diversity within a species and the different localities you can collect it from because some species have quite broad ranges and and so we can use that in our favor.

12:05One seed would probably go quite well here but if it's an area where you desperately need to reintroduce it to prop up a failing ecosystem the data here is probably not as useful as if it was you know say in a tropical jungle. Exactly you would need to be very mindful about where your plants where your seeds come from you don't want to introduce the wrong population if you want of a species in the wrong place if there are no other seeds of that species you might consider reintroducing it to a new locality but ideally you should collect you should use seeds that were collected from that locality to repopulate it.

12:48Without all that being said then are there expeditions being planned at this garden particular to sort of go out and perhaps build a seed bank with a more resilient attitude towards climate change coming down the line? Sure, we are focusing right now on places of the world that we know will currently have plans that in the future we will be able to grow because of the drier conditions in those localities. For example, we are now doing a series of expeditions to Croatia where the conditions are drier and plants grow that we can bring to our collections and potentially will thrive in the future here because of climate change and how the conditions will become drier here.

13:32But all the uses we have for our seeds are, for example, we get requests from researchers of the university or other institutions and they might need to grow plants for their studies or just use the seeds for different purposes. And so that's another use we have of our seed bank. generally sharing the seeds with other botanical institutions as well. And we wish you the best of luck. A pleasure to speak to you, Angela Karno.

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15:17Naked Scientist with me, Will Tingle. And this week we are asking if genetics can help grow a better garden. Now the engine of any garden is its pollinators. Organisms lured into a flower by the promise of a tasty treat and who leave, often unknowingly, with a dusting of pollen destined for another bloom. Pollinators come in many forms, birds, bats, even the occasional lemur. But by far the largest group is the insects. Insects rely on a mix of signals to decide whether a flower is worth visiting. Some are to do with smell, some even with electrical senses, and one of the most important is also visual.

15:50So important are these factors, in fact, that certain plants are simply less attractive to pollinators and get passed over. So what factors in a plant's advertisement system are the key to getting them back in the pollinator's good books? Well, with me in the garden is Beverly Glover, director of the Cambridge University Botanic Garden. Beverly, first of all, thank you very much for letting me crash at your place for the day. if I were a pollinator what are the most important things that I'm looking for when it comes to picking the right flower for me? Well you're looking for food and you're looking for advertising that tells you that that food is there so the first thing as you said is the reward something tasty to eat usually nectar sometimes pollard because it's quite protein rich occasionally other weird things oils resin scents but usually nectar and you need something you can see that you can learn to associate with the presence of that reward of course what you can see is going to depend on what sort of animal you are.

16:42Is this something that we can see with our human eyes or is this something that due to our evolution of the visible light spectrum is something that escapes us? So yeah it's very different for all sorts of different animals so we're standing here in the systematic beds at the Botanic Garden at the Boraginaceae family and we're looking at this cyanoglossum which is covered in bees and they are liking it because that purpley blue colour you can see is well cued to their visual system so bees have like us a trichromatic visual system we see red green blue they see green blue ultraviolet so it's different from ours it's blue shifted and this particular hue of flower is obviously very attractive and standing out to them but behind me on the next bed there's a bright red penstemon here it's got no bees on it at all if we have a look that will have plenty of nectar in it but the bees aren't seeing it very well because that red color doesn't pick up in their visual system it essentially looks muddy green to them that particular flower has evolved to signal to a hummingbird and birds have tetra chromatic visual systems so they see the red green blue that we see and the uv that the insects see and that is perfectly visible to them and they know that it'll have lots of nectar in it because big fat annoying bumblebees can't see it and won't have already got in there and drunk all the nectar up so if we wanted more bees to visit a plant is it in the realms of science fiction if we understand the genes that code for these molecules and these enzymes could we pop a couple in to therefore make a plant a bit bluer a bit more attractive to a bee so that's a good question people ask me this a lot because i work on the production of those diffraction gratings that make the blue color and i don't really imagine that i'm going to make you know iridescently blue oilseed rape and farba bean all around the countryside because actually the pollinators are particularly bees if we're talking about bees are quite smart so the key thing for them is the food if the nectar reward isn't there then you can make it look as pretty as you want but they won't stick with it they won't keep coming back to it and you won't get pollination so in the work i do with crop pollination the focus is first on what's the reward we've been for instance exploring different farba bean varieties and cultivation in the uk looking at which ones make the most nectar and the most sugar rich nectar and that's got to be the starting point because this is a smart animal it'll learn what's good for it once we've got that right yeah we can make it a little bit more interesting we can think about the size of the flower and the length of the the tube that the nectar's in and the colour of it and you know blue wouldn't hurt but it's it's sort of the icing on the cake it's a clever animal in the end i would say unless well most of your listeners i hope are smart enough to buy the product they want however good or bad the advert is the advert might catch your eye in the first place but it's the product that matters no comment so therefore is it as you said if we're looking to use genetics to improve a plant and improve its relationship with pollinators are we therefore looking for the pathways to create a better meal for the bee instead yeah and it's not just about the quality of the meal it's about the energy you expend getting that meal out as well so it's about energy gained for energy spent so part of that's about the reward how sugar rich how much of it but it's also about how hard is it to get into the flower so if you think about something like a snapdragon flower there the dark pink one over there or the yellow ones behind only a heavy bumblebee can actually open that flower and so if what you wanted was to attract honeybees to those flowers you'd have to do something to make them less difficult to get into a honeybee will spend an awful lot of time we can watch the hover flyers indefinitely and they'll never figure it out they're not smart enough so they're wasting energy unable to access the flower whereas a bumblebee lands on it the lip opens and it gets into the nectar that's actually an evolutionary advantage for the flower and for the bumblebee because again as with the red flower we talked about earlier the bumblebee knows that that snapdragon is likely to be nectar rich because he knows that hoverflies and everything else can't get in but if we wanted to think about how to improve the attraction to flowers not just the reward itself but also how much energy you spend getting to it so you can think about how you open the flower does the flower provide grip so if it's slippery and difficult to access that makes it more energetically inefficient if you provide conical type cells on the surface that the insect can get a grip on like you might on a climbing wall that reduces energy expenditure if you make the tube length such that you don't have to you can literally just land and drink rather than land and have to crawl and wiggle your way around thinking back to visual cues things like nectar guides so lines or spots or a bullseye pointing to where the nectar is can make the difference between taking three seconds to land in the right place and two seconds to land in the right place and if you're visiting a hundred flowers then that's a lot of seconds of energy spent flying So all of these things help maximise the energy reward in exchange for the energy spent getting it.

21:18If we're looking to create this ultimate energy efficient garden then for our pollinators, is this something that is as simple as selective breeding, do you think? Or is this something that requires a bit more of a modern genetic toolkit? Well it can be done with selective breeding. I mean gardeners and plant breeders have been breeding for the horticultural industry for centuries and have produced all sorts of different colours and combinations and patterns, some of which you'll see in your own garden are really attractive to pollinators and some of which aren't. Of course, knowing a little bit about the genetics and how these things are built, the developmental biology of these traits makes it much easier for us to identify where we should be focused.

21:52But I think the thing is, I'll bring you back and say, I don't think there's ever going to be a perfect flower because there are hundreds of thousands of different pollinator species. So actually what suits a bumblebee isn't what suits a hummingbird, is not what suits a hoverfly. And if we want to keep that range of pollinator species alive and well, then we're going to need a range of different flower types. I would be remiss as a final question then, given that you are the director of this wonderful garden, not to ask if the listeners at home, as you said, wanted a good, vibrant garden, keeping pollinators well fed.

22:22Is it about that diversity, do you think? There's no one shoe size fits all type thing. It is all about that diversity. Yes, absolutely. And the one key thing I'd ask people to think about, which people tend to forget, is the time at which the plant flowers. So diversity of flower types, but you've got pollinators foraging from March, when bumblebee queens hatch, all the way through to October, November. And so you want plants in your garden that produce food for that entire duration, not just we're all very good in the UK at May and June looking gorgeous in the garden and the rest of the year it being a bit dry and sad.

22:55Try to think about things that will give you flowers for that whole duration. Lovely. Thank you very much indeed. So far this episode, we've looked at how seed banks can keep our species genetically diverse and how to make plants more appealing to pollinators. Our final consideration in creating the plant of the future is how to make the plant itself hardier. Are there steps we can take or genes we can tinker with that would allow vegetation to be inherently better prepared for the oncoming climactic challenges? Ian Henderson at Cambridge University is at the forefront of plant genetics. So who better to ask about making a hardier plant?

23:27And he joins me now. Pleasure to have you in the garden, Ian. To kick us off, could you outline what challenges we anticipate will hit plants the hardest in the near future? Well certainly the changing climate is a big one so higher temperatures, more unpredictability in weather, drought and also changing climate changes many other things including pathogens and pests. And so a lot of things have the potential to change quite quickly so a big need to further adapt crops and plants and genetics is one way to do that. Yes, Gregor Mendel, many centuries ago, had the luxury of time when breeding his peas together to get a more useful product.

24:08If there's limited time, if we take drought for an example as the first one, how do you go about making a more drought-resistant plant? Well, you know, obviously if you think about plant diversity, there are plants that grow in extremely arid conditions. Cacti are naturally adapted to low water availability. They're not great to eat, though. so really it's trying to understand what are those adaptions and can you take some of those adaptions to dealing with low water availability and put them into crops there are lots of things that are known like the hormone abscisic acid is well known to to be involved in in how how plants respond to drought recent decades the receptors for those hormones have been discovered other things like c4 photosynthesis you may have heard of there's a big project involving people in cambridge julian hibbard trying to engineer c4 photosynthesis into rice now that's a photosynthetic trait but it has a big effect on on how well water is used as well so there are lots of lots of potential pathways one could could use that our understanding of but it's still it's a lot of hard work actually translating these things into a crop context it's still extraordinary to me that you can take a drought resistant gene in one plant and somehow splice it into a completely different family of plants that doesn't sound like a simple process to me at all no it's not and if you're taking a gene from a very different plant and putting it into a crop there's lots of questions about you know what promoter is suitable for expression which cell type do you want this gene to be expressed in at what level how stable is it from generation to generation does it become silenced for example these are all difficult things people can have a very brilliant idea but then actually executing it and translating it is really hard work but achievable it sounds like you've made good sounding strides in the genetic enhancement in terms of drought but is there a similar progress in pest control that sort of thing i mean absolutely since sort of the 1990s there's been tremendous progress in the genetic understanding of plant immunity now they don't they don't have like an antibody-based system like we have but they have actually some uh they're types of receptors called resistance genes that are part of an ancient family that's shared with animals so things like the inflammasome but you could this is a major part of the plant immune system.

26:42And the way it works is you have these single resistance genes that are able to recognise particular strains of pathogens and have a kind of gene-for-gene immune response. So people like Jonathan Jones at the Sainsbury Lab in Norwich have done really striking experiments taking a single blight-resistant gene from wild potatoes in South America, put that into a conventional UK agricultural variety, and you know in the fields you have complete resistance against blight and it's a black and white effect in the field and if you think about if you didn't do that what you would have to do you're talking about a lot of spraying chemicals which are expensive and also not really that green and so in this case i'd say it's a very simple genetic change achieved as a gmo that has a much more sustainable outcome for agriculture and to me it's just a no-brainer if it was properly regulated what you've outlined is fantastically encouraging and like a really really interesting if we do manage to surmount these ethical political hurdles are you optimistic for the future of plant security and crop growth and that sort of thing in the face of this monumental shift that is climate change?

28:03I think so. I mean, for millennia, as I mentioned earlier, humans have been breeding and adapting crops very effectively, essentially transforming very inedible varieties to the crop that we eat on a daily basis. And that was done without any formal understanding of genetics or inheritance, really, apart from presumably some concept of, you know, if I keep the seed from this plant that did well then it's likely to do well in the future and that was achieved over millennia now we have the ability to sequence not just one crop genome but all the varieties of a crop and related species so you have this kind of pan genomic information that helps you really understand which genes control which traits and then we have these tools like agrobacterium transformation and CRISPR, as well as lots of other emerging technologies that give us really pinpoint precision, ability to manipulate specific genes or pathways.

29:11And so I'm very optimistic that solutions will be found. I think it will likely get worse. And as the situation gets worse, it will become a necessity to use these technologies rather than a kind of luxury. But we have decades of knowledge now on what the key pathways are. I think we'll be ready. A positive note to end on then, Ian. Thank you so much for joining me. So all the gardening tools exist, it seems, to ensure that gardens around the world can stay in bloom. But as Ian outlined, we await to see if there's sufficient urgency and legislative courage for this range of genetic conservation methods to revolutionise this field.

29:51thank you very much to all my guests and a huge thanks to cambridge university botanic garden for hosting me next week we stay with genetics as chris smith looks at 25 years of the human genome project what is it what has it achieved and what is it yet to deliver the naked scientist comes to you from the university of cambridge's pace it is supported by rolls-royce i'm will tingle and from everyone here at the naked scientist thanks for listening and until next time goodbye

30:36We'll be right back.

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