1 00:00:00,000 --> 00:00:05,000 Hello, my name's Lindsay Turnbull and I'm an associate professor in the Department of Plant Sciences 2 00:00:05,000 --> 00:00:10,000 at the University of Oxford, and we're right in the middle of this very serious corona virus crisis right 3 00:00:10,000 --> 00:00:15,000 now. And my students are all stuck at home and we want to keep them in touch with biology 4 00:00:15,000 --> 00:00:21,000 and keep in touch with us. And so we're going to make a new series of videos and they're going to be called back garden 5 00:00:21,000 --> 00:00:45,000 biology. 6 00:00:45,000 --> 00:00:50,000 Well, welcome to this week's episode. I'm going to be looking at this flower, 7 00:00:50,000 --> 00:00:55,000 not the primroses underneath, which is where I started this series, but at these purple flowers 8 00:00:55,000 --> 00:01:01,000 that are hovering above them. The primrose is just seated themselves into this bit of lawn. 9 00:01:01,000 --> 00:01:06,000 But I actually planted a little dry, fragile bulbs of these 10 00:01:06,000 --> 00:01:11,000 four artilleries myself. And these are now a few years old and they're thickening up nicely 11 00:01:11,000 --> 00:01:17,000 and they're just growing in the grass and they're quite happy to do that. The proper name is a snake's 12 00:01:17,000 --> 00:01:22,000 head for artillery, and that's the county flower of Oxfordshire. So they're 13 00:01:22,000 --> 00:01:27,000 quite common in Oxfordshire. You find them growing in very wet meadows. This part of the lawn 14 00:01:27,000 --> 00:01:32,000 is quite where to me. I'm pretty happy here, although it's not a proper water meadow. So they're not as fussy 15 00:01:32,000 --> 00:01:37,000 as that sometimes made out to be. The colour is, well, not 16 00:01:37,000 --> 00:01:42,000 everybody's cup of tea. They've often been described as mournful and melancholy. And that 17 00:01:42,000 --> 00:01:48,000 used to be one of their traditional names, the melancholy fairy. They've even described as 18 00:01:48,000 --> 00:01:54,000 Fergus purple colours, not to everyone's taste. If you look inside them, you can see the classic 19 00:01:54,000 --> 00:01:59,000 arrangements of anthers and the stigma in the middle and the bees 20 00:01:59,000 --> 00:02:04,000 like them. So they do get visited by my pollinators. Now, this is the normal 21 00:02:04,000 --> 00:02:09,000 form, the purple form. But if we move sideways a little bit, you'll see 22 00:02:09,000 --> 00:02:14,000 there's a light form there. And in every population of snakes had 23 00:02:14,000 --> 00:02:19,000 fraternities, there are always white ones. Perhaps 10 or even 20 percent of the flowers 24 00:02:19,000 --> 00:02:25,000 are white. Now, that's pretty unusual, 25 00:02:25,000 --> 00:02:30,000 actually. It's not that uncommon to occasionally have a white form of some 26 00:02:30,000 --> 00:02:35,000 plants. But to have it at such a high frequency, to have 10 or 20 percent 27 00:02:35,000 --> 00:02:40,000 of them be white, that requires a special explanation. So we're 28 00:02:40,000 --> 00:02:45,000 trying to understand how the white fertility is able to persist at around one 29 00:02:45,000 --> 00:02:50,000 in 10 individuals. Well, that's my estimate for my own garden. And to understand that, we're 30 00:02:50,000 --> 00:02:56,000 going to have to think about its genetics and to understand that I'm going to start with some Lego. 31 00:02:56,000 --> 00:03:01,000 This is a Lego spaceship from the Star Wars series that my son made. And 32 00:03:01,000 --> 00:03:10,000 we bought him a kit and the kit came with all the bricks inside and an instruction manual. 33 00:03:10,000 --> 00:03:16,000 And here's the instruction manual. And this tells you exactly how to put all the bricks together 34 00:03:16,000 --> 00:03:21,000 so that you can make the starship that you want and organisms, whether they're humans or 35 00:03:21,000 --> 00:03:26,000 fertilises, also have an instruction manual. We can't see it, but it's inside 36 00:03:26,000 --> 00:03:32,000 them and it's inside their cells and we call it a genome. And what's unusual 37 00:03:32,000 --> 00:03:37,000 about the instruction manual, the genomes of most organisms is it's actually doubled up. 38 00:03:37,000 --> 00:03:42,000 So you actually have two copies of the manual that work together seamlessly. 39 00:03:42,000 --> 00:03:47,000 And you've got one copy of the manual from one of your parents and you got the other copy from the other parent. 40 00:03:47,000 --> 00:03:52,000 And that's exactly the same for the fraternities. All right. So you have two copies 41 00:03:52,000 --> 00:03:57,000 of the instruction manual. That means you have two copies of every single instruction. And 42 00:03:57,000 --> 00:04:02,000 the single instructions are called genes. And I want to think about that gene that 43 00:04:02,000 --> 00:04:07,000 makes the purple pigment that makes those flowers purple. So let's focus 44 00:04:07,000 --> 00:04:13,000 in on that. So I'm going to imagine that 45 00:04:13,000 --> 00:04:18,000 this is what the instructions, the genes look like for the purple individual. So they have 46 00:04:18,000 --> 00:04:23,000 two copies of an instruction or a gene that makes that purple pigment 47 00:04:23,000 --> 00:04:28,000 and they have two copies of that one from each parent. Now, sometimes when individuals 48 00:04:28,000 --> 00:04:34,000 are born, there are mistakes in one copy of the manual. Mistakes just arise all the time 49 00:04:34,000 --> 00:04:39,000 we call those mutations. This mutation is called a loss of function 50 00:04:39,000 --> 00:04:44,000 mutation because this gene doesn't work anymore and it can't make the purple 51 00:04:44,000 --> 00:04:49,000 pigment. That might not be too bad for this individual because it still has a copy of the gene 52 00:04:49,000 --> 00:04:55,000 that does allow it to make the purple pigment. So it may look entirely normal. We sometimes call 53 00:04:55,000 --> 00:05:01,000 these individuals carriers that carrying broken genes, but they don't have any visible effect. 54 00:05:01,000 --> 00:05:06,000 But those individuals may be passing on genes, which means that sometimes an individual 55 00:05:06,000 --> 00:05:11,000 is born with two broken copies of a gene and that can be very serious for 56 00:05:11,000 --> 00:05:17,000 that individual. In this case, what it might mean is that the fraternity is white 57 00:05:17,000 --> 00:05:22,000 because neither copy of that gene can make the purple pigment and say that the 58 00:05:22,000 --> 00:05:27,000 flower ends up white. Now, what about the fitness of these individuals? How successful 59 00:05:27,000 --> 00:05:32,000 are they going to be? Well, if the red and the purple white were exactly the same 60 00:05:32,000 --> 00:05:38,000 fitness and that and these ones always looked purple, then we'd actually expect the 61 00:05:38,000 --> 00:05:43,000 white ones to fit around 25 percent. That's a bit too high. I don't think they're quite as common 62 00:05:43,000 --> 00:05:48,000 as that. More like 10, which suggests that the white ones are not quite 63 00:05:48,000 --> 00:05:53,000 as successful as the purple. So that's why push them down a bit. Perhaps they don't produce as many seeds. Perhaps 64 00:05:53,000 --> 00:05:58,000 they don't attract as many pollinators. And if that's true, actually, we would 65 00:05:58,000 --> 00:06:03,000 expect the white one to become really quite rare, because every time there's two copies of the of the 66 00:06:03,000 --> 00:06:09,000 non-functional gene together, that individual doesn't do very well. So those genes are not passed 67 00:06:09,000 --> 00:06:15,000 on. So it's a little bit too high frequency to imagine that this is what's happening. 68 00:06:15,000 --> 00:06:20,000 So the key to this lies in these individuals, in the carriers. So we seem to hear that 69 00:06:20,000 --> 00:06:25,000 they are just as good as the individuals who have two copies. It 70 00:06:25,000 --> 00:06:30,000 may be that they're even worse, that they have a disadvantage, in which case this non-functional 71 00:06:30,000 --> 00:06:36,000 gene will be lost very rapidly from the population. And these individuals will be really rare. 72 00:06:36,000 --> 00:06:41,000 But just sometimes, these Kariya individuals can actually be more 73 00:06:41,000 --> 00:06:46,000 successful than the individuals with two functional copies of the gene. And you may know 74 00:06:46,000 --> 00:06:51,000 the condition in humans called sickle cell anaemia. When this happens, it's 75 00:06:51,000 --> 00:06:57,000 the haemoglobin gene, Notter Purple, which is still a pigment gene, but something that's very important in humans for carrying 76 00:06:57,000 --> 00:07:02,000 oxygen around the body. And if you live in an area with lots of malaria, then having 77 00:07:02,000 --> 00:07:07,000 a normal haemoglobin gene and one sickle cell gene can protect you against malaria, 78 00:07:07,000 --> 00:07:13,000 despite the fact that you get two copies of the break, Gene, you're really in trouble. 79 00:07:13,000 --> 00:07:18,000 And so it's entirely possible, although I have no idea. And I'm just guessing that this is what's 80 00:07:18,000 --> 00:07:23,000 happening with the snakehead fertility. Perhaps those individuals with one functional gene or one 81 00:07:23,000 --> 00:07:28,000 broken gene are actually more successful than those ones. And if they are, then they 82 00:07:28,000 --> 00:07:34,000 would be able to maintain the white fertilises as a higher frequency in the population. 83 00:07:34,000 --> 00:07:39,000 And this is just a general mechanism that can go on. Nobody's studied the flotilla is well enough to know 84 00:07:39,000 --> 00:07:44,000 about what's happening here. Okay, well, we're going to go back outside and 85 00:07:44,000 --> 00:07:51,000 think about a second mechanism that might also maintain those white for tanneries. 86 00:07:51,000 --> 00:07:56,000 The second explanation about why those wait for artilleries are able to persist at quite high 87 00:07:56,000 --> 00:08:01,000 frequency. We need to think hard about what that purple pigment that the purple for terrorism 88 00:08:01,000 --> 00:08:07,000 making really does. And it is a type of pigment called an MFA on. 89 00:08:07,000 --> 00:08:12,000 And most plants produce those. And this Aissa is an example of a plant that's producing it 90 00:08:12,000 --> 00:08:17,000 right now. And I hope you can see that the leaves are not green. These are the brand 91 00:08:17,000 --> 00:08:22,000 new leaves coming out in spring. And they're heavily tinged with reddish purple 92 00:08:22,000 --> 00:08:27,000 colour. And that is caused by ANFO silence. And if you look around your garden 93 00:08:27,000 --> 00:08:33,000 now, lots of plants that are putting out new leaves, whether it's paeonies roses, 94 00:08:33,000 --> 00:08:38,000 they're often very heavily red and purple. They don't really look green at all. Some of them, 95 00:08:38,000 --> 00:08:44,000 why are they producing those pigments which are probably expensive for the plants to produce? 96 00:08:44,000 --> 00:08:49,000 Well, it seems that they have some protective function. They can protect the new leaves against all 97 00:08:49,000 --> 00:08:55,000 kinds of things. Frost, for example, which can happen later in the year unexpectedly, 98 00:08:55,000 --> 00:09:01,000 but also damage by insects and pests, possibly even diseases. 99 00:09:01,000 --> 00:09:06,000 So once we know that, that might help us to understand that patellar is a little bit better. So I'm just 100 00:09:06,000 --> 00:09:11,000 going to go next to those now and have a think about that. 101 00:09:11,000 --> 00:09:16,000 So these purple for Artillery's, the purple colouration is not confined to the flower. I won't 102 00:09:16,000 --> 00:09:21,000 try to zoom in on this too much, but this stems because it's difficult to see. But 103 00:09:21,000 --> 00:09:26,000 the stands are also quite heavily purple. Whereas the white one doesn't 104 00:09:26,000 --> 00:09:31,000 have any of that. So it just can't produce those anthocyanins, it seems. 105 00:09:31,000 --> 00:09:37,000 So the question is that could be a benefit to the white ones. The anthocyanins are expensive 106 00:09:37,000 --> 00:09:42,000 to produce. So if it doesn't produce them, it might actually be more successful than the purple 107 00:09:42,000 --> 00:09:47,000 ones. But that might only work when it's red. Okay. 108 00:09:47,000 --> 00:09:52,000 And if we just take a look at the whole population now, imagine that the purple 109 00:09:52,000 --> 00:09:58,000 ones, because they're producing the signs, are resistant to a pest or a disease 110 00:09:58,000 --> 00:10:03,000 that might sweep through that population. And the white one at the moment, because there's only one 111 00:10:03,000 --> 00:10:08,000 of it can hide amongst these resistant ones. It's benefiting from something 112 00:10:08,000 --> 00:10:14,000 that we call herd immunity. And you might have heard a lot about herd immunity in the context 113 00:10:14,000 --> 00:10:19,000 of the corona virus. Now, the problem for the white one is that, okay, at the moment 114 00:10:19,000 --> 00:10:25,000 it's fine and it might even be doing better than the purple ones. And it's frequency might then increase. 115 00:10:25,000 --> 00:10:30,000 But if it increases to March, you'd have a lot of white ones and only a small number of purple 116 00:10:30,000 --> 00:10:35,000 ones. And the herd immunity is now lost and a disease or a pest might sweep through 117 00:10:35,000 --> 00:10:41,000 that population and kill all the white ones or severely damage them. And so 118 00:10:41,000 --> 00:10:46,000 you get this thing called frequency dependent's. When the white one is rare, it might 119 00:10:46,000 --> 00:10:51,000 have an advantage, but if it becomes too common, it then gets a disadvantage. 120 00:10:51,000 --> 00:10:56,000 And that is a general mechanism that can keep a second type of individual 121 00:10:56,000 --> 00:11:01,000 in a population at a low frequency. And that might be what's going on with these 122 00:11:01,000 --> 00:11:06,000 white fertilises. I honestly don't know because I don't think anyone's studied it carefully enough, 123 00:11:06,000 --> 00:11:12,000 but it's definitely a possibility. So let's look at the population again and just think about that herd 124 00:11:12,000 --> 00:11:17,000 immunity concept, because you're probably hearing a lot about the white vulnerable individual 125 00:11:17,000 --> 00:11:22,000 here can benefit from the herd immunity. Now, we as a population are like we're 126 00:11:22,000 --> 00:11:27,000 like a big population of white for is at the moment. None of us have ever had corona virus. We're 127 00:11:27,000 --> 00:11:32,000 all vulnerable. But as that disease comes through the population and you can imagine 128 00:11:32,000 --> 00:11:38,000 the white fertilises turning purple as people get the disease recover 129 00:11:38,000 --> 00:11:44,000 and become resistant. And that's what we're trying to build in the population. We're hoping 130 00:11:44,000 --> 00:11:49,000 that enough of us get it and recover from it and become resistant, that we 131 00:11:49,000 --> 00:11:54,000 can offer protection to the very vulnerable to the white fatalities amongst us who 132 00:11:54,000 --> 00:11:59,000 perhaps just aren't are so vulnerable, because if they got it, it'd be so dangerous 133 00:11:59,000 --> 00:12:04,000 for them. And the government initially decided they'd just try to let that thing happen naturally. The 134 00:12:04,000 --> 00:12:09,000 problem for us with Corona virus is it's too dangerous even for people who are 135 00:12:09,000 --> 00:12:14,000 apparently healthy. You just can't know if you get it. Will you just recover and 136 00:12:14,000 --> 00:12:19,000 be fine and now resistant or will you end up in hospital? And so they're having to manage 137 00:12:19,000 --> 00:12:24,000 the course of this disease, keep us at home, try to delay the transmission 138 00:12:24,000 --> 00:12:30,000 so that the NHS can actually cope with the number of sick people. But in the end, that's what we want to do. 139 00:12:30,000 --> 00:12:35,000 And, of course, the very best way to build resistance and turn us all into purple for Artillery's is 140 00:12:35,000 --> 00:12:40,000 to have a vaccination that is by far the safest way to have herd 141 00:12:40,000 --> 00:12:46,000 immunity in a population. So let's all keep our fingers crossed for all those hardworking people 142 00:12:46,000 --> 00:12:51,000 out there who are trying right now, including some of my colleagues at Oxford University, to develop 143 00:12:51,000 --> 00:12:56,000 a safe and effective vaccine. So just to finish, what can you be looking out for in your garden 144 00:12:56,000 --> 00:13:02,000 this week? We'll have a look around, and I bet you'll be able to find quite a few white versions 145 00:13:02,000 --> 00:13:09,000 of various common plants in my garden. There are white Forget-Me-Not. 146 00:13:09,000 --> 00:13:15,000 In amongst the blue ones, there are white snakes at facilities and amongst the purple. 147 00:13:15,000 --> 00:13:21,000 And there are white bluebells in amongst the blue ones. Gardeners 148 00:13:21,000 --> 00:13:26,000 really like having unusual colours of plants and those loss 149 00:13:26,000 --> 00:13:31,000 of function mutations that knock out the unthaw signs are quite common, 150 00:13:31,000 --> 00:13:36,000 creating white forms of different flowers which gardeners then seise upon and grow. 151 00:13:36,000 --> 00:13:41,000 If you're really lucky, you might find an even more unusual colour mutant. And some people have made a lot 152 00:13:41,000 --> 00:14:00,040 of money out of that by then selling it to the garden industry. So worth keeping your eyes peeled.