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cc >> Good evening, everyone. I'm Cassie Immel from the UW Biotechnology Center. This evening we have William Tracy who's a professor and chairman from the Department of Agronomy here at UW Madison. Bill received his bachelor's of science and master's in science in plant science from University of Massachusetts, Amherst and his PhD in plant breeding from Cornell University. Following graduation, he worked as a corn breeder for International Plant Research Institute and Cargo Incorporated. In 1984, Bill joined the Department of Agronomy as an assistant professor and sweet corn breeder. Bill leads one of the few remaining public sector sweet corn breeding programs in the US, and a number of inbreds and hybrids developed by his team are actually grown on every continent with arable land. Since moving to Madison, Bill has taught agronomy 100, principles and practices of crop producion, and many other undergraduate and graduate level courses. Since 1994, he has taught a course on using corn in the K-5 classroom as part of the Wisconsin Teacher Enhancement and Biology Program. And tonight he'll be discussing what sets plant breeding apart from other technologies and why it's so powerful and creative in the world today. So without further ado, here's Bill Tracy.

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>> Thank you, Cassie, and thanks for all of you coming out tonight. I'm going to talk to you about two of my favorite topics, a little bit mashed up because I basically gave the organizers two different titles. So I want to make sure I do honor to both of them. I'm going to talk about my favorite topic which is about plant breeding, and plant breeding is a unique and special technology. It's actually an incredibly old technology. It goes back 10,000 years. And it's very different from most of the other technologies that we employ. And I'll talk to you about that and talk to you about why it's important. And then I want to talk to you a little bit about breeding better sweet corn. As you heard, this is my 30th anniversary on the Madison campus, and I've been breeding sweet corn for 30 years. We've got a brand new type of sweet corn, and we're doing a lot of other things with sweet corn as well so we'll get into that toward the end. So what I want to first talk about is Charles Darwin's really great insight. And that is the diversity of life, and I don't get to show many, I'm an agronomy professor so I don't get to show many sea dragon pictures, so I always use this slide for this purpose, the diversity of life is due to the creative power of selection, both natural and artificial. And of course we have an example of corn up there in the corner, which is an artificial and natural selection, and all of these other organisms that are the result of natural selection. The creative power of selection is actually a bit different than what most people think about when they think about evolution. It's really easy to think about a variable population of individuals and we select out the best ones and the new population will be different, but there's nothing really new in the new population. It's just the best ones from the previous population. But what evolution actually does is create new things that actually never existed before. And I think a lot of biologists actually miss this point. What Darwin recognized and plant breeders harness is the creative power of selection. And he based a lot of his work on the work of animal and plant breeders. The point really here is that if selected plants are allowed to sexually reproduce and non-selects are not, so we get rid of the ones we don't want, allow the ones that we do want to reproduce, the allele frequencies, the gene frequencies will shift in the direction that we want them to shift to. So that's pretty much easy to understand. Thank you, Cassie. If the process is repeated for a number of generations, then favorable alleles at many loci affecting the selected trait, many genes, so many genes are in play here, will accumulate in the population. Through sexual reproduction, these loci, these genes, will be recombined often resulting, and this is the key point, in completely novel and unexpected phenotypes. Phenotypes are how individuals look. I'm looking at a bunch of phenotypes in the room here right now, and many of them very fine phenotypes, I might say.

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But really, and as a plant breeder, and I know I have some plant breeders in the audience as well, as a plant breeder one of the most amazing things to me is to walk out into that field and see things that I never could imagine could exist. We get completely novel things because of this process of sexual reproduction, selection, and repeated genetic recombination. So Darwin's great insight is the key, and I have mostly female grad students so I will say the key is women's power of accumulative selection. Nature gives successive variations. Women add them up in certain directions useful to her, and in this sense she may be said to make useful breeds. And I would point out, and this is where I'm going with this part of the talk, when early civilizations of humans started breeding wolves, started selecting wolves, they never expected to see anything like that. That's not what they were doing. That came about through this process that I'm talking about. So plant breeding has been a highly successful technology for 10,000 years. Our food supply depends on it. Selection based on the phenotype, and the phenotype means the appearance, selection based on the phenotype has been the key feature of plant breeding programs for most of those 10,000 years. There's been many different ways of selecting. I'm not going to go too deeply into those. Today, and only in the last maybe 30 years, 20 years, have we actually developed molecular tools that now allow us to select directly on the genotype. The genotype is the gene sequence as opposed to the phenotype which is the appearance. I contend, and it's part of my point here, that we really don't want to let go too far of that phenotype because the phenotype, selection of the phenotype is what gives us incredibly creative results, if you will. So selection with recombination. Its direct effects are remarkably precise and predictable and powerful. I'm going to show you data that shows if we select for a certain trait, it's incredibly easy, at least in corn, which is a good organism for this but it's true of other crops as well, it's remarkably precise and predictable. This is, by the way, the ancestor of corn up there. That's teosinte. This is what early Americans would have found 10,000 years ago growing in Mexico. It's essential inedible, but that is where corn came from. So selection is predictable, yet the genetic and physiological mechanisms are often, mechanisms of change are often unexpected and novel. And this change creates new and novel phenotypes. So you can imagine yourself being a first American somewhere in Mexico, selecting, this is teosinte, selecting for teosinte that would be edible, something that you could actually eat, and they had no idea that that's what they were going to get. Now, it took a couple of thousand of years to get there, but selection got there. The folks who did that at the beginning had no idea what they were going to get. So it creates new and novel phenotypes that I will contend are beyond human imagination. So I'm going to talk about recurrent selection, which is one of these plant breeder tools that I talked about, and with recurrent selection we improve the population. Kind of the scientific definition of recurrent selection is to improve the population while maintaining genetic variation. And I'm going to talk about a specific kind of recurrent selection which is divergent recurrent selection. So this is some of my work I'm going to talk more about this in depth. This axis, which unfortunately is not labeled, is the leaf number. And so this trait, again I'm going to go into this more in a minute, this trait, the initial cycle, what we call cycle zero, was here which has about eight and a half leaves. And we exerted a forward selection pressure, and again I'll go into this in more detail, we exerted a forward selection pressure, and after a number of cycles, we moved the number of leaves in this direction, in this divergent direction down to about four, and in this direction we moved it up to about 18 after only 11 cycles. And, again, when I show you the actual data, it should ring more true to you. We're now, and the cursor here doesn't go that far, we're now out at cycles 15 or 20, 15 or 18, and we've already hit the maximum number of leaves. So we've pushed these populations, diverged them into two different directions. And in these studies we generally select just a single trait. We concentrate on one thing, and then the changes in that single trait are what we call the direct effects. But then the interesting thing, and I hope you'll find it interesting after I go through this, is that there are a number of indirect effects. So we make the plant have more leaves or less leaves. How does the plant respond in other ways? And the plant is going to respond in other ways. One of the things I like to say about plant breeding in general is that plant breeding is a compromise. In the case of sweet corn, sweeter sweet corn, more tender sweet corn, that's what people want, but sweeter sweet corn and more tender sweet corn does not germinate as well. So we have to compromise between germination so the plant actually responds to our selection. Now, I have a couple of words down here. So if we see an indirect effect, it could be due to a number of things. Physiological interaction. I'm going to give you an example of that so I'm not going to define that now. Pleiotropy. Pleiotropy is actually where the gene is affecting two things. So we're driving gene frequency for a certain trait in this direction, and that gene also affects something else. Also, linkage. Linkage, of course, is where two genes are linked. So we have two genes closely linked to one another. We're driving one of the genes that affects leaf number in this direction and the other linked gene is changing in response of the frequency. And then finally drift, which is just a random change that probably you could call it an artifact or a mistake during the selection process. So we can find these differences and look at them. So I'm going to give you three, maybe four, examples of selection of divergent. This one actually is not divergent selection, but this is a fascinating study. It's selection for prolificacy. Prolificacy is the number of ears a corn plant has. The ears, of course, are the female flowers or the female inflorescence. And here we see, down at the bottom, this would be considered a prolific plant because it's got two fully formed ears, and this would be a non-prolific plant because only the upper ear is fully formed. So in this study, which was started by John Lonnquist, a faculty member here many years ago, continued by my colleague who is now retired, Jim --, and then continued by my new colleague Natalia de Leon. This selection has gone on for over 30 years at this point. It's probably closer to 40 at this point. So selection was simply for the number of ears per plant. The plants that had more ears were the ones that actually were able to contribute their genes to the next generation. So selection, in this case, was done before pollination because you can see how many ear shoots there are, and this allowed biparental control, which means we can control the female because those are the plants where the ears are and we can control the male by removing the tassel from the plants that we didn't want. So we're getting both male and female control there. And this results in faster gain. We're going to get better gain. You can imagine that would be true, as opposed to these ears being pollinated by everything in the field. So evaluation of progress is done at different planting densities. So this is the direct effect of selection. You can see that over time the number of ears per plant has increased. Oddly enough, and I actually don't know why this is, one of the most frequent questions I get from people when I tell them I'm a corn breeder is they say, how many ears does a corn plant have? I don't know why that's compelling. But in fact, a corn plant generally in a farmer's field will only have one ear, but if a plant is planted with no competition, they could have, I've seen plants have up to 30 ears, but the ears are quite tiny. But anyway, in this case you can see that in cycle zero there were actually fewer than one ear per plant, and after 20 cycles of selection, there were about one and a half ears per plant. But then you look and see what really is going on here. You actually look at these plants, and these plants with this kind of expression are planted when they have no competition, and you're getting all of these ears. And this is very unlike a wild type or a normal corn plant. And I don't know how well you can see this, but this is the normal corn plant, the one that started cycle zero. And you can see that there are two ears potential there. One there and one there. But this one actually is probably the only one that's going to develop. And after 23 cycles, we've created a plant that is totally unlike anything. There were no plants in cycle zero that looked like that. After 23 cycles of selection, we all a sudden have something that's completely novel. Now, in fact, I will back up, and it's no completely novel because we have a single gene mutation that causes something that looks like that. It's called the teosinte branch gene, which John Doebley here in the genetics department is studying. But this is not a single gene. This is the cumulation of many genes giving this expression. And one can imagine, I hope you can imagine, that if we created an environment where that was the selected type, we could actually create almost what looked like and maybe eventually a whole new species. This is some of my own work. I've had a number of my students work on this. This is the chart I was showing you earlier. This is called vegetative phase change, and some of you may be interested in this for a different reason. All plants go through what we call vegetative phase change. This is not going from vegetative to reproductive. This is going from what we call juvenile vegetative structures, which are generally simpler. They, in the case of corn, are shorter and narrower. They have this blueish epicuticular wax. Epicuticular means above the cuticle. They have a blueish appearance because of the epicuticular wax, and they are simple trichomes so they have no hairs and they have no bulliform cells. And bulliform cells are the cells that allow the corn leaf to roll up in a drought. So these plants don't have, the juvenile don't have that. Then we have the transition zone leaves, which are a mix of the two different traits, and the adult leaves, which are glossy green, and they're more complex. They have trichomes and hairs and bulliform cells. They have a glossy appearance. They're bigger and wider. They also are better at photosynthesis. So the plant goes from this stage, the juvenile stage, to the adult stage. All plants do this. Many plant people don't recognize this. The one that all of you may have seen or at least maybe can imagine is how many of you have seen the eucalyptus that you often seen in floral displays with the round kind of silvery leaves? That's the juvenile phase. If you go to California and see those enormous eucalyptus trees, the juvenile phase is one with those little round leaves. The big sword shaped leaves are the adult leaves. So eucalyptus is the extreme, but all plants do this. So what we did, and we can go into the reasons for this, is we decided to select for differential timing of phase change, what we call phase. So we're going to select in the early direction to make the phase earlier or the change earlier, or we're going to select in the later direction to make it later. This is what we call a transition leaf. I hope you can see here this gray-blue color. And then here is the adult. So this is juvenile tissue and adult tissue. And then here is a cartoon of the same thing. This is the stippled area is the adult and then the white area here is the juvenile. So this would be the transition leaf. An early transition leaf, a mid transition leaf, and then a late transition leaf. So what we selected for in this study, the only thing we selected for, was the last leaf with juvenile wax, and this would have been what they looked like. So we would grow thousands of plants, we would go out and look for the ones that had the latest transition, and that would be our selection. I just want to, since Cassie mentioned that I have taught corn in the classroom and teacher ed, one of the great moments you have in a classroom is that I was talking about this and teachers were handling the plants and one of them said, oh, this is a transition leaf, and I was like, well, how do you know that? And they were feeling them. And because this part of the leaf has hairs, it's rough, and this part of the leaf has no hairs, it's smooth. And that's one of the moments as a teacher you go, yes, this is fabulous.

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So here's the direct effect of selection. Really powerful. Really precise. These are what we call linear regressions. The R square is perfect. Linear regression is 1.0. You can see these are about as close as they possibly could be. We can control this trait. We can really move it very easily. We've done 11 sections in this slide. We've actually done many more since then. Now, this is what we would call an indirect effect. This is the number of transition leaves. We only selected for the leaf with wax, so the transition leaves are doing what they want to do, if you will. And you can see here that they are really following along. So this could a pleiotropic effect. This could be the same genes affecting this trait. That would be my guess because they're very similar. Now, this is, we're getting linear changes here, but they have nothing to do with the changes that we see with phase change. So this would be what we might call genetic drift. The genes are just doing something else. I would actually guess that our selection technique is resulting in some inbreeding, and we're actually narrowing the germplasm base and we're getting smaller ears because of inbreeding. This would be an indirect effect, but it would not be related to selection. So these are the kind of relationships we can see. Again, this might be hard to see, but the early direction, if you can see this, the upper leaves here, all of the leaves are more narrow. Here's the early cycles. The leaves are wider. It's hard to see in this light, for me anyway, the color difference. This plant would be much bluer. This would be glossy green. And there are fewer what we call tillers, basil branches. That's another indirect effect. Much like Natalia de Leon's corn teosinte branch experiment, one of the other things we're seeing in this experiment is we're seeing our selection, which clearly involves many, many genes because of the way the population is changing, actually is mimicking single gene mutations. So this is a single gene mutation called corn grass, and this is the cycle 11 late which we selected for. I was talking to my colleague, Natalia, and I said I don't know how much longer I want to do this experiment because we pretty showed, and she said, oh you're going to keep doing it. And I was, why? Well, I thought why. And it's because we want to see how crazy we can push our plants. Like I showed you, Natalia's plant that was unlike most normal corn plants, and last summer, so I was having this conversation over the last winter, last summer I started to see phenotypes in I think what is now cycle 15 that are completely non-normal corn plants. So this is, again, this is the power of selection, and this is the power that actually results in the diversity in the world around us. So here's a group of cycle, let's see, where am I? There we go. A group of cycle 11 late. You can see they're all more narrow. They have more tillers. I can imagine in this light that these are bluer. These are, you can see a little bit more glossy, wider leaves. Here's a cycle 11 leaf eight ear from cycle 11 early. So it's wider. It's more adult. The leaf eight in cycle 11 late is more narrow. And, again, if it wasn't for the light, I hope you can see that this is a dull bluish-gray. This is a brighter glossy green. But I'm sure you can see these striations, these lines here. Those lines are thrips damage. The late, getting backwards here, the juvenile tissue in which that leaf eight is a juvenile tissue is more susceptible to thrips. By making this population on the left transition earlier, we get less thrips damage. This is totally a indirect effect. I think it is probably a pleiotropic effect. I think the wax on the early cycle on the left is probably more resistant or offers resistance to thrips that the wax on the leaf on the right does not. So earlier I mentioned a pleiotropic effect. This would be a physiological effect. I might have just said this is pleiotropic. This would be a physiological relationship. And then another relationship that we see is slow phase change where we have more juvenile tissue. We get more rust susceptibility, and in the early direction. And again, you can see these leaves are wider and glossy green. We get less rust resistance. So by selection simply for that trait of waxed phase change or timing, we actually affect the disease resistance. Example three. Selection for altered carbohydrate synthesis in sugary-1 endosperm. Sugary-1 is the old fashioned type of sweet corn. It's the one that happened before the super sweets. We've had sugary-1 sweet corn in the northeastern United States for at least 200 or 300 years. Maybe some of you even remember names like Golden Jubilee. That was sugary-1 type corn. And this is selection for altered carbohydrate synthesis in sugary-1 corn. So carbohydrate synthesis is a complex operation. And if you think about it, it's a very important operation because our civilization depends on carbohydrate. 60% of our food supply directly depends on corn, wheat, and rice, and what we eat is the starch that those crops produce. So this is a very important reaction, but it's also very complex. Starch synthases, they result in branching and debranching enzymes. I'm sorry, these are the enzymes that are needed to amylopectin, which is the main form of starch. Starch synthases, branching enzymes, and debranching enzymes. So here are the starch synthases. They make the chains longer. So here is where we start, and then we have longer chains. Then we have branching enzymes. And you see that the branching enzymes put more branches on these. And then, and this is where if you need an example of unintelligent design, an intelligent designer would never do this. Because apparently the branching enzymes are too efficient, we need debranching enzymes to clip off some of the work of the branching enzymes. It seems very inefficient and unintelligent to me. So we have the debranching enzymes and then once the debranching enzymes have done their work, this structure crystallizes and forms a starch granule. And that starch granule is largely made up of amylopectin. So isoamylase is the product, is the enzyme that is made by the sugary-1 gene. Here's the sugary-1 gene. Isoamylase-1 is a debranching enzyme. So isoamylase-1 function as starch debranching. We knock isoamylase-1 out, and instead of amylopectin we get this highly branched molecule called phytoglycogen. And phytoglycogen is really important because it's what makes the old fashioned kinds of sweet corn creamy. It gives you that creamy feel in your mouth. If you eat field corn, which has the amylopectin, you get gritty, starchy feel in your mouth. If you eat sweet corn, you get this creamy, very favorable type of mouth feel. So, the biochemical hypothesis, I learned this after I started this experiment, the biochemical hypothesis was if you have a mutation of the sugary-1 gene, you don't have isoamylase-1, and therefore you cannot make starch. And this is a dry ear of a sugary sweet corn type. So this homozygous sugary-1, no isoamylase is being made, no amylopectin is being made, and you get this glassy wrinkled appearance. Well, fortunately or unfortunately, I'm not a biochemist. I didn't know about the hypothesis. So I blundered ahead with plant breeding. So this was cycle zero. This was the initial population I started with. And I just wanted to see whether visually I could actually change this population. All I did was visually select for the ones that looked more starchy. And after seven cycles of selection, I have ears that everyone, except, even me, but if I showed this to a field corn breeder, they would say, oh, that's wild type starchy corn, it doesn't have any mutations. And over on the other side you can see cycle seven in the sugary direction. The kernels are more wrinkled, but they don't look too different from cycle zero. So after seven cycles I actually showed that the biochemical hypothesis was wrong, which was not my intention because I didn't even know it existed. But I showed that we could change this, which must mean, and a number of my grad students are now working on this, it must mean that we changed enzymes in this pathway to actually make starch through a different loop or a different way. A good friend of mine now, Martha James, when I first told her about this, well, a number of years after I first told her about this, she said, you know, the first time you told me about that I was crestfallen because I didn't believe it was possible. Because this was her theory that it wouldn't work, and simply by selection we changed it. So here are the changes that we see. We don't see big changes in total carbohydrates. The red line is the extreme sugary population. The black line is what we call pseudo starchy type. And you can see there's not much difference here. There's no significance. Total sugars hasn't changed at all. Nothing's changing there. Ah, but starch has changed dramatically. Indeed, despite the biochemical hypothesis, the pseudo starchy direction is making significantly more starch than cycle zero made. Oh, I'm sorry. So these are both from the pseudo starchy direction. So this is pseudo starchy. Starch is being made, and this is phytoglycogen. This is the thing that makes sweet corn creamy. And you can see it's dropping off to nothing. This is about the level that field corn, commercial corn that we feed to cows and pigs, makes of phytoglycogen. So simply by visually selecting, just looking at the ears, we're able to make this kind of change. Kernel weight. You might imagine, if you remember those starchy kernels I showed you, kernel weight changed. In the sugary direction it went down, and in the starchy direction it went up. You'll notice it really just plateaued. Well, in this direction it plateaued at cycle one. This one it really dropped after cycle one. But we made changes in weight. All right, so we made big changes in weight, but we have no change in overall yield if we measure the plants. What's going on? What's going on is the plant is compensating. And this is clearly an example of possibly two things. What's happened here is in the starchy direction where the kernels are heavier, here, the kernels are heavier, there are actually fewer kernels. You can see there's fewer rows per ear, and you can see that the ears are smaller. So the plant is compensating for my selection. I'm forcing the plant to do something that most likely the plant doesn't want to do. Sorry for being anthropomorphic. And the plant is compensating. So the plant only has so much photosynthate or carbohydrate, and in this direction, it makes smaller ears. In this direction, it makes bigger ears. Well, this could be two things. This could be a physiological effect where the plant is actually changing other genes to compensate for the heavier kernels, or it could be a linkage effect. We now know that there's a linked gene for row count close to, well it's not real close, but close to one of the starch synthesis genes that we've changed. So this could be either linkage or pleiotropism. All right, so I'm getting a little short, but I think I'm going to be fine on time. So practical implications. The commercial breeding cycle as a recurrent selection program. Plant breeders have been breeding corn for a long time, and they basically recycle their material. Corn breeding is often held up as one of that major effects or triumphs of science in the last century. The USDA was incorporated in 1862, and after the war ended they actually started taking data on crop yields, and crop yields did not change in corn from 1866 to the mid-1930s. And then in the mid-1930s, they skyrocketed, and this curve has not stopped. This is 2004. We're about here now, about 160. So it keeps going up. So we have really changed corn yields. And in the breeding sense, this could be considered another recurrent selection program. There's a lot of interesting things to say about this curve, but given the interest of time and the point I want to make, I'm going to stick to the breeding part. Selection, and this is kind of my point of the whole talk, is very different from the engineering paradigm. Engineers have schematics, they know how everything works, how everything fits together, and they say, well, let's change this and we know what that will do in terms of the output over here. This, by the way, I thought was pretty cool. I just found it today. This is actually a Fender guitar schematic. One of Fender's electric guitars. I didn't know electric guitars were that complex. So, in 1930, as opposed to the plant breeders that started in 1930, the plant breeders, all they was select for yield. That's all they did. They didn't have any plan about changing genes. They had no way of knowing anything about genes. All they could do was select for yield, and you can see they were incredibly efficient. But if you were an engineer in 1930 and you wanted to engineer corn for high yields, what trait would you change? The Kelvin cycle over there is part of the photosynthetic process that produces sugars. So would you change photosynthetic efficiency? There's been a ton of work done on photosynthetic efficiency. Yield capacity? That means would you breed for plants that actually could produce more yield per plant? Heterosis, hybrid vigor? Plant breeders love to talk about heterosis. How about plant size? Harvest index. That's the amount of yield, grain in this case, versus the amount of total plant produced. Harvest index is actually the green revolution gene. One of the big things that Norman Borlaug did and other green revolution folks is they actually used a dwarf gene to make the plants shorter, but that did not change the yield per plant so that changed the harvest index. Anthesis silk interval, that means how close does the silks come out in corn compared to when the pollen is shed. Ear and kernel size, bigger kernels, would that give us bigger yields? Leaf number, tassel size, leaf angle. So if we were one of those game shows, you could all put your number in and see what you're going to guess, and you'd all be wrong. None of those important physiological traits have anything to do with yield, or at least have anything to do with the changes that we've seen over a hundred years. Anthesis silk interval, which we know to be related to tolerance, especially drought tolerance, did change. But the things that were most related were things that maybe are surprising. Tassel size, this is plant from the famous CALS artist John Steuart Curry. He painted this painting in the 1930s, and here is what a tassel of field corn looked like in the 1930s. This little wisp here is the tassel of field corn today. The other thing that happened was leaf angles. Leaves here are horizontal; here they're very upright. This is probably related to the fact that today we grow corn at the level of about 30,000 or 40,000 plants per acre; here we were growing them about 15,000 plants per acre. So this is probably, and again I say probably because we don't really know, probably related to crowding and stress tolerance. I also like to think that these big tassels also threw a lot of shadow on the plant, and that may be as well. But we actually don't know that. Heterosis, which is one of our favorite targets for getting competitive grants, not so much. And I love Duvick's quote here. Duvick, a long-time worker at Pioneer Hi-Bred, did this work, and he said, "The maize plant has made several decisions on its own when subjected to plant intense selection." We didn't make these decisions; the plant made the decisions. So commercial breeding as recurrent selection. Harvestable yield increased dramatically. That's the direct effect. Selection in harvestable yield resulted in changes in morphology and physiology and genetic background that we had no idea would happen. And here's the big tassel and the little, tiny tassels. As a matter of fact, today corn breeders in companies like Pioneer are made to make sure they select for bigger tassels because they're getting so small that they're actually problematic. These changes were not planned or predicted but changed in response to selection for harvestable yield. And what I'm trying to get across here is selection for phenotype is a very powerful tool. The last five minutes I have I'm going to talk about breeding sweet corn, or at least one of my current projects that I'm really excited about. This is breeding wow sweet corn. I usually don't like cutesy names, but literally every person who has ever bitten one of these ears, the first thing they say is wow. Even if I tell you you're going to say that and you say no I'm not going to say that, you say it. And this is a whole new type of corn. And, actually, what I'm going to talk about is kind of a hybrid between the engineering paradigm and the breeding paradigm. So there are a number of important genes. There's the sugary-1 gene that we know from archeological records has latest at least 2,000 years. The sugary-1 gene is poorly named. It doesn't make sweet corn sweeter. It makes it creamier. The supersweet gene, which was discovered by John Laughnan who was born in Baraboo, Wisconsin, and he was at the University of Illinois when he did this, actually does make it a lot sweeter. It makes it maybe about 35% sugar, but no phytoglycogen. So the supersweets don't actually have a nice texture. I'm going to skip for the sake of time the next two bullets. Sugary enhancer is a very common one we see in Wisconsin. This was found by a man named Dusty Rhodes, also at the University of Illinois. What I want to concentrate on here though is the shrunken-2 intermediate gene, which was patented by my good friend Curt Hannah at the University of Florida. We could talk a long time about patents, but that's a whole other story. And then I developed a new type of corn called the sugary-1 shrunken-2I corn which combines shrunken-2 intermediate with the sugary gene. And this is the wow corn, and it really offers something very different. So here's the shrunken-2I. It's actually pretty starchy. It's not good eating. Here's shrunken-2I with sugary genes segregating. That's a classic Mendelian segregation there. 75% of these are not sugary-1, and then you can see the sugary-1 genes. This is a homozygous sugary-1 gene, shrunken-2R which is the reference of the supersweet type of corn, and shrunken-2R segregating sugary-1. I'm not sure that last one is right, but we'll worry about that later. This is the schematic. This is how plants make starch. A very complex pathway. The two big places I want to draw your attention to are here. This is the AGPase, adenosine, I'm actually on TV so I'm not going to try to say it. It's an enzyme that converts AGP glucose, and we get this product. And then down here, so this is the shrunken-2 or supersweet gene, and then the sugary gene is this one here, iso-1. So we can either knock this one out or knock this one out. Rushing a little bit because of time. The shrunken-2I and shrunken-2R are the same genetic locus but two different alleles. Shrunken-2R completely knocks out any starch synthesis. Shrunken-2I makes some starch. But they're at the same locus. So, simplified schematic. We start off with glucose, we get a hexose phosphate. Shrunken-2 converts that hexose phosphate. This the gene. It makes an enzyme that converts hexose phosphate to ADP glucose, and sugary-1 then is involved in converting ADP glucose to starch. That's the normal pathway. We knock out the sugary-1 enzyme. We knock out sugary-1, we knock out isoamylase-1, the enzyme here, we get instead water soluble polysaccharide. That's the same thing as phytoglycogen. That's that creamy texture. Very nice. People really like that. We knock out the shrunken-2R gene, and that knocks out ADP glucose pyrophosphorylase, and sugars accumulate with no starch. It's got great sweetness, but a lot of people complain about the texture. A lot of people say it's too sweet. My invention, if you will, is to combine these two, and we have the shrunken-2I gene. So it makes a little bit, notice the X is a little bit smaller, it makes a little bit of this enzyme, so it makes a little bit of the ADP glucose, and then the sugary-1 gene knocks out amylopectin synthesis and you get WSP. Sorry. So you get the WSP. So in this case, you get not as much sugar as here. You get less sugar, but you get the nice creamy mouth feel. And this is the data from that. I won't pay any attention to the first column, which is total carbohydrates. Let's look at phytoglycogen. This is the creaminess factor. Here's the sugary corn, the old fashioned corn. About 26% phytoglycogen. The supersweet has almost no phytoglycogen, only about 6%. The shrunken-2I, that was that starchy one that was on the left of the picture, makes just a little bit. But the double mutant, which is the one that I developed, makes about half of what the sugary makes. So it's enough to get this creamy feel. Total sugar, the old fashioned sugary corns were not actually very sweet. Only about 8% sweetness. The supersweets, in this example about 12%. And then the shrunken-2I is actually less sweet than the sugary type. But then this one, actually the double mutant, the wow corn, is actually sweeter than supersweet, but it doesn't taste sweeter because sweetness is always a mixture of taste and flavors. Because you're getting this nice phytoglycogen, you're getting a whole different mouth feel which makes that sweetness very flavorful. And I actually think the wow corn is actually better used as a fresh vegetable uncooked. I think it could be the equivalent of the banana. You just take it home. You strip off the husks. You eat it. It's delicious. No cooking necessary. Unfortunately, my good friend Curt Hannah patented it, so we're dealing with IP issues. But eventually the lawyers will figure all that out. So, actually, I'm pretty close to on time. This is my team from this past summer. Fabulous graduate students and undergrads. The people who helped me with this talk. A number of past graduate students who are not in this picture. Bruce Abedon's not here, Mike Chandler, Meg Hurkman, Federico Basso, -- and Eric --, they all worked on parts of this. Hallie Dodson did the wild corn stuff, and then Brittany Glaza and Brian DeVries did some of the more recent work. Brian DeVries, Brittany, Tessa, Matt Murray, Ashley, these are the grad students. Adrian and Reed. I think there's one missing there. And Herman is in the back there. And then he always, this is one of those kind of Where's Waldo kind of, my research program manager is probably the most important person, Pat Flannery, is always in the picture but always never seen.

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Maybe you can see an extra pair of legs down here or something That's Pat. And then we've got support from all sorts of agencies. And I will leave you with one of the great American philosopher's quotes. And I would be happy to take any questions. Was I supposed to say something? Thank you all for coming.

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