Reviving the American forest with the American chestnut | William Powell | TEDxDeExtinction

like to you to first to think about when is the last time you saw an American chestnut tree now you're probably thinking well I haven't seen American chestnut tree and that is actually a sad and true story when some of our most senior people have actually seen American chestnut trees the way they used to be they used to be one of the most abundant trees in the eastern forests so if you were to look at this scene behind me of a patch of the Appalachian Mountains one out of four trees would have been American chestnut in this setting okay quite a few trees now the American chestnut was a keystone species meaning that a lot of other animals and Wildlife relied on it for their survival one of the main reasons why it was a keystone species is because of the mast or the nut crop that it produced year after year it produced a very very stable nut crop the oak trees which has since replaced the chestnut do not produce that consistent stable mast as the chestnut did now you're thinking nuts well maybe that supports things like squirrels well it did supports the corals in fact when we lost the chestnut there's actual school populations in the forest declined okay but a lot of other animals also relied on chestnut and all these that I'm showing here even some animals that are now extinct that you're hearing about in these talks today such as the Carolina parakeet and of course since everybody else has mentioned and I want to mention the passenger pigeon also it probably relied on American chestnut so you think about if you're going to bring back a species such as the passenger pigeon what are you bringing it back to where our force are not the same as they used to be they used to be predominantly chestnut so you might want to first bring back the chestnut before you bring back these other species okay so what I want to try to do it this first part of my talks to convince you that chestnut is a species worthy of restoration and I've just shown you right here how important it is to ecology and it has many other values also the American chestnut was also very valuable as a nut crop for agriculture not only did wildlife like to eat chestnuts but humans like to eat chestnuts also whether you like to eat it roast it or candied or ground it up into a flower where you can make soups or breads or you can even brew it into beer and by the way this is a gluten-free beer for those of you who are like me you can't eat gluten okay so I had a lot of valuing that way it also has very valuable for the wood that had produced the wood was very straight green this was a fast growing tree so woodworkers liked it but one of the key things about it was that it was a very rot resistant wood and so it could be used in outdoors without rotting so what I always tell people is if chestnut was abundant like it was in the past all your decks would be made out chestnut instead that old pressure-treated stuff did this made out now and in fact all telephone poles are probably out of chestnut and you don't have to treat them with all kinds of chemicals okay so it has a very good economic value but in addition to that the American chestnut tree is really part of our history and part of our heritage you probably can't go to a town without finding a chestnut street just like you would find an elm street or maple street you'll always find a chestnut street I particularly like this corner here the intersection of chestnut and Powell for obvious reasons but this is actually in California this is way out of the range of American chestnut yet is still recognized you've probably seen chestnut mixed hitchens and songs such as this a very familiar song at Christmastime and it starts off chestnuts roasting on the open fire you might have learned this poem in school at some point where talks about under the spreading chestnut tree the village smithy stands that is also an American chestnut so it's really kind of part of our natural heritage here in the United States now the American chestnut was one of the largest trees in the Eastern forests before we lost it this is a picture from the force Historical Society showing some Lumberjacks and that's the end of large chestnuts and you can see how large they are this next picture is not actually a photograph it's a painting up and so it's taking a picture of a painting but I kind of like this because it shows a different form of the chestnut if you grow this in the open it actually spreads like that last poem and this one is showing a chestnut harvest and it kind of gave you an idea of how big these trees would get there's a guy up there knocking chestnut down to the people below so these trees got quite large why don't we have chestnuts a day well we don't have them again because of what humans have done we have introduced a exotic pathogen from Asia when people will start importing Asian chestnuts to plant in their yards or in their orchards to have a closeby supply of nuts when we brought that over the fungus that causes chestnut blight moved over with it now this fungus is called cry for nectar parasitic ax and it was very happy to come to United States as you can see here and this is actual real plate of the fungus believe it or not so it came here found a host that was totally susceptible to it and it jumped on to the American chestnut and within 50 years spread through the whole ring to the chestnut from down south and Georgia to up north into Maine okay and it killed somewhere between 3 to 5 billion chestnut trees ok very very damaging now when this was happening people were panicking of course could you imagine driving down the highway and seeing the largest trees on the side of the road all dead at least half of them - a quarter of them we're all just standing up dead this is what people were seeing so they threw a lot of resources at trying to stop the chestnut blight but everything failed and we basically lost the chestnut tree at least the mature large trees just on is still surviving today at the roots so it's not extinct it's just functionally extinct ok so right now there's actually two programs that are having some success at making a blight resistant American chestnut tree they're a breeding program and there's a transgenic program involved with the transgenic program and I'm going to kind of do a quick comparison of the two each of them are viable programs and each of them probably will have some levels of success they each have their own pros and cons though so the brilliant program what they're doing is they're crossing American chestnut to Chinese species of chestnut that are naturally resistant to blight because that's where the blight comes from and then they back cross to American to try to regain all the American traits okay when they do this they end up with a tree that's 1/16 Chinese and of course fifteen sixteenths American which sounds really good and then it is pretty good but I want to do a little illustration for you let's think of the chestnut and chestnut genome as a book okay and let's say that book is filled with words in the words represent the genes in the chestnut okay we know about how many genes are in chestnut and they would fill about a hundred and eighty page book so if you're 1/16 Chinese what that means about eleven pages or close to 3,000 words in that book are from Chinese okay art and Chinese now that might not be important because we have a lot of duplicate gene jeans in the two but it might be important if this is a critical plotline or something like that and the reason why is a potent with Chinese and American chestnut because Chinese just has actually been bred for thousands of years as an orchard tree American chestnut is a wild timber type tree and there's a lot of traits that we don't want from the Chinese chestnut so the problem here is you got to then breed out all those traits you don't want all right that can be done it just takes a lot a lot of work a lot of selection let's look at what you do with transgenics now let's go follow up that book analogy I'm going to take one passage out of that book or one sentence actually a sentence from Thoreau's Walden I kind of like that because he really likes chestnuts and that and when you use that as an example we can put in just a few genes at a time using a natural genetic engineer called agrobacterium tumefaciens this is a bacteria that in a wild moves genes around and plant so what scientists have done is basically tamed this bacteria so it moved genes in that we want to move in so what we're doing is we're only moving two to four genes into the tree so we're not making a big change we're making a very small change to tree and now we don't have to go back and try to get rid of genes that we put in there that we don't really want okay so that's an advantage with transgenics so what do we get these genes from well we can get them from the same place we get the genes for the breeding program we can get them from Chinese chestnut species and we actually are looking at genes from those species some from castaigne Melissa MA some from Cassie Nia so Queenie I but another powerful thing about transgenics is you can move genes actually from other plants I'm gonna give you an example of one of those that have given us some success this summer and that is a gene that comes from wheat and we like this because this is a gene that you normally eat all the time anyway in the gene products so it's generally safe but more importantly is that the way this gene works it detoxifies the asset that the fungus uses its attacked the tree that we know that this fungus the only way you can form a canker and kill a tree is to throw oxalic acid at it if you can remove that you can no longer form a canker all right so what we're basically doing is giving the tree an ability to defend itself against the fungus the tree is not killing the fungus it's only defending itself against the fungus okay now I'm going to show you some of our exciting results from this past summer this is a experiment where we are measuring the size of the tank of growth on some American chestnut trees Chinese chestnut trees and some of our transgenic ones this first line represents the growth on a American chestnut tree the higher that line goes the bigger the canker and eventually will girdle the branch killing everything above it so that's American chestnut very susceptible if you look at Chinese chestnut has a much smaller canker we call it this a superficial canker does not kill the branch all right let's look at our transgenic American chestnut that has the oxide oxidation and what's exciting here is its tracking along with the a chestnut so we definitely shown that we can enhance light resistance using these methods and with this particular gene now we're going to do this again this following this coming summer because you always have to repeat things in science but things are looking very good so let's look at what we have right now we have American chestnut which is very susceptible on your left we have Chinese chestnut which is more resistant on your right this tree that I just showed you called the darling for tree is approaching the level resistance of the American of the Chinese chestnut now what's really exciting is we have some new trees is coming out of our lab right now for the summer and these trees make more of this enzyme that detoxifies the acid okay and what we're finding in our preliminary tests we think these might even be more resistant than the Chinese chestnut and so this is very exciting for us again we have to test them in the field which we will be doing over the next few years okay so what do you do once you have a resistant chestnut tree okay one thing when we make these you only make a few of them so they're not going to be very diverse so we have to try to increase the genetic diversity of these before we put them in a restoration program and we do that by going to the surviving trees in the field and cross them with our transgenic tree and we just developed a new method that allows us to produce pollen from either seedlings or from plantlets in less than a year typically in the field it takes three to seven years to get pollen okay so we have a method now that we can get pollen in one year next year get another group of pollen and we can out cross it until we get a very diverse group of trees we've actually done this we've actually produced nuts from these crosses these nuts have inherited the gene that we put in which is an important point and we also now have nuts that we are sending away to some of our colleagues at Oak Ridge National Lab to check to make sure the nuts aren't any different than the wild-type nuts and that's important also okay so what do we do next from there well to start a restoration program one of the cons of using transgenics is that these things are highly regulated they're regulated by three agencies the USDA the EPA and the da so before we can just release a tree to anybody we have to get their approval but once we get their approval then we can treat it like any other tree and start a restoration program so how do we get in to a restoration program well the range of American chestnut is large there used to be a lot of trees there you don't just go out like Johnny Appleseed and spread them around so what I like to think of is restoration has a start at what I like to call restoration foci these are small areas where you can start established a group of trees and then slowly they'll move out from there this can be on historic sites if you want to try to restore historic site to what it looked like 100 years ago could be on private landowners but what I really like is restoration of mine lands there's a lot of places in the Appalachia where they mined coal then mines are done and they want to return those to the forest these are primary very good places to start restoration using chestnut because there's no trees there to start with we don't want to cut down trees that are already there now where do you go from that point well the next point is really coming gets out of our hands and goes into your hands okay this is where the people through the restoration this is a century-long project so we need you we need you and we need you to help with this okay we need you and your children and your grandchildren to bring these trees back because it's going to take a long time to get back to the over a billion trees in the forest so if you're interested in the helping numerous restoration you can contact the American chestnut foundation I got the website here and they were always looking for help so I want to stop there and give thanks to the many colleagues who helped us get to this point in the research I didn't do this all myself as on the backs of many many researchers like to thank you for coming here and just recognize all the supporters over the years thank you you

Channel: TEDx Talks

Views: 163,225

Rating: 4.9051151 out of 5

Keywords: de-extinction, United States (Country), tedx talks, ted, ted talk, tedx, Revive and Restore, ted talks, William Powell, tedx talk, Revive & Restore, ted x, TEDxDeExtinction, Science, English

Id: WYHQDLCmgyg

Length: 15min 6sec (906 seconds)

Published: Sun Apr 07 2013