Will GMOs Bring Back The American Chestnut Tree?

In the early 20th century, a blight fungus wiped out most of the 4 billion American chestnut trees on the eastern seaboard. The loss was ecologically devastating. Short Wave host Emily Kwong https://www.npr.org/people/767284140/emily-kwong dives deep into how scientists are trying to resurrect the American chestnut tree — and recent controversy over a plan to plant genetically modified chestnuts in the wild. Want to hear about more efforts to recover endangered or lost species? Let us know by emailing [email protected] mailto:[email protected]! See pcm.adswizz.com https://pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences. NPR Privacy Policy https://www.npr.org/about-npr/179878450/privacy-policy

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• 0:00Speaker 00

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• 0:16Speaker 01

  Hey, short waivers. Emily Kwong here with an episode from our holiday archives all about chestnut trees. Stick around until the end of the episode for an update on the latest science, too. You're listening to Short Wave from NPR.

• 0:33Speaker 01

  Hey, everybody. Maddie Sofia here with Short Wave reporter Emily Kwong.

• 0:36Emily Kwong?

  Hey, Maddie.

• 0:36Speaker 01

  Hey, Kwong. You've been delving into the mystery of what happened to one of the most significant trees in the United States, the American chestnut.

• 0:44Emily Kwong?

  Yes, the Kwong family is very into chestnuts.

• 0:49Emily Kwong?

  Every Christmas season, we buy them roasted on the streets of New York. My dad folds them into his stuffing. And of course, you honestly can't go anywhere this time of year without hearing Nat King Cole sing about them. You know what I'm talking about.

• 1:01Speaker 01

  I do.

• 1:06Emily Kwong?

  It just sets the mood.

• 1:08Speaker 01

  Right.

• 1:08Emily Kwong?

  You know what time it is. But Maddie, it took years of eating chestnuts, listening to this song, to ask myself, why haven't I ever seen a chestnut tree in the United States? Have you ever wondered that?

• 1:21Speaker 01

  Oh, every day, Kwong.

• 1:23Emily Kwong?

  No, really? Have you ever wondered that?

• 1:24Speaker 01

  No, I haven't.

• 1:26Emily Kwong?

  It's odd, because by 1945, when that Christmas song was written, most of the 4 billion chestnut trees on the eastern seaboard had died. The chestnuts you buy these days, the ones I eat, are all imported from Europe and Asia.

• 1:41Speaker 01

  Huh.

• 1:42Emily Kwong?

  And if you ask people from Appalachia, where the chestnut was an important species for the ecosystem and the economy, this tree represented a way of life that was lost. Rex, man of Kentucky, says his father never got over it.

• 1:54Speaker 03

  He never became reconciled to that loss. He was always hopeful that something would happen, you know, that the tree would come back.

• 2:06Emily Kwong?

  Now, Rex is one of the many people working to bring a version of the American chestnut tree back and tapping into the very genetics of the tree to do it.

• 2:15Speaker 01

  Today on the show, the death-

• 2:17Emily Kwong?

  And potential rebirth-

• 2:18Speaker 01

  Of the American chestnut tree. How science is trying to give this functionally extinct tree a fresh start.

• 2:24Emily Kwong?

  And how that has created some controversy.

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• 3:52Speaker 01

  OK, Kwong, the mysterious disappearance of the American chestnut tree. Take it away.

• 3:57Emily Kwong?

  All right, let's bring it back to Rex Mann. He's retired from the US Forest Service and really knows the trees of southern Appalachia. Last year, he gave a TEDx talk that opened with this memory of sitting around the fire as his father, Howard Mann, told chestnut stories.

• 4:12Speaker 05

  He's talking with great passion about what the tree meant to his people. Its huge size, the wonderful wood used for everything, and the never-failing crops of chestnuts that nurtured the mountain people.

• 4:28Emily Kwong?

  It's a beloved tree, and historical accounts back this up. Chestnut trees were abundant, an estimated 20% of the Appalachian forest. They could grow over 100 feet tall, and their chestnuts coated the ground. So wildlife species from whitetail deer to black bears, wild turkeys, and squirrels depended on them. Farmers could lean on chestnuts as feed for their hogs, and the nuts were so valuable that residents in the Smoky Mountains gathered bushels for trading purposes.

• 4:53Speaker 03

  Take them to the local country store, and they would swap them for... Things that they had no money to buy, like shoes for the kids.

• 5:03Emily Kwong?

  But Rex, he never saw any of this because in 1904, a mysterious and deadly fungus was discovered on trees in New York City. It likely came from a nursery stock of Japanese chestnut trees, and this blight began to spread down the coast. So by 1950, a few decades later, most of the 4 billion chestnut trees were dead or infected with blight fungus.

• 5:23Speaker 01

  Okay, so what does this fungus look like?

• 5:26Emily Kwong?

  Okay, it's a parasitic fungus with a bright yellow-orange color. It can grow underneath the bark, looking like these orange gashes, or on the top, creating these actively fruiting pustules.

• 5:36Speaker 01

  Pustules are never good.

• 5:37Emily Kwong?

  Yeah, it's pretty gross. And, and pretty sad because, once infected, the trees really don't stand a chance. The blight, it cuts off nutrients and water to the rest of the tree. And for America's forests to change so dramatically, just when the Great Depression hit and people really relied on these chestnuts, it was devastating. Rex remembers as a kid walking through the aftermath.

• 5:56Speaker 03

  What I saw when I was growing up was what I would call the gray ghosts, the trunks of the chestnut. They were still standing in the forest.

• 6:10Emily Kwong?

  Important footnote, the blight doesn't actually kill the root system of these trees. American chestnut trees, Jared estimates there are about 400 million now, are basically shrubs sprouting from the roots. And they get infected by the blight and are killed back before reaching sexual maturity. It's like the whole species has been condemned to eternal infancy.

• 6:29Speaker 01

  Poor little trees never get to grow up.

• 6:31Emily Kwong?

  Exactly. Because the blight lives on, naturalized in the environment, in the leaf litter, on other trees that don't get sick from it. So that's why, by 1950, the American chestnut tree was declared functionally extinct.

• 6:44Speaker 01

  Right. So the big, strong trees, they were basically gone?

• 6:46Emily Kwong?

  Yes. And Rex remembers a researcher lecturing to his forestry class, basically saying, "They're gone."

• 6:53Speaker 03

  I remember him saying, "Hey, the tree's gone forever. Forget about it." And they're just giving up all hope.

• 7:01Emily Kwong?

  But Matty, there might be hope.

• 7:03Speaker 01

  Chestnut tree hope.

• 7:05Emily Kwong?

  Something like it. So in 1983, a group formed the American Chestnut Foundation. Rex Mann has been a longtime member of the Kentucky chapter. And as the science has evolved, so too has the foundation's strategies for bringing back a version of the American chestnut tree that can fend off the fungus.

• 7:21Speaker 01

  So it can grow and essentially reproduce on its own in nature.

• 7:25Emily Kwong?

  Yes. And I cannot overstate, Maddie, how far reaching this effort has been. There are 16 state chapters, and at one point, this man named Bill Owens recorded a song to help them raise money.

• 7:36Speaker 01

  Like manhood from heaven. Oh, wow. Yeah, he did.

• 7:41Emily Kwong?

  Sung alongside his very famous niece.

• 7:48Speaker 01

  Dolly!

• 7:49Emily Kwong?

  The one and only.

• 7:50Speaker 01

  Is this real?

• 7:51Emily Kwong?

  That's Dolly Parton.

• 7:54Emily Kwong?

  And she released this song a few years ago for this whole effort. The song ends with the line, "Oh, mighty magic chestnut tree, thank God for second chances." And it's science that's giving this tree a second chance.

• 8:08Speaker 05

  My name is Jared Westbrook. I work for the American Chestnut Foundation.

• 8:12Emily Kwong?

  Jared is the director of science there overseeing this three-pronged initiative to restore the tree.

• 8:17Speaker 01

  Tree-pronged approach, if you will.

• 8:19Emily Kwong?

  Wow. Wow.

• 8:21Speaker 01

  Break it down for me, Kwong.

• 8:22Emily Kwong?

  All right. Strategy number one, prong number one, is traditional breeding. So for nearly a century, scientists have been experimenting with crossbreeding the American chestnut with the Chinese chestnut tree, which does not get sick from the blight.

• 8:34Speaker 01

  Okay, so it's like a combo tree.

• 8:36Emily Kwong?

  Right. And over the decades, they've taken these offspring and performed a special kind of crossbreeding called backcrossing that reinforces the traits of the American chestnut tree. And it's been pretty successful. There's three generations of these hybrids at the foundation's research farm in Virginia.

• 8:52Speaker 05

  So we've planted hundreds of thousands of trees at this farm, and now we're selecting the 1% most resistant trees.

• 9:00Emily Kwong?

  It's still slow going and maybe not the best strategy because Jared's realized that blight resistance is not a simply inherited trait after all.

• 9:08Speaker 05

  So there's a lot more genes involved, and as you do more crossing.

• 9:13Emily Kwong?

  To American chestnut, you get trees that are less blight tolerant. So traditional breeding has its limits. The more you make these trees American chestnut-y, the less able they are, it appears, to combat the blight. Which brings us to prong number two, attacking the blight itself by infecting it with a virus.

• 9:29Speaker 01

  That's probably fine. I'm not worried about that at all.

• 9:31Emily Kwong?

  But it's kind of, it makes sense, right, to go directly to the source? Counter-Strike? No?

• 9:36Speaker 01

  Sure. What happened?

• 9:38Emily Kwong?

  Well, this strategy has been effective in Europe, saving their trees from blight. But the problem in the US is you'd have to go around and individually infect each spot of fungus on the tree, and that is just-

• 9:49Speaker 01

  Not realistic.

• 9:50Emily Kwong?

  So much work. But we can't go out to the forest and treat 400 million trees with this virus every year.

• 9:58Speaker 01

  So it's too labor-intensive for a large-scale restoration, but it works for our breeding efforts.

• 10:06Emily Kwong?

  So what about prong number three? What's that? Prong number three, it's the most interesting, but also the most controversial for some folks because it involves transgenic organisms. So think about corn or cotton.

• 10:18Speaker 01

  Got it.

• 10:19Emily Kwong?

  Okay, we've added new genes to those agricultural crops to protect them from insects or allow them to tolerate certain weed killers.

• 10:27Speaker 01

  Yeah, sure, we got some GMOs out there.

• 10:29Emily Kwong?

  Yeah, and members of the New York chapter wondered, could we do something like that for the American chestnut tree? Researchers at the State University of New York, their College of Environmental Science and Forestry, tackled that question. They chose a gene naturally found in wheat and a lot of other grass plants and inserted it into American chestnut trees. They planted that first transgenic tree outside the lab in 2006, and their hope is that such a tree will be planted in the wild someday.

• 10:56Speaker 01

  And how does this gene affect the American chestnut tree?

• 10:59Emily Kwong?

  Okay, so this gene is responsible for creating an enzyme which has the ability to combat oxalic acid. And oxalic acid is what's ultimately attacking trees that have been infected with the blight fungus, killing their cells. So this gene is essentially protecting the tree from being totally consumed by the fungus.

• 11:17Speaker 01

  Right, so these trees have been genetically modified at this point?

• 11:20Emily Kwong?

  That's right. They're not wild American chestnut trees, but a GMO version. Researchers at SUNY call these samples darling American chestnut trees. And before they can be planted in the wild, they have to pass federal regulatory approval. The USDA, the EPA, the FDA, they all have to sign off.

• 11:39Speaker 01

  And what are these regulatory agencies looking for?

• 11:41Emily Kwong?

  Basically, they'll want to know how these transgenic chestnuts are impacting the environment around them. The soil, nearby fungi, other plants. They'll want to know about tree growth rates and pollen flow. There are a lot of variables to consider, a lot of testing to be done on trees that are still pretty young, and that's made some people very nervous.

• 12:02Speaker 01

  Right. Some people are worried about genetically engineered trees and other things being released into the wild.

• 12:08Emily Kwong?

  Yes. For those concerned about GMOs, this tree is raising eyebrows. In March, two members of the Foundation's Massachusetts Rhode Island chapter stepped down over this. A group of activists released a white paper saying this would be a, quote, "massive and irreversible experiment." They're fearful this could change the ecosystem in ways we just can't predict. And Jared gets where these critics are coming from.

• 12:28Speaker 05

  It messes with people's idea of what is natural or what is nature. And we're doing an interventionist approach to a problem that humans caused in terms of bringing in, introduced pathogens that the native species are naive to and they're susceptible to.

• 12:49Emily Kwong?

  Basically, human intervention caused the blight, so human intervention should fix it. But of course, if this happens with the chestnut tree, it could open the door for genetically engineering other trees, forest biotechnology. And there's public opposition to that idea.

• 13:01Speaker 01

  Big questions out there, Kwong.

• 13:03Emily Kwong?

  Yeah, this tree, honestly, is the poster child for raising those questions. What lengths are we willing to go to to bring back trees? Jared argues that because the American chestnut tree was such a keystone species in its heyday, so ecologically important, that this tree is worth all the trouble.

• 13:21Speaker 05

  It would be very difficult to try to resurrect all of the species that have gone extinct as a result of human intervention. But if we were selective about choosing keystone species that have a large ecological effect, I think that is where the intervention is justified.

• 13:39Emily Kwong?

  And the public can weigh in on these decisions regarding these transgenic chestnut trees when they're up for federal review next year.

• 13:48Speaker 01

  All right, Emily Kwong, I appreciate you. Thank you for sharing with us the scientific saga of the American chestnut tree.

• 13:53Emily Kwong?

  Such a saga.

• 13:54Speaker 01

  Yeah.

• 13:54Emily Kwong?

  You're welcome, Maddie.

• 14:01Emily Kwong?

  Since this episode first published five years ago, a lot has happened. In December 2023, the American Chestnut Foundation withdrew its support for SUNY's Darling Transgenic Chestnut Project. I got in touch with Jared Westbrook again to explain why, and he said the foundation found issues with the transgenic trees in the long term, including diminished blight resistance and slow growth. So I reached out to SUNY for comment. Andrew Newhouse, who directs the Chestnut Restoration Project there, told me over email that the college has made improvements to their programs since these concerns came to light, and he defended the viability of darling trees against blight in the long term. He wrote, "No single tool or approach will

• 14:44Emily Kwong?

  fully solve the problem of chestnut blight, but we believe that biotechnological approaches, including the use of transgenic trees, can be a safe and effective part of the solution." As for the American Chestnut Foundation, Jared says, this is over email, too, that their main strategy at the moment is an advanced version of Prong 1, where the foundation uses genomics to select the very best hybrid trees, crossbreed them, and ultimately create a line of progeny with blight resistance woven into their DNA at birth.

• 15:21Emily Kwong?

  That's all for me, Emily Kwong. Thanks for listening to Short Wave, the science podcast from NPR.

• 15:51Speaker 00

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