Hacking Trees To Bring Back The American Chestnut

A researcher in a safety harness pollinates an American chestnut tree from a lift. Another researcher is on the other side of the lift and appears to be taking notes. The tree has bags over some of its branches, presumably to control the pollen that gets in. The lift has a grey platform and orange arm.

“Chestnuts Roasting on an Open Fire” is playing on the radio now in the Northern Hemisphere which begs the question, “What happened to the American chestnut?” Would you be surprised to hear there’s a group dedicated to bringing it back from “functional extinction?” [via Inhabitat]

Between logging and the introduction of chestnut blight, the once prevalent American chestnut became increasingly uncommon throughout its traditional range in the Appalachians. While many trees in the southern range were killed by Phytophthora root rot (PRR), the chestnut blight leaves roots intact, so many chestnuts have been surviving by growing back from the roots only to succumb to the blight and be reborn again. Now, scientists are using a combination of techniques to develop blight-resistant trees from this remaining population.

The American Chestnut Foundation recognizes you can’t improve what you can’t measure and uses a combination of “small stem assays (SSAs) performed on potted seedlings, improved phenotype scoring methods for field-grown trees, and the use of genomic prediction models for scoring resistance based on genotype.” This allows them to more rapidly screen varieties for blight resistance to further their efforts. One approach is based on conventional plant breeding techniques and has been crossing blight and PRR-resistant Chinese chestnuts with the American type. PRR resistance has been found to be less genetically complicated, so progress has been faster on resistance to that particular problem.

Research is also ongoing on transgenic solutions to both the blight and PRR. Initial experiments using a wheat gene had mixed results, but researchers hope to develop a version that can be expressed in more nuanced conditions like when a tree is more susceptible to infection. This could prevent or reduce some of the negative affects of the transgenic hack like increased tree mortality and metabolic costs with always producing the oxalate oxidase enzyme that interferes with the blight toxin.

If we’re tinkering with genomes anyway, maybe boosting the American chestnut’s photosynthetic efficiency isn’t out of the question? If you’re more interested in making insulin or combating mosquito-borne diseases, there’s a biohack for that too.

33 thoughts on “Hacking Trees To Bring Back The American Chestnut

  1. As far as I know we’ve got plenty of those things here in the Netherlands, and they are being treated as an invasive spieces. I’ve seen a few and they’re not very big nor impressive. I don’t know whether that is because they’re being culled or whether it’s a different / related spieces. I also don’t know if these are more resistant to the fungus. It would be nice if it could help to create a fungus resistant variant.

        1. Exactly. Silly. We have a very large mulberry tree in our yard that’s not doing well (they’re not a long-lived tree) so I’ve planted two replacements that won’t be huge until I’m long dead, but either way, the wildlife and the humans love those mulberries. The nursery charges $150 for a mulberry sapling, meanwhile they’re considered invasive elsewhere and cut down. Makes utterly no sense.

          1. “meanwhile they’re considered invasive elsewhere”
            I mean, that’s how invasive things work – they’re fine and normal in one place, just not in the place they’re invading.

      1. If it crowds out other desirable crops, or hosts pests that damage desirable crops, without aggressive control grows in undesirable places, or jut grows beyond reasonable harvest, it is a problem.

        1. “Candy from coal”
          It was a thing a few decades ago, but trying to search the web for it this time of year, only seems to turn up the bag of coal Christmas candy.

      2. If it upsets the local ecology by out competing some native and essential link in the food chains without taking their place or something similar then it absolutely should be treated as invasive. And even if it doesn’t if it is getting in the way of the cultivations you actually want…

        There does come a point where you’re better off accepting the damage is done and living with and making use of the changed ecology as long as its stable enough.

    1. The Dutch chestnuts may be what we call here in New Hampshire, Chinese Chestnut. They are a fairly weak tree and don’t grow that large. The wood is fairly soft. I’ve use some of it for wood turning small items but not my favorite.

      1. Dutch here, we mostly have Castanea sativa (edible chestnuts) and Aesculus hippocastanum.

        The first you might know as horse chestnut, the latter as sweet / Spanish chestnut

        (Chinese Chestnut being Castanea mollissima, so not quite the same)

        1. Where I live (WA State, US), we have a chestnut variety that’s referred to as horse chestnut (Aesculus hippocastanum) and the nuts are actually quite toxic, so that’s just confusing the matter even more.

        2. Other way around. C. saliva is the native (and edible) European chestnut, and Aesculus species are horse chestnuts, whose nuts are toxic to varying degrees, but can be made edible by leaching out the toxins. The two species of horse chestnut native to North America are called “buckeyes.”

    2. Most likely Chinese Chestnuts. They are smaller, and carry the blight which hurts American and European Chestnuts. I have a bunch of them but the American Chestnut is supposedly taller

    3. The American Chestnut was a keystone species that was home to woodland creatures and was indeed the tallest tree in eastern US forests. It is an excellent construction material and its demise was an ecological disaster. In short, they were very important and valuable and indeed not invasive.

  2. Here in central West Virginia we still see stumps of pre-blight trees in the forest. They huge and they were very densely distrubuted 35 years ago. Chestnut was a dense and plentiful food crop for stock and wildlife. Chestnut lumber is clear, easy to work, and durable.

  3. My Father, back in 1970 started digging up the sprouts from the roots back in the mountains of southwest Virginia. He planted them in several areas, but he has two giants in his back yard that produces hundreds of chestnuts every year. These are original American chestnut trees, and I have emailed colleges and many other people to no avail. I guess they’re truly not interested. These trees are probably close to 75 foot tall now and very healthy no blight has affected them.

    1. You know oddly, for whatever reason, what I call “academic” growers and researchers of American chestnuts get very exclusive and sometimes downright hostile or dismissive to amateur growers. I have the same experience. I’m growing high-percentage American chestnuts in South Dakota since the blight isn’t very prevalent or never reached the upper Great Plains. A couple years ago the chief arborist at the state’s agricultural college published an article that there are no chestnuts trees growing in South Dakota. I’m not the only one attempting to grow them here so I wrote him an email and he and the ag department ignored me. Hang in there — I’ll bet someday if we ever do find a blight-resistant American, it’ll be an amateur or non academic, non-TACF grower that finds it.

    2. @Greg Johnson said: “My Father, back in 1970 started digging up the sprouts from the roots back in the mountains of southwest Virginia. He planted them in several areas, but he has two giants in his back yard that produces hundreds of chestnuts every year. These are original American chestnut trees, and I have emailed colleges and many other people to no avail. I guess they’re truly not interested. These trees are probably close to 75 foot tall now and very healthy no blight has affected them.”

      “I guess they’re truly not interested.” I cannot believe that. Here are two organizations working hard to bring some form of the (badly missed) Chestnut back to North America. Try contacting them:

      American Chestnut Cooperators’ Foundation (ACCF)

      https://en.wikipedia.org/wiki/American_Chestnut_Cooperators'_Foundation

      https://www.accf-online.org/

      The American Chestnut Foundation (TACF)

      https://en.wikipedia.org/wiki/The_American_Chestnut_Foundation

      https://www.tacf.org/

  4. “Invasive” seems to be a knee-jerk resistance to change. Scotch Broom is considered invasive on Vancouver Island. But it was introduced by expats over a hundred years ago (1850) so is it not native by now? And what species were pushed out upon the arrival of whatever we think is “native”?

  5. I had no idea chestnuts were on the brink, my moms has one in the backyard still growing chestnuts every year. We used to throw the spiked green balls at each other as kids cuz u know, kids are a$$holes. Maybe we would have found more respect for the serds if ee had known they were becoming rare. Im tempted to go and look for some now. I found a sprouted chestnut workin in the garden last year and put it in a pot however it didnt survive the winter.

    1. sounds more like horse chestnuts or sweet gum to me — if they’re green and spiked. the spikes on true chestnuts are brown, very thin, and very sharp and look like fur from a distance

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