Basically they hybridized it with Chinese/Japanese chestnuts (which are blight resistant). Then they take the offspring, test for blight resistance and rebreed those back with purebred American chestnuts. Then they repeat the process. Take those offspring, select for blight resistance, rebreed with American species, etc
After a few generations they created an American chestnut tree that looks almost exactly like the purebred versions but retains the blight resistance of the Japanese and Chinese species
Really amazing work
I'm not criticizing their technique! Nor do I think I know better. This is amazing and valuable work, and I'd love to know more.
https://www.nytimes.com/2020/04/30/magazine/american-chestnu...
Also, it seems rare to find just one gene that encodes a property or compound. Usually you need several genes to form a pathway from a common precursor chemical to your target result. That pathway will be leaky, and it may take resources away from other important chemicals that the plant's lifecycle relies on.
It sounds expensive and time consuming - plants take a long time to compile, and you can forget about reproducible builds. Plus, once you have your GMO, you'll be expected to take care not to release it into the wild, and in today's world, a decent chunk of people will oppose your product because of their personal beliefs.
It could also just be technology. This breeding program has been around for 50 years or so and CRISPR only really took off around 2011. In addition, the original CRISPR-Ca9 caused a lot of unintended changes in DNA and it's really critical that the new trees are morphologically equivalent to the original trees in order for the birds, insects, and animals that depended on them to resume their interactions. Newer technologies like CRISPR-Nickase are much more precise but also very recently developed
CRISPR is... awful in different ways. (It seems to have a lot of trouble controlling how much material it transfers.) It's a laboratory curio or one-off stunt now, but I fully expect it will improve.
It's a tricky business, because chestnut had very particular properties, as wood, that made it quite valuable, and any gene interference, well ... who knows how it will change the resultant wood?
I see what you did there.
I just saw Eliza Greenman speak on this subject, never expected that to circle back to HN.
There is a GMO effort which adds a gene to the American Chestnut so that it produces an enzyme called oxalate oxidase; the gene comes from wheat plants. The enzyme breaks down the oxalate acid produced by the blight fungus. The first GMO tree was planted in 2006 and has held up, as have others in the test plot. IIRC, USDA permission is being sought so it can be planted freely. Assuming it wins approval, I’m really hoping I can get some seedlings in a few years to plant in my forest.
Though, they are still going through the FDA, EPA, and USDA process...
https://www.federalregister.gov/documents/2021/08/06/2021-16...
My uncle and I also usually took hikes in NC to try and find remaining trees with pollen in the wild. From what I understand, the pollen from these few remaining living trees is used to help re-introduce regional biodiversity into the backcrossed American/Chinese hybrids.
Highly recommend going and helping out on the farm if you can spare a week or two, or joining your state chapter if you’ve got one - or sending your kids!
The survivor has 2 branches coming out of trunk each roughly 42" in circumference, it is not as tall as the one in the article but it's probably got similar girth. The tree is at least 70 years old, I'll confirm with the landlord whether he planted it or if it survived from before his time (he's been here approx 90 years, and I know one red oak and an eastern red cedar is older than he is). We do have Chinese/Japanese chestnuts on the grounds here that are more prolific and it's likely the seedlings I have are hybrids, but who knows?
One interesting thing I noted from the American vs. Chinese/Japanese chestnuts is the chestnut weevil does not appear to infect the nuts.
> There used to be about 4 million American chestnut trees in eastern U.S. forests, until chestnut blight (Cryphonectria parasitica) arrived […]
The number is closer to 4 billion with a B[1]
Their range was across eastern North America and I’ve read estimates that they may have been a quarter to a third of the trees in those forests before the blight arrived.
It also makes me wonder. There was an estimated 30-60 million buffalo before colonialism in the Americas. However, those numbers were probably only possible to reach because of human activity driving out other apex predators and becoming themselves the apex predator. Similar story with paw-paws. Though they're not necessarily being threatened by anything currently, their range is decreasing. It turns out humans were essential for its distribution (likely due to other megafauna going extinct). Another example that comes to mind is the "prairie turnip" which as a staple food of many peoples that lived in the grasslands. Despite harvesting being a destructive process, the action actually ended up helping to spread their seeds. Without human harvest we've again seen a decrease in their range. I can also go on about how essential California cultural burns are for most of the "native" ecology, but I'm sure you get the point
Anyways I guess what I'm getting at is: I wonder how much humans played a role in it achieving such a widespread distribution.
There was a recent book called Dark Emu about aboriginal Australian's role in the native landscapes. Early colonists often remarked that the place looked like a giant, well-managed park. Well it turns out they actually did play a huge role in purposeful management of it. They even grew grains in massive monocultural fields that were often even larger than modern agricultural plots. Similarly there's been a ton of recent research into Amazonia and looking at it as a "manufactured landscape" because of how important the purposeful management of it by native peoples was to the ecosystem as a whole
https://www.science.org/content/article/pacific-northwest-s-...
probably more than we know.
Thousands of eyes!
There are many chestnut trees in the town, planted in the gold rush days, I believe. last fall, I gathered enough nuts walk around town to supplement my diet for a few months. The nuts haven't started falling this year.
Of course, these tree survived the blight because they're well outside the range of the Eastern Chestnut. But still, if someone wants to see chestnut trees, they're here and probably in a lot of places where they were planted outside their range.
Here's a story about one in Oregon.
https://acf.org/our-community/news/passing-of-an-iconic-amer...
https://www.atlasobscura.com/articles/podcast-american-chest...
It's a fictional collection of stories, all linked by trees (it makes sense if you've read it).
Beautifully written, and gave me a huge appreciation for trees.
And it was just a really great story in general. Definitely recommend.
I took high school biology in a classroom named after it. The Christmas song always got explicitly recognized for the loss it memorialized. Any worry about invasive exotics got a “next blight” rhetorical flourish. Our elementary school thanksgiving pageant included a chestnut character (it was a coveted costume). In the summer of 2020 the blight vs hoof and mouth was the frame in which COVID could be productively discussed. The list goes on…
Regardless, as one who knew, great recommendation.
Fwiw this is wrong -- it used to be 4 billion.
The interviewer is not for everyone but I thought it was pretty good discussion. https://www.spreaker.com/user/16676611/restoring-the-america...
Is there a good app which lets you input your zip code, maybe also sun exposure and soil conditions, how many feet of width and height you have available, and then where it will spit out a list of well-suited tree specimens with some nice pictures of each?
Of course one-click ordering wouldn’t hurt, but I like to imagine you would still print out a shopping list and head over to the local nursery.
I was thinking for gardens and fruit trees.
I'm particularly interested in well-suited plants because I will inevitably ignore them, and I'm hoping they can thrive without me.
I'm planting figs this fall.
Here’s the 2021 update for the program: https://www.esf.edu/chestnut/progress-report/2021.htm
I have an F1 hybrid American/Chinese hazelnut in its 9th year on my little hobby farm (southern Ontario). It's done ok, no blight ... yet. It's too far from my other chestnuts (Chinese) to get pollinated to produce nuts tho. I keep meaning to get more trees. It's a nice looking tree.
The team behind iNaturalist is like 6 people (though they're hiring! I wanted to apply but it seems like they mostly need help with DevOps)
The genetically pure American Chestnut tree was nearly eliminated by this blight. So backcrossed hybrids and genetically modified varieties of the American Chestnut are exciting, because there's a hope they could return to their former glory in the ecosystem.
This particular tree is a large specimen of genetically pure American Chestnut, growing in the east coast region as well, so a great find for conservation.
In all, hybrids may be great for individuals, but this movement intends to be more selective for restoration purposes.
Edit:
(I also have two seedlings sprouted from chestnuts I gathered a few years back)
