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American chestnut tree in Centreville is the 'holy grail' for conservationists

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Re: American chestnut tree in Centreville is the 'holy grail' for conservationists

#91

Post by empyrrhicist »

culi wrote: post #77
JshWright wrote: post #55

Earlier quoted context omitted.

It actually is pretty "simple" in this case (the tree needs to produce a single chemical, oxalate oxidase). There is a program that has done this very successfully, and it just working through the regulatory process before wider distribution can happen. They have thousands of trees in (controlled) forest plots, including three generations of offspring.

That's very interesting. The video I linked showed that blight resistant trees had a very specific response to grow extra tissue around the infection site to stop it from spreading further so I assumed it was more of a multi-pronged defense

Yes - the Asian ones that evolved with the fungus have a more complex strategy, making a purely breeding-based program challenging. Separately, some clever genetic engineering allows the trees to break down oxalic acid, which prevents the fungus from being able to efficiently attack the plant cells.

Two separate things.

Re: American chestnut tree in Centreville is the 'holy grail' for conservationists

#92

Post by canjobear »

space_fountain wrote: post #30
echelon wrote: post #8

Earlier quoted context omitted.

Why don't they use agrobacterium transfection, gene guns, or molecular techniques to directly transfer the resistance genes over? Do we not know what the genes themselves are? 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.

There is actually a parallel technique nearing the finish line that does sort of this. The gene they moved though is from wheat not another tree species, but still seems to give great blight resistance. Currently the barrier to it is entirely regularity. I believe it would be one of the first plants approved to just be released into the wild without something to prevent it reproducing naturally. The normal anti genet…

What authority can enforce approval or disapproval to release something into the wild? Suppose I own land next to a national park. Then can’t I plant whatever I want on that land, trusting that it will spread into the park?

Re: American chestnut tree in Centreville is the 'holy grail' for conservationists

#93

Post by Cupertino95014 »

tsol wrote: post #48
nebul wrote: post #21

Earlier quoted context omitted.

For anyone wanting to learn more about this breeding technique, it's called backcrossing[1]. It's also used for agricultural crops, but requires many generations. [1] https://en.wikipedia.org/wiki/Backcrossing

Simple, yet effective. I've heard it said modern fruits are relatively tasteless compared to their older counterparts because they are bred for size and hardiness. I wonder if these can be backcrossed as well to produce more flavorful fruits with similar sizes

Interesting. I love nuts of all types, but not the chestnut. It's really more like a small potato than a nut. I wonder if the old ones tasted better.

Re: American chestnut tree in Centreville is the 'holy grail' for conservationists

#94

Post by audiodude »

culi wrote: post #5

Saw this really amazing video[0] the other day about American Chestnut Foundation's breeding program in Virginia to revive the American chestnut 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…

I hate these awful GMO trees! Why can't we have certified USDA Organic trees anymore!

Re: American chestnut tree in Centreville is the 'holy grail' for conservationists

#95

Post by robwwilliams »

audiodude wrote: post #94
culi wrote: post #5

Saw this really amazing video[0] the other day about American Chestnut Foundation's breeding program in Virginia to revive the American chestnut 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…

I hate these awful GMO trees! Why can't we have certified USDA Organic trees anymore!

Assume this is a joke, right? Have to add the ;-) even for nominally bright people.

Re: American chestnut tree in Centreville is the 'holy grail' for conservationists

#96

Post by robwwilliams »

nebul wrote: post #67
tsol wrote: post #48

Earlier quoted context omitted.

Simple, yet effective. I've heard it said modern fruits are relatively tasteless compared to their older counterparts because they are bred for size and hardiness. I wonder if these can be backcrossed as well to produce more flavorful fruits with similar sizes

The hard thing with taste is that it's usually the sum of many quantitative traits, each one being governed by several genes which can be located on different chromosomes, as seen in tomato[1]. Transferring enough of them into the modern genome through backcross would probably require a crazy amount of generations... or a crazy amount of luck :) [1] https://doi.org/10.1093/jxb/erf058

You would need to map the relevant loci and then use a speed congenic selection strategy. Done in mice easily. Mapping the loci modulating traits like disease resistance or taste is the hard part.

Re: American chestnut tree in Centreville is the 'holy grail' for conservationists

#97

Post by robwwilliams »

echelon wrote: post #8
culi wrote: post #5

Saw this really amazing video[0] the other day about American Chestnut Foundation's breeding program in Virginia to revive the American chestnut 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…

Why don't they use agrobacterium transfection, gene guns, or molecular techniques to directly transfer the resistance genes over? Do we not know what the genes themselves are? 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.

They probably have no firm idea about the key genes involved in resistance. There could be half a dozen.

Re: American chestnut tree in Centreville is the 'holy grail' for conservationists

#98

Post by robwwilliams »

canjobear wrote: post #92
space_fountain wrote: post #30

Earlier quoted context omitted.

There is actually a parallel technique nearing the finish line that does sort of this. The gene they moved though is from wheat not another tree species, but still seems to give great blight resistance. Currently the barrier to it is entirely regularity. I believe it would be one of the first plants approved to just be released into the wild without something to prevent it reproducing naturally. The normal anti genet…

What authority can enforce approval or disapproval to release something into the wild? Suppose I own land next to a national park. Then can’t I plant whatever I want on that land, trusting that it will spread into the park?

These are not GMO plants—just selectively bred plants. This is similar to almost all domestic animals and most plants.

Re: American chestnut tree in Centreville is the 'holy grail' for conservationists

#99

Post by hprotagonist »

culi wrote: post #84
helen___keller wrote: post #59

The article misstates > 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. 1 https://en.m.wikipedia.org/wiki/Am…

Astounding. Crazy to think about 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 decr…

> I wonder how much humans played a role in it achieving such a widespread distribution.

https://www.science.org/content/article/pacific-northwest-s-...

probably more than we know.

Re: American chestnut tree in Centreville is the 'holy grail' for conservationists

#100

Post by jonstewart »

subpixel wrote: post #86
culi wrote: post #5

Saw this really amazing video[0] the other day about American Chestnut Foundation's breeding program in Virginia to revive the American chestnut 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…

The genetic modification the ACF is doing is actually very controversial among the community of people commuted to restoring fruit and nut biodiversity. I just saw Eliza Greenman speak on this subject, never expected that to circle back to HN.

Backcrossing/“breeding” is relatively uncontroversial and not considered GMO — though it may be controversial whether the eventual derived breed is a true American Chestnut.

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.

https://www.esf.edu/chestnut/genes.htm

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