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Thu Apr 30, 2020, 09:00 AM

Geneticists May Have Turned The Corner On Restoring American Chestnut - Long, Fascinating Story

EDIT

Darling sought support from the American Chestnut Foundation, a nonprofit started in the early 1980s. Its leaders told him to get lost, basically. They were committed to crossbreeding and were wary of genetic engineering, which was already attracting opposition from environmental activists. So Darling created his own nonprofit to fund the genetic engineering work. That organization wrote its first check to Maynard and Powell, for $30,000, Powell says. (In 1990, the national organization reversed itself and accepted Darling’s splinter group as its first state chapter, but some members remained skeptical or outright hostile toward genetic engineering.)

Maynard and Powell went to work. Almost immediately, their estimated timeline proved unrealistic. The first hurdle was figuring out how to grow chestnuts in the lab. Maynard tried mixing pieces of chestnut leaf with growth hormones in round, shallow plastic petri dishes, a method used to grow poplar trees. It proved impractical. Nor would new trees grow from specialized cells that develop into roots and shoots. “I’m the world’s leading authority on how to kill chestnut trees,” Maynard says. A University of Georgia researcher, Scott Merkle, eventually taught Maynard how to grow chestnuts from embryos, the next developmental stage after pollination.

Finding the right gene — Powell’s job — also proved challenging. He spent several years studying an antimicrobial compound based on a frog gene but abandoned it over fears that the public might not accept a tree imbued with frogginess. He also looked for a blight-resistance gene in the Chinese chestnut, only to discover that numerous genes are involved in protecting the tree (at least six that they identified). Then, in 1997, a colleague returned from a scientific meeting with a listing of abstracts and presentations. Powell noticed one titled “Expression of Oxalate Oxidase in Transgenic Plants Provides Resistance to Oxalic Acid and Oxalate-Producing Fungi.” From his virus research, Powell knew that the blight fungus exudes oxalic acid to kill chestnut bark and make it digestible. If the chestnut could produce its own oxalate oxidase, a specialized protein that breaks down oxalic acid, it might be able to defend itself, Powell realized. “That,” he says, “was my eureka moment.”

Many plants, it turns out, have a gene that allows them to produce oxalate oxidase. From the researcher who gave the talk, Powell got its wheat variant. A graduate student, Linda Polin McGuigan, refined a “gene gun” technique that fired the gene into chestnut embryos, hoping it would slot into the embryonic DNA. The gene lodged in the embryos temporarily, but then vanished. The team abandoned that approach and turned to a bacterium that long ago evolved a way to snip other organisms’ DNA and insert its genes. In nature, the microbe adds genes that force the host to make bacterial food; geneticists had hacked the bacterium so that it would insert any gene a scientist wanted. McGuigan got it to reliably add to chestnut embryos both the wheat gene and a marker protein that, when illuminated under a microscope, produces green light as a sign that the insertion has succeeded. (The team quickly stopped using the marker protein — nobody wants a tree that can glow.) Maynard calls the method “the most elegant thing in the world.”

EDIT

https://www.nytimes.com/2020/04/30/magazine/american-chestnut.html

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Response to hatrack (Original post)

Thu Apr 30, 2020, 09:07 AM

1. i'm glad that splinter group worked out

i wonder of they have a branch nearby?

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Response to rampartc (Reply #1)

Thu Apr 30, 2020, 09:14 AM

3. They were asked to leaf but proved to be a hard nut to crack.

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Response to hatrack (Original post)

Thu Apr 30, 2020, 09:07 AM

2. This is fascinating research!

My family settled in the mountains of Western North Carolina in the mid 1700s. I have a plain table that is made of chestnut wood. Apparently, it was made by a family member. It was old when my mom was a little girl. My mom ate at that very table when her family lived with her grandmother, my great grandmother, back in the late 1930s to early 1940s. i have the table now. It has wooden pegs.

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Response to CottonBear (Reply #2)

Thu Apr 30, 2020, 09:54 AM

5. Is there any way you could post a picture of your chestnut wood table?

That would be awesome!

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Response to hatrack (Original post)

Thu Apr 30, 2020, 09:45 AM

4. I don't have time at the moment to read this

but I wanted to just remark that this is amazing and such good news! Thank you for posting it.

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Response to hatrack (Original post)

Thu Apr 30, 2020, 09:55 AM

6. I have friends that have a chestnut farm. The history of chestnuts in the USA is really

interesting. Thanks for posting this!

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Response to hatrack (Original post)

Thu Apr 30, 2020, 10:26 AM

7. people should check themselves when questioning science they dont really understand.

 

people barking about gmo's who cant even tell you what the letters mean should be thoroughly ignored. always.

great story. i think i could find room for a chestnut.

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Response to hatrack (Original post)

Thu Apr 30, 2020, 12:45 PM

8. I personally would welcome

a tree imbued with frogginess.

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Response to pscot (Reply #8)

Thu Apr 30, 2020, 06:24 PM

10. Yes. And the green glowing one sounds cool!

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Response to hatrack (Original post)

Thu Apr 30, 2020, 01:21 PM

9. I have followed this very closely. I had a 20 ft American Chestnut in my yard which I'd hoped...

...was resistant; the former owners of my house may have been involved with the ACF work - they would send you seeds if you contributed enough.

My tree, however died.

I have been interested in the SUNY-ESF work in the past, but have not kept up with it.

If this holds up, it's really wonderful. I always hoped that this GMO approach would work, and I did hear that SUNY ESF had a field trial underway, and was hoping Greenpeace didn't cut the trees down in the night.

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