Genetically engineered American chestnut clears first federal regulatory hurdle toward restoration
核心洞察
A genetically engineered, blight-tolerant American chestnut (搜索) has received the first of several required approvals from U.S. federal regulatory agencies, a milestone toward distributing trees for restoration.
The tree carries a single wheat-derived gene that helps it tolerate chestnut blight (搜索) by reducing damage rather than repelling the fungus.
Researchers hope to begin distributing trees within a few years, though landscape-scale restoration is expected to take decades.
A genetically engineered, disease-tolerant American chestnut (搜索) has cleared the first of several approvals required from U.S. federal regulatory agencies, marking a milestone in the century-long effort to restore a tree that once dominated eastern forests from Maine to Mississippi.
Andrew Newhouse, director of the American Chestnut (搜索) Research and Restoration Project at the State University of New York, confirmed the regulatory milestone in an interview. "We received the first of a few different approvals from U.S. federal regulatory agencies that we would need in order to start distributing these trees and start using them for restoration," Newhouse said.
The American chestnut (搜索) was a dominant and iconic species in many Appalachian forests until it was devastated by an introduced fungus from Asia called chestnut blight (搜索). A majestic forest tree, an American chestnut was typically 50 to 100 feet (15 to 30 meters) in height, but could grow as tall as 150 feet (45 meters) over its several-hundred-year lifespan. Its leafy canopy provided shade and beauty, while its nuts nourished wildlife, Indigenous peoples and European settlers alike, and its rot-resistant wood was prized for lumber.
People first noticed the blight fungus in New York City in 1904, when it began killing trees at the Bronx Zoo. Over subsequent decades, it spread south and east through the chestnut's range, killing nearly every mature tree in its path.
A single wheat gene for blight tolerance
The genetic engineering approach centers on inserting a single gene from bread wheat into the American chestnut (搜索). This gene encodes a protein called OXO (搜索), short for oxalate oxidase, which breaks down oxalic acid — the fungus's key weapon for invading and killing plant tissues.
Newhouse emphasized that the gene does not confer resistance in the traditional sense. "It's not actually a gene for resistance, we would say. It helps the trees tolerate the blight. So instead of repelling the blight fungus or preventing the trees from getting the disease, this just reduces the amount of damage that the blight causes to the trees," he explained.
This work was pioneered by the late William Powell and his colleagues in the College of Environmental Science and Forestry at the State University of New York in Syracuse. For about 20 years, it appeared the OXO (搜索) gene could produce fully blight-resistant and healthy chestnuts.
Why genetic engineering over traditional breeding
Newhouse addressed why conventional crossbreeding has not been sufficient. "Traditional breeding is actually a lot more complicated in this case because there's so many different genes that go into blight resistance. And so keeping track of all of those different genes and making sure they all end up in the same individual is a lot more complicated than just adding a single gene," he said.
Resistance is exceedingly rare in the American chestnut (搜索) itself, so breeders have historically relied on hybridization with the naturally resistant Asian chestnut, recrossing hybrids with American chestnut and selecting blight-resistant offspring that resemble American chestnuts in growth and form. However, progress had been limited.
Addressing safety concerns
Acknowledging that genetically modified organisms remain controversial, Newhouse pointed to the depth of research behind the project. "I would say we have done a lot of research — our team with the chestnut tree and many other labs. So we do understand a lot about how these organisms work in their environment. The regulatory agencies have reviewed this in great detail. And so I think these are actually some of the most-studied trees," he said.
A gradual path to restoration
Newhouse cautioned that restoration will unfold over an extended timeline. "I do want to acknowledge it'll be a gradual process. It won't suddenly restore American chestnuts across their whole original range, but we will be able to see this and be able to have hope, I think, for protecting other trees as well," he said.
He indicated that distribution could begin relatively soon. "We're hoping to be able to start distributing trees within a few years. But like I said, this is going to be a gradual process and will really take decades before we start seeing kind of landscape-scale changes," Newhouse said.
Beyond the chestnut itself, the project carries broader significance for conservation science. "This project, using biotechnology, is really a unique approach and offers, I think, a lot of hope in light of threats to not only American chestnuts, but also other important native trees," Newhouse said.