After years of ups and downs, the attempt to resurrect the American chestnut tree, once the glorious king of eastern forests, has taken another turn: An important federal agency has given the go-ahead to using genetically modified trees rather than species created by cross-breeding.
But the project still has obstacles to overcome, including those of its own doing.
The big news is that the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) recently ruled that the Darling-54 tree, a GMO tree developed at State University of New York’s forestry school, is safe to release into the wild because it poses no greater risk to the environment than the unmodified American chestnut tree.
The EPA must still approve the idea, but the inspection service was seen as the bigger obstacle because it had never before OK’ed the release of a GMO tree species.
For more than 15 years, I’ve been writing about efforts to bring back the American chestnut, which was such a useful tree, with superb wood and generous production of nuts for wildlife, that some early colonists decided it was obviously placed here by God to help them. Although chestnuts made up a third of the forest in parts of the Northeast, the species was virtually wiped out in the 20th century by a fungus accidentally imported from Asia, with some help from an imported root disease.
People have been trying to create a resistant version for decades by cross-breeding the occasional young surviving American chestnut tree (including one on my street) with Chinese chestnut trees, which mostly shrug off the blight. A similar cross-breeding effort, incidentally, is being done with American elm trees in an effort to create an elm that can survive the blight which wiped out that tree in North America.
Neither of these cross-breeding efforts has really worked, however, which is why scientists at SUNY ESF tried the genetic-modification route. The result is the Darling-54 tree, named after an early supporter of the program and the position that the imported gene takes on the tree’s chromosome. The imported gene, taken from grasses, nullifies acid produced by the fungus and seems to protect the tree although it also has some effect on growth and other viability.
This is where the self-inflicted wound arrives.
A couple of years ago ESF was close to getting approval for release of the Darling-58 tree — notice the number — much to the excitement of many people. Fans included many but not all chapters of the American Chestnut Federation, which has been raising hybrid trees in orchards, including some in New Hampshire. The project was so close to fruition that I wrote a column in late 2023 about the best way to go about planting the Darling-58 trees to speed up reintroduction.
However, at just about that time, Prof. Thomas Klak of the University of New England, who has been working with the chestnut program for years, found that the imported gene had attached itself to a different part of the chromosome than was thought. Virtually all the trees that have been growing and tested were actually Darling-54, not Darling-58, so the data on their success and danger was useless.
That scuttled the approval process and supercharged suspicions about the wisdom of releasing any GMO tree into our forests. The American Chestnut Foundation, for example, is strongly opposed to the Darling-54 release. They argue that cross-breeding guided by computer models of tree DNA, a process called recurrent genomic selection, is a safer bet.
As a further complication, ESF is working on a different GMO chestnut called DarWin that avoids some of the pitfalls of Darling-54. As I understand it, the main issue is that Darling-54 fights the fungal acid even when it’s not present, which drains tree resources unnecessarily, while DarWin and Darling-58 only react to acid when it is around.
I’m not quite sure what all this means about my long-held hope to plant blight-resistant chestnut seedlings out behind the barn. Trump’s gutting of federal agriculture and research facilities and staff means little sensible guidance is likely to come down from on high, and there’s so much divided opinion among amateurs and professionals interested in the topic that it could easily prevent much happening despite the inspection service’s approval.
But you never know. Maybe there will be recognizable chestnut trees gracing New Hampshire’s woodlands by mid-century. One can only hope.
