In the eastern United States, the American chestnut was once a dominant tree—growing tall, producing large quantities of nuts, and turning up each year as part of the season’s familiar imagery. But by the 1950s, the species had been knocked back toward functional extinction after a lethal combination of diseases, including a fungal blight spread by air and a damaging root rot.
A new study published Thursday in Science reports a potential way to speed up efforts to bring the American chestnut back. The researchers said they can use genetic testing of individual trees to find which ones are more likely to survive disease and reach a large size, with the goal of accelerating the planting of the next generation rather than waiting for traits to show up naturally over time.
Jared Westbrook, the study’s lead author and director of science at The American Chestnut Foundation, said the key advance is the restoration-focused “motor” the group is building with the new genetic approach. The foundation seeks to return the American chestnut to its native range, which once stretched from Maine to Mississippi.
The American chestnut can grow quickly and, the study’s reporting notes, can reach more than 30 meters (100 feet). It also produces abundant, nutritious nuts and provides valuable wood due to its straight grain and durability—traits that made the tree central both to people and to ecosystems in the eastern forests.
The study’s authors and an accompanying reviewer describe why the restoration challenge has been so difficult: American chestnuts have had few defenses against the foreign diseases that affected them. They point to the Chinese chestnut as one source of disease resistance, but they also say it does not match the American chestnut’s competitiveness in U.S. forests or its historic role supporting other species.
Researchers said they are therefore pursuing trees that combine disease resistance with American-chestnut characteristics. They said the traits involved are spread across many places in the genome, making it hard to select for one desired feature without also selecting for linked traits that could be harmful, which can leave trees shorter and less competitive if selection focuses only on resistance.
To address that problem, the researchers sequenced the genomes of different chestnut types and mapped many genetic points linked to desired traits. They said the breeding approach can keep high proportions of American-chestnut DNA—roughly between 70% and 85%—while using genetic information to identify promising offspring earlier than would be possible from growth and disease exposure alone.
In a separate assessment, Steven Strauss, a professor of forest biotechnology at Oregon State University who was not part of the study, said the Science paper identifies some promising genes. Strauss said he wants researchers to be able to edit those genes, describing it as a possibly faster and more precise path to a better tree; he also said regulations could slow such work for years.
Strauss said the public may not embrace the biotechnology because it faces social and legal barriers, and he called that view “a vision” that he said misses how the technology could help. Another perspective came from Donald Edward Davis, author of The American Chestnut, an Environmental History, who said the American chestnut has a unique evolutionary history and a specific place in North American ecosystems.
Davis described the tree as a “gold standard” species for its ecological role, saying it mattered to humans and was vital for wildlife including squirrels, listed squirrels, and black bears. He said he was pleased that the study included some American chestnut survivors, but he questioned approaches that may rely more heavily on hybrids—arguing instead for maximizing the chances that wild American trees can return to the ecosystem before shifting toward other methods.
The study’s authors said restoring the species will require introducing genetic diversity from outside the traditional American chestnut gene pool. They said their goal is high, disease-resistant trees and that they are optimistic, while also framing the work as part of a longer-term effort that could unfold over decades if the genetic selection strategy works as intended.