Billions of American chestnut trees once shaped forests across the eastern United States, growing tall and producing abundant nuts—so much so that chestnuts became a holiday symbol in the lyric “chestnuts roasting on an open fire.” By the 1950s, the species had become functionally extinct after an airborne fungal blight and a lethal root rot, leaving restoration efforts struggling against both disease and the pace of breeding.
A new study in Science released Thursday argues that genetic analysis can shorten that timeline by letting breeders identify which individual trees are likely to resist the diseases and grow well. The approach, the paper’s authors say, reduces the gap between generations, allowing disease-resistant traits to be selected and propagated faster than waiting for trees to reach size and face blight in the wild. The American Chestnut Foundation, which wants to return the tree to a native range that once stretched from Maine to Mississippi, frames the strategy as a practical step toward establishing more disease-resistant generations in Eastern forests in the coming decades.
Lead author Jared Westbrook, director of science at The American Chestnut Foundation, said the key shift is the “engine that we’re creating for restoration.” Westbrook’s framing points to the way genetic testing can identify promising offspring before the traits are fully demonstrated, a change intended to speed the accumulation of gains in disease resistance and competitiveness. The foundation also links the effort to the chestnut’s historical role and usefulness: the American chestnut can grow quickly, reach more than 100 feet (30 meters), produce large amounts of nutritious nuts, and provide lumber prized for its straight grain and durability.
The challenge, Westbrook and other researchers describe, is that the American chestnut’s defense against the blight and root rot is not concentrated in a single genetic place. Instead, they say the desirable traits are scattered across multiple spots in the genome, making traditional breeding difficult because selecting for one factor can also bring along linked traits that undermine performance. John Lovell, senior author and a researcher at the HudsonAlpha Genome Sequencing Center, said that the trait complexity means breeders “can’t just select on one thing because you’ll select on linked things that are negative.”
To address that complexity, the study sequenced the genomes of multiple types of chestnuts and then used those genetic data to find where markers correlated with the traits the authors want. The paper describes a breeding goal that combines disease resistance from a chestnut that evolved alongside the relevant diseases with the stature and forest-competitive traits associated with American chestnuts. The research points to the Chinese chestnut—introduced for its valuable nuts—as a source of disease resistance, while acknowledging that it is “isn’t as tall or competitive in U.S. forests” and does not provide the same ecological role as the American species.
Because the method aims to keep American chestnut characteristics while adding disease resistance, the authors describe an explicit hybrid DNA target, roughly 70% to 85% American chestnut DNA. They also describe the role of genetic testing in making breeding decisions earlier: instead of waiting for natural growth and disease exposure to reveal which trees perform best, breeders can use the genetic results to reveal likely winners sooner. In that framing, the narrower generation gap translates into faster progress toward planting more robust trees in the range where American chestnuts historically competed.
Oregon State University professor Steven Strauss, who said he was not involved in the study, told Science readers that the gene-focused approach identified promising genes but also argued for faster options, potentially including editing those genes. In an accompanying commentary piece in Science, Strauss said regulations can bog down these ideas for years, arguing that “People just won’t consider biotech because it is on the other side of this social, legal barrier” and that it is “shortsighted.” His perspective highlights how technological feasibility may still collide with policy timelines for biotech applications in forestry.
The study also raised a question about identity and ecological meaning: how much the American chestnut could change while still being the American chestnut. Donald Edward Davis, author of The American Chestnut, said the species has a “unique evolutionary history” and “a specific place in the North American ecosystem,” adding that “Having that tree and no other trees would be sort of the gold standard.” Davis also described the chestnut as a keystone species supporting other animals, including squirrels, chipmunks, and black bears, and he said he was pleased the study included some surviving American chestnuts but favored relying on them more heavily.
Davis questioned the balance between hybrid approaches and restoring wild American trees, saying, “Not that the hybrid approach is itself bad, it is just that why not try to get the wild American trees back in the forest, back in the ecosystem, and exhaust all possibilities from doing that before we move on to some of these other methods?” Lovell, in turn, said resurrecting the species requires introducing genetic diversity from outside the traditional pool of American chestnut trees, warning that focusing only on American chestnut genes could narrow the genetic pool enough to risk a future genetic bottleneck. He said, “I think if we only select American chestnut (tree genes), period, there’s going to be too small of a pool and we’re going to end up with a genetic bottleneck that will lead to extinction in the future.”