The American chestnut may get a do-over. With a significant new round of grants, The American Chestnut Foundation, based in North Carolina, plans to develop ways to predict chestnut trees’ resistance to diseases that cause chestnut blight and root rot. This method, known as “genomic selection,” is expected to accelerate selection of the most disease resistant trees from the groups breeding program.
“If we can develop genomic tools to restore American chestnut, we can do this with almost any forest tree species imperiled by the introduction of invasive pathogens” said project partner Jeremy Schmutz, director of the American chestnut genome project at HudsonAlpha, in a statement.
Chestnut blight arrived from Asia in the early 1900s and quickly reduced an estimated 4 billion American chestnut trees to root sprouts. Phytophthora root rot eradicated American chestnut from forests in the southeastern Piedmont region prior to the introduction of chestnut blight.
The loss of American chestnut impacted other species, significantly reducing the population of bear, Eastern wild turkey and pollinators in forests of the eastern United States.
For some 30 years, the Chestnut Foundation has been attempting to breed resistance into American chestnut from Chinese chestnut, which is resistant to these diseases. The major bottleneck in the foundation’s breeding program has been in screening the thousands of trees needed to combine the right mixture of blight-resistance and American chestnut traits.
The first step in assessing a tree’s resistance, according to a media release from The American Chestnut Foundation, is to artificially inoculate it with the fungus that causes chestnut blight. After the most susceptible trees are culled, additional selections are made by screening descendents of the remaining trees for disease resistance. Using this method at the current rate of seed production, it would take more than 30 years to complete selection.
Genomic selection would reduce the time necessary to complete the selection of disease-resistant parents to five years. Genomic selection doesn’t create Franken Nuts. Using high quality reference genome sequences for American and Chinese chestnut species, it sequences individual genes involved in disease resistance.
Researchers want to know why the Chinese and American chestnut species differ so much in their resistance to blight and root rot. Collaborators at Pennsylvania State University are assembling a reference genome sequence for Chinese chestnut. With the recently awarded funding, collaborators at HudsonAlpha Institute for Biotechnology, a nonprofit genomics and genetics research institute in Alabama, intend to lead a parallel effort to assemble a reference genome sequence for American chestnut.
“Restoring a species is a hopeful and ambitious undertaking,” said said American Chestnut Foundation president and CEO Lisa Thomson, in a statement. “We are thankful these private family foundations have invested in a plan for reintroduction of a resistant American chestnut tree, once one of the most important hardwood trees in the Eastern forests.”
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