The American chestnut, a tree that in its time was highly versatile and prevalent, is struggling from its long battle with the blight fungus.
The virus, an Endothia parasitica fungus, came to America through imports from Asia. The earliest case was cited in 1904, and by the 1950s, nearly every tree was infected.
Sara Fern Fitzsimmons, chestnut regional science coordinator supervisor at Penn State and tree breeding coordinator for the American Chestnut Foundation, said the tree is not extinct but is highly susceptible to infection.
Fitzsimmons works to breed trees with genes that aren’t as susceptible to the fungus. She said they started with a base population of about 500 trees and are breeding new stock all the time.
“We’ve taken a lot of pain and effort, a lot of resources to restore diversity back into this population,” she said. “This is the population that we’re going to use for the entire species from here on out.”
Fitzsimmons said that each year they start at step one to bring in more diversity. She said they don’t want blight to figure out how to take over the new population of trees.
“It’s not likely, but we don’t want to take that chance,” she added.
Kim Steiner, professor of forest biology and director of The Arboretum at Penn State, said those at Penn State are working to find which genes are strong and to consolidate the resilient traits.
Steiner said they’ve been looking at the Chinese chestnut trees because this species is not affected by the fungus. He said they hope to develop trees to have strong American chestnut characteristics with some of the Chinese tree’s blight-resistant genes.
Meanwhile, Penn State professor of molecular genetics John E. Carlson said he has been working in parallel with Fitzsimmons and others involved in the chestnut research. “Our goal is to have markers that can be used at the DNA level,” he said.
Fitzsimmons said that while there may be some healthy competition through the two groups, they do share information. “We’re all going towards the same goal,” she said. “Our goal is to restore a species.”