Blight Resistant American Chestnuts

Submitted by Lucas Machia.


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For over 22 years, Maynard and Bill Powell, co-directors of the College of Environmental Science and Forestry's American Chestnut Research and Restoration Center, have attempted to engineer American chestnut trees with resistance to a specific blight that has left the species almost completely extinct by the start of the 20th century. One group of trees, all clones of a cell referred to as "Darling 4," show strong resistance to the fungus.

The Darling 4 is one of 17 different genetically engineered cells that include a gene from wheat known as oxalate oxidase. While the gene does not kill the fungus, it does protect the tree from damage, Maynard said.

“Oxalate oxidase doesn’t harm the [fungus], but it will starve it,” explained Maynard. “It deactivates the acid that kills the plant, forcing the fungus to go back to being a bark parasite on the surface of the bark.”

The ultimate goal of the Research and Restoration Center is to plant thousands of fully blight-resistant trees in American forests across the country that will slowly repopulate the forests.  Powell estimates it will take about 100 years from the time the first tree is planted outside of a research station to the time the forests are fully repopulated.

 “It’s unrealistic to think we can plant enough trees to restore the ecosystem to how it used to be without letting them multiply on their own,” said Powell.  “Instead, we can plant them in memorable places in order to recreate what the scene looked like in the past, such as during the Civil War.”