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American Chestnut

Forest biologists are seeking federal approval from the FDA, USDA and EPA to reintroduce an almost-extinct species — the American chestnut — back into the forests of the eastern United States. The scientists have genetically modified the trees to resist the devastating Chestnut blight that over the last 100 years has almost killed every nut-bearing American chestnut tree on the planet.

William Powell, Charles Maynard and their colleagues from the State University of New York College of Environmental Science and Forestry (SUNY-ESF), have taken genes from wheat, Asian chestnuts, grapes, peppers and other plants to create hundreds of transgenic trees that are almost 100 percent genetically identical to wild American chestnut trees yet immune to the chestnut blight, or Cryphonectria parasitica. 

Over the next 5 years, the team expects to grow 10,000 blight-resistant American chestnut trees and, with the help of volunteers and landowners, reintroduce them into private and public woodlands of New York and the rest of eastern United States, reclaiming mine sites, populating historic sites, and making them available to the public.

Before the early 1900s, one in every four hardwood trees in North America’s eastern forest was an American chestnut. An important source of food, shelter, and naturally rot-resistant timber, the American chestnut was considered a “keystone” species, providing critical and valuable habitat.

Starting in the late 1800s, an exotic blight pathogen from Asia killed 3 to 5 billion American chestnut trees, nearly wiping out the tree that had shaped the Eastern U.S. forest ecosystem for centuries. The fungus releases oxalic acid that kills nearby tree tissue, providing a conducive environment for the fungus to spread further. The dead tissues, called cankers, essentially strangle the tree.

“The wheat gene in the transgenic trees codes for an enzyme that detoxifies oxalic acid. Without the acid to kill the tissue, the fungus can’t move in,” says Powell. “If you eat wheat, you’re eating oxidate oxalic genes and you’re most likely also eating the enzyme that it produces.” Powell notes that genetically engineered chestnut trees do not kill the fungus, but are better able to defend themselves against the fungus.

The SUNY-ESF team does not intend to patent the transgenic trees, nor will they profit from their reintroduction. In several years, Powell hopes the chestnut trees will be deregulated, ready to plant and eat.

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