The seedlings that were placed into the ground came from generations of backcross breeding that date to the early 1980s. Matt Brinckman, the American Chestnut Foundation’s Mid-Atlantic Regional Science Coordinator, said the project began by crossing an American chestnut with a Chinese chestnut, which is resistant to the blight. The hybrids that were in turn resistant to the blight were crossed again with American chestnut — and again and again until scientists obtained a crossbreed that was 15/16 American chestnut and only 1/16 Chinese chestnut.

The American Chestnut Cooperators’ Foundation was co-founded by Gary Griffin, a plant pathologist at Virginia Tech. Instead of crossbreeding, that group has focused on finding the few remaining large American chestnut trees that have demonstrated partial blight resistance.

“We try to interbreed those to obtain greater levels of blight control,” Griffin said. “There aren’t many of these specimens, but we’ve found them and have been working with them for more than 30 years.”

http://www.roanoke.com/news/roanoke/wb/317311

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