Altered chestnut trees succeed

In stands of tiny trees in North Carolina, Tennessee and Virginia blooms the hope of restoring a mighty giant, as scientists try to bring back the American chestnut from near extinction.

Five hundred blight-resistant American chestnut saplings are thriving a year after they were planted in three national forests, a milestone in the long-term effort to re-establish the tree in its native habitat. Reviving the chestnut, decimated by a fungus, would reverse one of the worst ecological disasters in the nation's history, reviving a major source of food and lumber that forest animals and humans have missed for more than a century.

The cutting-edge genetic research that offers the promise of a blight-resistant hybrid could, if successful, also be used to stop the damage to U.S. forests by other exotic pests, such as bark beetles, the woolly adelgid and Dutch elm disease.

"If it works, there is a long line of similar ecological problems that are waiting for similar kinds of solutions," said Ron Sederoff, a professor in the Department of Forestry and Environmental Resources at N.C. State. "There are 100 different threatened trees in our American forest, and each one has a disease or a pest that potentially could do as much damage as the blight did to the American chestnut."

Sederoff leads a project to map the genome of the chestnut tree so researchers can create trees that are nearly pure American chestnuts but have the handful of genes from the Chinese chestnut that make that tree resistant to blight. Meanwhile, others are doing a different kind of genetic research, cross-breeding different varieties of trees and growing them in labs, nurseries and test plots to see how they fare.

"Just developing a blight-resistant tree is not enough," said Bryan Burhans, who heads the American Chestnut Foundation in Asheville. The trees have to be planted in the forest to see if they can survive real-world conditions.

Researchers from the foundation, along with the U.S. Forest Service and the University of Tennessee, announced Wednesday that 500 trees planted in experimental plots in three national forests have done well in their first year in the wild. The trees were about a year old and 3 to 5 feet tall when planted. If they succeed in the long term, the trees will help experts determine whether they're on the right track.

The test planting is an important step in a reintroduction process that began more than 50 years ago, when a UT geneticist tried to propagate chestnut trees that wouldn't succumb to blight, Scott Schlarbaum, professor of forest genetics and director of the Tree Improvement Program at UT, said Wednesday.

This work, Schlarbaum said, is "the beginning of restoring an old friend to eastern North American forests."

American chestnuts can still be found; the blight attacks the tree's vascular system but doesn't affect its roots, so new trees continue to sprout. By the time they're 10 years old, though, the fungus strikes again.

It will be five to 10 years before researchers know whether the saplings will survive. Eventually, researchers hope to develop hybrids that are genetically related to native types from each area where they are planted, to give them the greatest chance of survival.

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