Title: Blight-resistant American chestnut trees: selection of progeny from a breeding program

Author: Hiremath, Shiv; Lehtoma, Kirsten; Hebard, Fred

Year: 2007

Publication: In: Gottschalk, Kurt W., ed. Proceedings, 17th U.S. Department of Agriculture interagency research forum on gypsy moth and other invasive species 2006; Gen. Tech. Rep. NRS-P-10. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station: 54.

Abstract: Introduction of the fungus Cryphonectria parasitica into North America in early 1900s resulted in the demise of the American chestnut, which was once the most dominant forest tree in the eastern United States. While the American chestnut (Castanea dentate) is susceptible, its counterpart from Asia, the Chinese chestnut, is resistant to the blight-causing fungus. Researchers attempting to restore the American chestnut have focused both on the eradication of the fungus as well as on breeding blight-resistant chestnut trees. Although crosses between the American and the Chinese yield a blight-resistant progeny, often the hybrids have the characteristics of the Chinese tree, which is a dwarf and lacks the superior timber qualities associated with the American chestnut. Therefore, researchers have been using a "back-crossing" technique where the resistant hybrids are successively backcrossed to the original American tree in order to flood more American genes into the hybrid. By repeated back-crosses, it will be possible to generate a blight-resistant chestnut having all the superior traits of the American chestnut.