Prior to its demise in the early 1900s from two introduced disease agents (Phytophthora root rot and Cryphonectria blight), the American chestnut (Castanea dentata) was one of the most important trees of the eastern deciduous forests. Some estimates suggest that approximately 25% of all trees within the Appalachian mountains were chestnuts. Their large size and annual production of high quality nuts made the trees a “foundation” species within many natural communities. Moreover, humans found these trees enormously beneficial as sources of food, timber, and other uses, and thus the tree had considerable cultural and economic importance. This all ended by the 1950s when populations of around 4 billion trees were reduced to a few hundred million, most of which were small sprouts rather than large, productive trees.
For over 30 years, The American Chestnut Foundation (TACF) has worked toward restoring this species using methods that introduce disease resistance and also by developing strategies and a network of partnerships necessary to reintroduce the trees to the wild. In such a restoration project, capturing the genetic diversity present throughout the species’ range is an important component in addition to the development disease resistance.
This talk will describe TACF efforts being taken in the state of Georgia and other southern states to preserve genetic diversity of American chestnut and to introduce disease resistance into the trees. Focus will be on classical breeding which introduces resistance genes from Chinese chestnut (C. mollissima), genetic engineering whereby resistance genes are introduced directly into American chestnuts, and modification of the blight fungus to weaken its virulence. This three-pronged approach has been titled the 3-BUR model (Breeding, Biocontrol, and Biotechnology United for Research) and will involve significant collaboration among various TACF chapters and other entities, especially SUNY-ESF where the first American chestnuts with high blight resistance have been developed.
Dr. Martin L. Cipollini is the Dana Professor of Biology at Berry College, Mount Berry, Georgia, where he teaches undergraduate courses such as Principles of Microbiology, Botany and Ecology, Forest Ecology and Tropical Ecology (Costa Rica/Cuba). He received B.S. and M.S. degrees in Biology from Indiana University of Pennsylvania, and a PhD. in Ecology from Rutgers University. A faculty member at Berry College since 1995, his current research activities revolve around the college’s Longleaf Pine and America Chestnut projects. In his role as science coordinator for the Georgia Chapter of TACF, he has helped establish numerous chestnut orchards across the state. He is currently working with UNG on plans to establish a Phytophthora field test orchard at the university’s Hurricane Creek site.