Mark Alexander, Conservation of Castanea Dentata Genetic Resources of the Southeastern United States
Faculty Chair: Dr. Hill Craddock
The ongoing effort by the American Chestnut Foundation to breed and reintroduce a blight resistant, locally adapted variety of American chestnut (Castanea dentata) requires a broad genetic base. To ensure adequate genetic diversity, genetic resources must be collected from throughout the native range of the species. Finding and breeding surviving C. dentata stump sprouts is problematic due to the relatively short life span of blooming stems and their often remote forest habitat. To facilitate more efficient location of surviving trees in the southeastern U.S., we used a Geographic Information System (GIS) to overlay soil, topography, and satellite imagery for the generation of predictive, site-specific, chestnut-range maps, as well as a geo-referenced attribute database. We implemented a combination of conservation procedures including both in situ efforts to promote favorable habitat conditions for survivors and ex situ techniques such as traditional breeding, grafting, and orchard repositories. From 2002 to 2004 our efforts resulted in the location of 14 surviving, seed-bearing, C. dentata in Tennessee. We bred these wild trees using C. dentata and hybrid pollens resulting in the capture of native southern germplasm into the national breeding program. In 2004 we also located and graft-propagated 18 different non-blooming C. dentate trees for inclusion in the breeding orchards. The winter of 2004-2005 was marked by the establishment of the first complete backcross family orchards in Tennessee, which were planted with progeny from our 2002 and 2003 gene-conservation efforts.