© 2005 Heron Publishing—Victoria, Canada
Improving disease resistance of butternut (Juglans cinerea), a threatened fine hardwood: a case for single-tree selection through genetic improvement and deployment
Charles H. Michler (1, 2), Paula M. Pijut (1), Douglass F. Jacobs (3), Richard Meilan (3), Keith E. Woeste (1) and Michael E. Ostry (4)
1. USDA Forest Service, North Central Research Station, Hardwood Tree Improvement and Regeneration Center, West Lafayette, IN
47907-2061, USA / 2. Corresponding author (cmichler@fs.fed.us) / 3. Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN 47907-2061, USA / 4. USDA Forest Service, North Central Research Station, St. Paul, MN 55108, USA / Received October 29, 2004; accepted April 15, 2005; published online October 3, 2005
Summary
Approaches for the development of disease-resistant butternut (Juglans cinerea L.) are reviewed. Butternut is a threatened fine hardwood throughout its natural range in eastern North America because of
the invasion of the exotic fungus, Sirococcus clavigignenti-juglandacearum Nair, Kostichka and Kuntz, which causes butternut canker. Early efforts were made to identify and collect putatively resistant
germ plasm, identify vectors and to characterize the disease. More recently, molecular techniques have been employed to genetically
characterize both the pathogen and the resistant germ plasm. Much of the host resistance may originate from hybridization
with a close Asian relative, Japanese walnut (Juglans ailanthifolia Carr.), and from a few natural phenotypic variants. Further genetic characterization is needed before classical breeding
or genetic modification can be used to produce canker-resistant trees.
Keywords:
hybridization, polymorphism, regeneration, Sirococcus clavigignenti-juglandacearum, tree breeding, vegetative propagation.
