Improving disease resistance of butternut (Juglans cinerea), a threatened fine hardwood: a case for single-tree selection through genetic improvement and deployment.
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.
Michler
Charles H
CH
USDA Forest Service, North Central Research Station, Hardwood Tree Improvement and Regeneration Center, West Lafayette, IN 47907-2061, USA. cmichler@fs.fed.us
Pijut
Paula M
PM
Jacobs
Douglass F
DF
Meilan
Richard
R
Woeste
Keith E
KE
Ostry
Michael E
ME
D005818:Genetic Engineering; D007113:Immunity, Innate / Q000235:genetics*; D031324:Juglans / Q000276:immunology*; D010935:Plant Diseases / Q000276:immunology*; D012641:Selection, Genetic