|Sheer Hyten, Aimee|
Submitted to: Canadian Journal of Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/7/2006
Publication Date: 10/17/2006
Citation: Castlebury, L.A., Rossman, A.Y., Sheer Hyten, A.M. 2006. Phylogenetic Relationships of Neonectria/Cylindrocarpon on Fagus in North America. Canadian Journal of Botany. 84:1417-1433. Interpretive Summary: Beech bark canker has been known in North America since the late 1800’s but recently this disease has spread westward as far as Michigan and southward to Tennessee. For about thirty years it has been known that two different species of fungi are involved in beech bark canker but the distinction between them is not clear. In this research the fungi that cause beech bark canker are differentiated based on their microscopic characteristics as well as a comparison of their genes. It was determined that one fungal species on beech causes cankers only on that host tree in North America. A second fungal species attacks a wide range of trees including beech, birch, maple, and tulip poplar in both North America and Europe. A third species is known only on beech in Europe. This research will be used by forest pathologists who are breeding for beech trees that are resistant to beech bark canker and other diseases of hardwood trees. In addition it will be used by plant quarantine officials to prevent the introduction of these disease-causing fungi from Europe to North America and vice versa.
Technical Abstract: The relationship of two species of Neonectria associated with beech bark canker in North America was evaluated by comparing isolates of these and additional species on Fagus in the Neonectria coccinea group. Gene regions in the translation elongation factor 1-alpha (EF1-'), RNA polymerase II second largest subunit (RPB2), and '-tubulin were sequenced and analyzed. Molecular data suggest that the fungus associated with beech bark disease previously known as Neonectria coccinea var. faginata (' Nectria coccinea var faginata) should be recognized as its own species, Neonectria faginata, distinct from Neonectria coccinea. Neonectria faginata is known only from North America on Fagus. A second species associated with beech bark disease is Neonectria ditissima, which can be distinguished morphologically from N. faginata based on ascospore size, conidial size and shape, and colony pigmentation. Neonectria distissima includes isolates referred to as Neonectria galligena and occurs on a variety of hardwood trees in North America and Europe. Neonectria coccinea is determined to occur only on Fagus in Europe. Neonectria major is recognized for a species that occurs only on Alnus in Canada (British Columbia), France, Norway, and United States (Washington). The following nomenclatural changes are made: Neonectria faginata comb. & stat. nov., Neonectria fuckeliana comb. nov., Neonectria hederae comb. nov., Neonectria major comb & stat. nov. and Neonectria punicea comb. nov.