Submitted to: Mycologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/8/2010
Publication Date: 10/14/2010
Citation: Walker, D., Castlebury, L.A., Rossman, A.Y., Sogonov, M., White, J. 2010. Systematics of the genus Gnomoniopsis (Gnomoniaceae, Diaporthales) based on a three gene phylogeny, host associations, and morphology. Mycologia. 102:1479-1496. Interpretive Summary: Fungi are a group of organisms that cause billions of dollars damage each year to agricultural and forest resources in the United States. One group of fungi includes the species that caused chestnut blight in the eastern United States killing all of the chestnut trees. Many additional fungi belong to the same group and cause diseases of forest trees and crop plants. This research describes and illustrates all fungal species in a genus related to the chestnut blight fungus. Many of these species occur on hardwood trees and herbaceous plants in North America, although most of them do not cause serious diseases. This research provides descriptions and illustrations of these fungi along with a key for identification. In addition, relationships between these species have been determined based on DNA sequences. This paper will be used by forest and plant pathologists to determine the species of fungi that occur on hardwood trees and crops.
Technical Abstract: The species of Gnomoniopsis are leaf- and stem-inhabiting pyrenomycetes that infect plants in the Fagaceae, Onagraceae, and Rosaceae. The monophyly and species level relationships among thirteen species of Gnomoniopsis (Gnomoniaceae, Diaporthales) were assessed using morphological, cultural, and molecular analyses. DNA sequences were utilized from three genes: ß-tubulin, ITS1, 5.8S rDNA, and ITS2 regions, and translation elongation factor 1a (tef-1a). Secondary structural alignment of the ITS region across four genera in the Gnomoniaceae increased the ability to determine homologous positions in the ITS alignment. This study agrees with a recent proposed concept of Gnomoniopsis and offers phylogenetic resolution of additional species. Fresh specimens were collected, isolated into culture, and subjected to phylogenetic analysis. Type specimens were compared with newly obtained isolates to determine their identity. Four new combinations and one new species are proposed. This paper includes descriptions and illustrations of these five species and four previously described species of Gnomoniopsis. A key is provided to the 13 species of Gnomoniopsis.