SYSTEMATIC BIOLOGY OF INVASIVE AND EMERGING PLANT PATHOGENIC FUNGI
Title: Leaf-inhabiting Genera of the Gnomoniaceae, Diaporthales
Submitted to: Studies in Mycology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 16, 2008
Publication Date: December 29, 2008
Citation: Sogonov, M.V., Castlebury, L.A., Rossman, A.Y., Mejia, L.C., White, J.F. 2008. Leaf-inhabiting Genera of the Gnomoniaceae, Diaporthales. Studies in Mycology. 62:1-79.
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. This research describes and illustrates a family of canker-causing fungi that belongs to the group of fungi that includes chestnut blight. Many of these species occur on hardwood trees 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 pathologists to determine the species of fungi that occur on hardwood trees.
The Gnomoniaceae are characterized by ascomata that are immersed, solitary, without a stroma or aggregated in a reduced, prosenchymatous stroma in herbaceous plant material, especially in leaves or stems, but also in wood. The ascomata are generally soft-textured, thin-walled, and prosenchymatous with either central or lateral beaks. Generally the asci have a distinct apical ring. This family includes species having ascospores that are generally small, less than 25 µm long, although some are longer especially species of Cryptosporella and range in septation from non-septate to one-septate, either median or eccentric, or multiseptate. The asexual states of members of the Gnomoniaceae are acervular or pycnidial with a broad opening, conidiogenous cells are phialidic, and conidia are pallid, non-septate. Molecular studies of the Gnomoniaceae suggest that the traditional concepts of genera based on characteristics of the ascomata in the substrata and position of the beak as well as ascospores such as shape and septation have resulted in genera that are not monophyletic. In this paper the concepts of the leaf-inhabiting genera in the Gnomoniaceae are reevaluated using multiple genes, specifically LSU nrDNA, ß-tubulin, tef1-a, and rpb2 for 102 gnomoniaceous species. Six genera of leaf-inhabiting genera are defined based on placement of the type species within the multigene phylogeny. The new monotypic genus Ambarignomonia is established for the unusual species, A. petiolorum. The phylogenetic affinities of unculturable species were determined by sequencing the ITS gene and analyzing that gene based on the newly defined generic concepts. A key to 54 species of leaf-inhabiting Gnomoniaceae is presented. Twenty two species in the type genus Gnomonia as well as Ambarignomonia, Apiognomonia, Gnomoniopsis and Ophiognomonia are described and illustrated.