Submitted to: Mycotaxon
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 8, 2010
Publication Date: April 25, 2011
Citation: Minnis, A., Rossman, A.Y., Olsen, R.T. 2011. Mycosphaerella nyssicola revisited: characterization of a species distinct from M. punctiformis. Mycotaxon. 155:311-322.
Interpretive Summary: Swamp tupelo or black gum trees are valuable ornamental plants that are affected by a serious leaf spot disease. Plant breeders have been unable to develop trees resistant to this disease because of lack of knowledge about its cause. Initially a fungus with a broad host range was considered to cause the disease. With much effort the causal fungus was obtained in culture and accurately identified using microscopic characters and DNA sequencing. The pathogen was determined to be a fungus that only infects tupelo trees. This research will be used by tree pathologists in order to breed ornamental trees that are resistant to this leaf disease.
Nyssa trees involved in a breeding program for ornamentals were found to be affected deleteriously by a leaf spot disease. The causative agent was identified as a species of Mycosphaerella that had been classified as morphologically indistinguishable from and likely M. punctiformis. A subsequent taxonomic investigation using morphological data of new and existing herbarium collections, cultural data, and ITS region rDNA sequences suggested that this was a distinct species on Nyssa that is correctly named M. nyssicola. Typifications of this species are performed to promote nomenclatural and taxonomic stability.