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United States Department of Agriculture

Agricultural Research Service

Research Project: Systematics and Diagnostics of Emerging and Quarantine-Significant Plant Pathogenic Fungi

Location: Systematic Mycology and Microbiology

Title: Valsalnicola D. Walker & Rossman, gen. nov.

Authors
item Walker, Donald
item Vacant, Rl,
item Adams, Gerard
item Longa, Claudia
item Maresi, Giorgio

Submitted to: Persoonia: Molecular Phylogeny and Evolution of Fungi
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 4, 2012
Publication Date: December 29, 2012
Citation: Walker, D.M., Rossman, A.Y., Adams, G.C., Longa, C.M., Maresi, G. 2012. Valsalnicola D. Walker & Rossman, gen. nov. Persoonia: Molecular Phylogeny and Evolution of Fungi. 29:148-149.

Interpretive Summary: Fungi cause serious diseases of agricultural and forest crops. One fungus related to the chestnut blight family causes decline of green alder in Alaska and at high elevations in Europe. Because of its superficial resemblance to another fungus, it has often been confused with a harmless fungus that occurs on the same host. Distinguishing these two fungi is essential for controlling this disease of alder. In this paper the disease-causing fungus was studied using microscopic structures and molecular sequences. It was determined that this fungus should have a different name in order to distinguish it from the look-a-like non-pathogen. This research will be used by forest pathologists to distinguish these species of fungi on alder.

Technical Abstract: Valsonectria is based on a species that was described in the genus Valsa. Although it resembles Valsa in having allantoid ascospores, the ascospores of Valsalnicola are one-septate while the majority of species of Valsa and the closely related Leucostoma and Valsella have non-septate ascospores. However, one species of Valsa, V. melanodiscus, also has one-septate ascospores, occurrence on Alnus spp., and produces linear cankers on the host. This similarity causes problems in differentiating the two fungi particularly because the septum in V. melanodiscus lacks clear delineation in some mounting solutions. Distinguishing features of Valsalnicola are the lack of a black line stromata in the ascomatal cavity characteristic of Valsa melanodiscus and other members of the Valsaceae. In addition the growth rate of Valsalnicola oxystoma is considerably slower than species of Valsa. Molecular sequence data place this new genus within the Gnomoniaceae-Melanconidaceae complex. Allantoid, one-septate ascospores have not previously been reported in the Melanconidiaceae or Gnomoniaceae. Comparison of ITS sequences of specimens from Alaska and Italy were identical. The basionym has been cited as the Rehm: Ascomyceten 270 (1875) in Index Fungorum reflecting an error in Saccardo (1882) but the correct number is Rehm: Ascomyceten 280, which does not include a description.

Last Modified: 10/31/2014
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