Submitted to: Mycological International Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: August 12, 2002
Publication Date: N/A
Technical Abstract: Mycosphaerella is one of the largest groups of plant pathogenic fungi with more than 1800 species names. Anamorphs associated with Mycosphaerella number more than 40, many of which also are economically important with large numbers of species. For example, Cercospora and Septoria contain more than 3000 and 1000 species names, respectively, most of which probably were derived from species with a Mycosphaerella teleomorph. Despite their common occurrence and high economic importance, members of this genus have been under-represented in phylogenetic analyses and the taxonomic position of Mycosphaerella is uncertain. Most taxonomists place the genus in the order Dothideales. However, this conclusion has not been supported by limited analyses of 18S ribosomal RNA gene sequences. To test whether the genus Mycosphaerella belongs in the order Dothideales, 18S rDNA sequences were obtained from five species representing the major groups within the genus identified in previous analyses of ITS sequences. All five species of Mycosphaerella clustered together but separate from species of Dothidea and formed a basal group to the other loculoascomycetes in a neighbor-joining analysis of 109 18S sequences. Species of Dothidea clustered with those of Botryosphaeria, another genus of uncertain taxonomic position. Inclusion of Mycosphaerella within the Dothideales was not supported by this analysis and a new order may be needed to accommodate species of Mycosphaerella and related genera.