Evolution of Filamentous Ascomycetes Inferred from LSU rDNA Sequence Data

Abstract

The nuclear LSU rRNA gene was examined in order to evaluate the current phylogeny of ascomycetes, which is mainly based on nuclear SSU rRNA data. Partial LSU rRNA gene sequences of 19 ascomycetes were determined and aligned with the corresponding sequences of 13 other ascomycetes retrieved from Genbank, including all classes traditionally distinguished and most of the recently accepted classes. The classification based on SSU rDNA data and morphological characters is supported, while the traditional classification and classifications based on the ascus type are rejected. Ascomycetes with perithecia and cleistothecia form monophyletic groups, while the discomycetes are a paraphyletic assemblage. The Pezizales are basal to all other filamentous ascomycetes. The monophyly of Loculoascomycetes is uncertain. The results of the LSU rDNA analysis agree with those of the SSU rDNA and RPB2 gene analyses, suggesting that most classes circumscribed in the filamentous ascomycetes are monophyletic. The branching order and relationships among these classes, however, cannot be elucidated with any of these data sets.

Abbreviations

LSU: large subunit

rDNA: ribosomal deoxyribonucleic acid

RPB2: gene coding for an RNA polymerase II subunit

rRNA: ribosomal ribonucleic acid

SSU: small subunit

Key words

Fungi - lichens - Ascomycotina - ribosomal DNA - molecular phylogeny - ascoma types

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Section Editor: H. M. Jahns