Phylogenetic relationships and generic affinity of Uncinula septata inferred from nuclear rDNA sequences

Abstract

Based on 18S, 5.8S, and 28S rDNA sequences, the phylogenetic position of Uncinula septata within the Erysiphales has been inferred. Although appendages of the ascomata are uncinula like, i.e., unbranched with curvedcoiled apices, U. septata is situated at the very base of the large Erysiphales cluster, far away from the "pseudoidium clade" (Erysiphe emend., including Microsphaera and Uncinula). Morphologically, U. septata differs from the species of Erysiphe sect. Uncinula (ϵUncinula) in having terminal, pluriseptate ascoma appendages, curved ascospores, and the absense of an anamorph. This species is a basal, tree-inhabiting powdery mildew with some additional ancestral characteristics, viz., uncinula-like appendages and 8-spored asci. The new genus Parauncinula with U. septata as the type species is proposed. Uncinula curvispora (ϵU. septata var. curvispora) is tentatively maintained as a separate species, which is also assigned to Parauncinula.

Gene erosion and genome expansion in a group of highly host-specialized fungal phytopathogens

“…To validate further the correct placement of this species as an early-diverged PM but also to corroborate the PM-related content of the high confidence contigs, we proceeded with generating a multi-type locus phylogeny based on 1964 single-copy orthologs of 16 sequenced Leotiomycetes ( Figure 1D). The placement of the species by this approach at the base of the PM clade is in accordance with previous results based on ribosomal DNA (rDNA) sequences (Takamatsu, Limkaisang et al 2005).…”

“…The compact P. polyspora genome lacks large-scale compartmentalization and is indicative of homothallism. Parauncinula polyspora is believed to be an obligate biotroph that relies on living plant tissues for growth and reproduction (Takamatsu, Limkaisang et al 2005), and in vitro cultures on artificial media of the species have never been reported. Therefore, we resorted in sampling infected Q. serrata leaves assumed to represent largely P. polyspora mycelium and ascomata (fruiting bodies), and sequenced the respective epiphytic metagenome.…”

“…Here we present the genome of the PM species Parauncinula polyspora, pathogen of the East Asian oak tree Quercus serrata. It has been estimated that species of the genus Parauncinula have diverged from other genera of the Erysiphales 80-90 million years ago, rendering it one of the earliest diverged PM genera known to date (Takamatsu, Limkaisang et al 2005;Takamatsu, Ninomi et al 2005). The four species of Parauncinula (P. curvispora, P. polyspora, P. septata and P. uncinata) differ from other PMs in their unique morphology, host range, and also by lacking an asexual morph, i.e.…”

Myconet Volume 14. Part One. Outline of Ascomycota—2009. Part Two. Notes on Ascomycete Systematics. Nos. 4751–5113

“…Parauncinula S. Takamatsu,U. Braun & S. Limkaisang (4819) This new genus was proposed in Erysiphales with U. septata as the type species (Takamatsu et al, 2005). Uncinula curvispora was maintained as a separate species also assigned to this genus.…”

The current systematics and taxonomy of the powdery mildews (Erysiphales): an overview

“…Microidium (To-anun et al 2005) It has to be mentioned that the genera Caespitotheca (Takamatsu et al 2005b) and Parauncinula (Takamatsu et al 2005a), situated at the very base of the large Erysiphales clade, are not included in this classification. Also Brasiliomyces is not placed in the present system of tribes, because its phylogenetic position is not yet clear.…”