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Exploring the diversity of ascomycete fungi: Evolution of mating systems in Pleospora and discovery of new lineages in the dothideomycetes.

Patrik. Inderbitzin The University of British Columbia (Canada). 2005

Dissertation Abstracts International 66-02B.

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  • Title:
    Exploring the diversity of ascomycete fungi: Evolution of mating systems in Pleospora and discovery of new lineages in the dothideomycetes.
  • Author: Patrik. Inderbitzin
  • The University of British Columbia (Canada).
  • Subjects: Biology, Microbiology; Biology, Genetics
  • Is Part Of: Dissertation Abstracts International 66-02B.
  • Description: This thesis explored aspects of diversity in the ascomycete genus Pleospora and the new family Aliquandostipitaceae. In Pleospora, the main focus was on mating system evolution. I found that homothallism in Pleospora evolved in three different ways from heterothallism. One origin of homothallism resulted from a horizontal transfer across lineages involving a MAT locus.
    The approach chosen to investigate mating system evolution in Pleospora was based on delimiting the polyphyletic genus Pleospora to Pleospora sensu stricto, inferring a robust species phylogeny of Pleospora sensu stricto and cloning and examining the master regulator locus of sexual development in ascomycetes, the MAT locus. Conclusions were then drawn by integration of the total evidence.
    Research of mating system evolution in Pleospora was initiated by confirmation of the monophyly of Pleospora isolates with Stemphylium asexual states. This group contained the type of Pleospora, and was thus called Pleospora sensu stricto. Contributing towards a monophyletic genus Pleospora, the marine species P. gaudefroyi collected in British Columbia, and lacking a Stemphylium asexual state, was transferred to the new genus Decorospora. Phylogenetic 18S rDNA analyses and Shimodaira-Hasegawa and Kishino-Hasegawa tests rejected the null hypothesis of monophyly for the two taxa. Instead, Pleospora gaudefroyi grouped distantly from P. herbarum, at the base of the family Pleosporaceae confirming the importance of a Stemphylium asexual state for the definition of Pleospora sensu stricto in this case. Since no existing genus was available to accommodate P. gaudefroyi, the new genus Decorospora had to be erected.
    To generate a species phylogeny of Pleospora sensu stricto, 114 in-group taxa with Stemphylium asexual states were used. Phylogenetic analyses based on ITS, GPD, EF-1alpha and vmaA-vpsA DNA sequences with four different algorithms showed that Pleospora sensu stricto contained 22 phylogenetic species. Morphological species generally correlated well with phylogenetic species, except for the type P. herbarum whose phylogenetic species contained the four additional morphological species P. alfalfae, S. vesicarium, P. tomatonis and P. sedicola. (Abstract shortened by UMI.)
  • Publisher: Thesis (Ph.D.)--The University of British Columbia (Canada), 2005.
  • Creation Date: 2005
  • Format: 188 p..
  • Language: English
  • Identifier: ISBN9780612994836
  • Source: NUTN ALEPH
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