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Permanent link (DOI): https://doi.org/10.7939/R38Q1Z

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Diaspores and degradative abilities of select dematiaceous hyphomycetes Open Access

Descriptions

Other title
Subject/Keyword
Dematiaceous hyphomycetes
Degradation
Diaspores
Type of item
Thesis
Degree grantor
University of Alberta
Author or creator
Day, Melissa
Supervisor and department
Currah, Randolph (Biological Sciences)
Examining committee member and department
Blanchette, Robert (Plant Pathology, University of Minnesota)
Sigler, Lynne (Biological Sciences)
Foght, Julia (Biological Sciences)
Strelkov, Stephen (Agriculture, Food, and Nutritional Science)
Hall, Jocelyn (Biological Sciences)
Department
Department of Biological Sciences
Specialization

Date accepted
2010-09-29T22:35:31Z
Graduation date
2010-11
Degree
Doctor of Philosophy
Degree level
Doctoral
Abstract
Dematiaceous hyphomycetes are a taxonomically diverse artificial assemblage of conidial fungi that have dark pigments known as melanins in their walls. Select dematiaceous hyphomycetes from the Coniochaetales, Pleosporales, and Helotiales obtained from arctic and alpine bryophytes and vascular plant roots were chosen for further study. Eight isolates, all from roots of Saxifraga oppositifolia, represented a new species of Monodictys, M. arctica. This species, characterised by large, darkly pigmented, multicelled, often branching conidia, was most closely related to members of the Leptosphaeria, making M. arctica potentially the first non-pycnidial anamorph associated with that genus. In alpine glacial forefields, the primary colonisers are bryophytes, which form an organic grout between the rocks. These mosses trap organic particles. Three pleosporalean fungi were isolated from this grout and examined to see if they could degrade moss. All three removed the outer, cellulose rich layer of the cells, but not the inner, polyphenol rich layer. I propose that the mosses disarticulate after degradation and the fragments are trapped in the grout, increasing soil organic matter and aiding pedogenesis. This first soil ostensibly facilitates colonisation by vascular plants, the roots of which are colonised by dark septate endophytes (DSE), a group known for asymptomatically colonising vascular plant roots and thought to be quasi-mycorrhizal. Cadophora luteo-olivacea, Cadophora melinii, Leptodontidium orchidicola, Phialocephala fortinii and Coniochaeta nepalica were examined for their abilities to degrade moss. All showed that colonisation patterns varied along with the formation of conidia and sclerotic structures, which could serve as inocula for establishing species of vascular plants. Cadophora and Phialocephala are delineated by phialide complexity, so I decided traced the origin and evolutionary history of that character on a phylogenetic framework. Based on this reconstruction, phialide complexity is a good character for separating the two genera. I propose that the sclerotium of the outgroup taxon, which develops phialides that produce spermatia, evolved into the phialidic heads of Phialocephala, which resemble sclerotia, and then into the solitary phialides of Cadophora. Traits in the sexual fungi associated with these asexual taxa support the phylogenetic placement of the asexual fungi.
Language
English
DOI
doi:10.7939/R38Q1Z
Rights
Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.
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