Teaching with basal fungal lineages
Letcher, Peter M. .
Zoospores of Chytridiomycota.
Autonomous, self-contained, and motile, all Chytridiomycota zoospores are created equal, in the sense that they all contain a basic assortment of organelles and structures that favor survival and reproductive success. It is simply the arrangement, and presence or absence of character states, of the organelles and structures that allow the systematist to discriminate among zoospore types. As a reproductive unit, the posteriorly uniflagellate zoospore carries the blueprints for the organismís next generation, as it either deliberately searches for, or serendipidously discovers, a suitable substrate from which to obtain nutrition necessary for germination and subsequent thallus development. At the light microscopy level, zoospore morphology has been applied as a taxonomic criterion over the last century. Thus, within Chytridiomycota, zoospores of Monoblepharidomycetes are oval or mouse-shaped and swim in a linear pattern, and in Chytridiomycetes, zoospores of Chytridiales, Rhizophydiales, Cladochytriales, and Lobulomycetales are generally spherical to oval and swim with a stop-and-start, darting motion, while zoospores of Spizellomycetales and Rhizophlyctidales may be globose, irregular, or elongate, and may or may not move in a darting pattern. Many ultrastructural features can be visualized with the use of stains. It is at the electron microscopy level that the concise distribution and arrangement of organelles, and the presence or absence of structures, becomes most apparent and more importantly, phylogenetically informative. Thus, chytrid systematics is currently based on specific zoospore ultrastructure combined with molecular monophyly, with one predicting the other. Constellations of ultrastructural features are used to delineate zoosporic fungi at all taxonomic levels from species to order. This presentation will demonstrate the use of light and electron microscopy of zoospores to discriminate among taxa in Chytridiomycota.
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1 - The University of Alabama, Biological Sciences, Box 870344, Tuscaloosa, AL, 35487, USA
Presentation Type: Symposium or Colloquium Presentation
Location: Cottonwood B/Snowbird Center
Date: Wednesday, July 29th, 2009
Time: 2:45 PM