Teaching with basal fungal lineages
Simmons, D. Rabern .
Chytridiomycota: Thallus development.
Until the reliance upon zoosporic ultrastructure and, more recently, molecular sequences, thallus development on naturally-occurring substrates was the basis of chytrid taxonomy. Major groupings within the Chytridiales sensu Sparrow were defined by development of the posteriorly-flagellated zoospore into a propagule-releasing zoosporangium. The zoospore of a holocarpic chytrid gives rise to a new thallus composed solely of a zoosporangium within a host substrate. A eucarpic chytrid, however, produces securing and absorptive rhizoids branching from one or more sites off of the zoosporangium. Eucarpic chytrids may produce a single zoosporangium (monocentric development) or multiple zoosporangia throughout a vegetative rhizomycelium (polycentric development). Growth patterns of monocentric chytrids can be further divided based on the growth of the zoosporangium by the enlargement of the initial encysted zoospore (endogenous growth) or an enlargement of an extension from the cyst (exogenous growth). Pure cultures of some chytrid species can be easily grown in the lab to teach these modes of development. Phylogenies based on cellular and molecular composition of chytrids indicate that these types of development have evolved within multiple lineages. Therefore, chytrids from phylogenetically distinct groups can have very similar thallus morphologies. These features, however, are practically informative and remain vital for generic or specific descriptions.
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1 - University of Maine, School of Biology and Ecology, 5722 Deering Hall, Orono, Maine, 04469-5722, United States of America
Presentation Type: Symposium or Colloquium Presentation
Location: Cottonwood B/Snowbird Center
Date: Wednesday, July 29th, 2009
Time: 2:15 PM