My current research focuses on events in recognition and attachment of motile spores of protista and fungi to hosts and substrates. Electron microscopic studies have revealed that special vesicles carry cellular glues which are released when motile spores are stimulated to encyst. The questions being asked are how universal is this mechanism of attachment. Some organisms involve flagella in adhesion, and other flagellated cells do not. Do adhesion vesicles and flagella have complementary roles? How has the adhesion process evolved among these organisms? How can this information reveal new understandings of systematic relationships among protista and fungi? These investigations use light, fluorescence and electron microscopy. Systematic analysis of microscopic and developmental characters includes phenotypic and cladistic techniques.
A second area of research focuses on the ecological roles of a group of under-recognized
flagellated fungi, the Chytridiomycetes. Students in my laboratory are exploring
associations of Chytridiomycetes with other organisms to determine what factors
influence species diversity and distribution. Emphasis is placed on developing
techniques which adequately reveal which organisms are present. Powell, M.J.
and W.H. Blackwell. 1998. Phenetic analysis of genera of the Saprolegniaceae
(Oomycetes). Mycotaxon 68: 505-516.
Selected publications
Bills, G., M. Christensen, M. Powell, and G. Thorn. 2004. Saprobic soil fungi. In: Biodiversity of fungi: Inventory and monitoring methods (G.M. Mueller, G. Bills, and M.S. Foster, Eds.). Elsevier. Pgs. 271-302.
Blackwell, W.H., P.M. Letcher, and M.J. Powell. 2004. Synopsis and systematic reconsideration of Karlingiomyces (Chytridiomycota). Mycotaxon 89: 259-276.
Letcher, P., P.A. McGee and M.J. Powell. 2004. Zoosporic fungi from soils of New South Wales. Australasian Mycologist 22: 99-115.
Letcher, P.J., P.A. McGee, and M.J. Powell. 2004 Diversity of chytrids from soils of four vegetation types in New South Wales Australia. Can. J. Bot. 82: 1490-1500.
Letcher, P.M., M.J. Powell, J.G. Chambers, and W.H. Holznagel. 2004. Phylogenetic relationships among Rhizophydium isolates from North America and Australia. Mycologia 96: 1363-1375.
Letcher, P.M. and M.J. Powell. 2005.Kappamyces, a new genus in the Chytridales (Chytridiomycota). Nova Hedwigia 80: 115-133.
Letcher, P.M. and M.J. Powell. 2005.Phylogenetic position of Phlyctochytrium planicorne (Chytridiales, Chytridiomyctoa) based on zoospore ultastructure and nuclear LSU sequence analysis. Nova Hedwigia 80: 135-146.
In Press
Letcher, P.M., M.J. Powell, J.G. Chambers, J.E. Longcore, P.F. Churchill,
and P.M. Harris. Ultrastructural and molecular delineation of the Chytridiaceae
(Chytridiales). Can. J. Bot.