Martha Powell

Martha J. Powell

Professor Emeritus


My research focuses on the biology of zoosporic fungi, especially Chytridiomycota.
In our research we use cell biological, microscopic, molecular, ecological and systematic approaches to understand relationships of these organisms, how their zoospores function, and what their roles are in the environment. A central focus to all of this research is the discovery and description of new organisms.

We explore answers to a range of questions. How does adaptation to soil versus aquatic habitats drive speciation? What are the mechanisms zoospores use to detect and respond to environmental clues, including light and nutrition? What are the cellular processes involved in the attachment of motile spores to hosts and substrates once suitable substrates are detected? How have these process evolved among these organisms? How can this information reveal new understandings of systematic relationships among protista and fungi? How can we detect the distribution of Chytridiomycota in the environment?

Selected Publications


  • Blackwell, W.H., P.M. Letcher, M.J. Powell, C.G. Vélez. 2011. The occurrence of Blyttiomyces spinulosus in Alabama and Argentina, and comments on the genus Blyttiomyces (Chytridiomycota).   Phytologia 93(3): 304-315.
  • Powell, M.J., P.M. Letcher, and J.E. Longcore. 2011. Operculomyces is a new genus in the order Rhizophydiales. Mycologia 103:854-862.
  • Vélez, C.G., P.M. Letcher, S. Schultz, M.J. Powell, P.F. Churchill. 2011. Molecular phylogenetic and zoospore ultrastructural analyses of Chytridum olla establish the limits of a monophyletic Chytridales. Mycologia 103: 118-130.


  • Blackwell, W.H., P.M. Letcher, and M.J. Powell 2012. Synopsis of Obelidium (Chytridiomycota) Phytologia 94 (1): 103-117.
  • Lefevre, E., P.M. Letcher., and M. J. Powell. 2012. Temporal variation of the small eukaryotic community in two freshwater lakes: Emphasis on the zoosporic fungal community. Aquatic Microbial Ecology  67: 91-105.
  • Letcher, P.M. and M.J. Powell. 2012. A taxonomic summary and revision of Rhizophydium (Rhizophydiales, Chytridiomycota). Zoosporic Research Institute. No. 1. Imprint Tuscaloosa, AL: University Printing, The University of Alabama. 216 pgs. ISBN: 978-0-615-66279-4.
  • Letcher, P.M., M.J. Powell, and K. Picard. 2012. Zoospore ultrastructure and phylogenetic position of Phlyctochytrium aureliae Ajello is revealed (Chytridiaceae, Chytridiales, Chytridiomycota). Mycologia 104: 410-418.
  • Letcher, P.M., C.G. Vélez, S. Schultz, and M.J. Powell. 2012. New taxa are delineated in Alphamycetaceae (Rhizophydiales, Chytridiomycota). Nova Hedwigia: 94: 6-29.
  • Powell, M.J. and P.M. Letcher. 2012. From Zoospores to Molecules: The evolution and systematics of Chytridiomycota. In: Systematics and Evolution of Fungi: Morphological and Molecular Approaches ( J.K. Misra, J.P. Tewari and S.K. Deshmukh.) pgs. 29-54. ISBN 978-1-57808-723-5
  • Simmons, D.R., P.M. Letcher, M.J. Powell, and J.E. Longcore. 2012. Alogomyces tanneri gen. et sp. nov., a chytrid in Lobulomycetales from horse manure. Mycologia 104: 157-163.


  • Blackwell, W.J., P.M. Letcher, and M.J. Powell 2013. An Oomycete parasitizing algae occurring on dorsal shells of turtles. Phytologia 95: 34-41.
  • Davis WJ, Letcher PM, Powell MJ. 2013. Chytrid diversity of Tuscaloosa County, Alabama. Southeastern Naturalist 12: 666-683.
  • Letcher, P.M., S. Lopez, R. Schmieder, P.A. Lee, C. Behnke, M. J. Powell, and R.C. McBride. 2013.
    Characterization of Amoeboaphelidium protococcarum, an algal parasite new to the Cryptomycota isolated from an outdoor algae pond used for the production of biofuel. PLoS ONE 8(2): e56232.
  • Picard, K.P., P.M. Letcher, and M.J. Powell. 2013.  Evidence for a facultative mutualist nutritional relationship between the green coccoid alga Bracteacoccus sp. (Chlorophyceae) and the zoosporic fungus Rhizidium phycophilum (Chytridiomycota). Fungal Biology 117: 319-328.
  • Powell, M.J., P.M. Letcher, and J.E. Longcore. 2013. Pseudorhizidium is a new genus with distinct zoospore ultrastructure in the order Chytridiales. Mycologia 105 (2): 496-507.
  • Vélez, C.G., P.M. Letcher, S. Schultz, G. Mataloni, E. Lefèvre, and M.J. Powell. 2013. Three new genera in Chytridales from aquatic habitats in Argentina. Mycologia 105: 1251-1265.


  • Akinowole PO, Lefevre E, Powell MJ, Findlay RH. 2014. Unique odd-chain polyenoic phospholipid fatty acids present in chytrid fungi. Lipids 49: 933-942.
  • Blackwell, W.H., P.M. Letcher and M.J. Powell. 2014. Questions regarding genus Myzocytium (Oomycota, Straminipila) and its species: Variation and identity of specimens in west-central Alabama. Phytologia 96(2): 41-46.
  • Letcher, P.M. and M. J. Powell. 2014. Hypothesized evolutionary trends in zoospore ultrastructural characters in Chytridiales Mycologia 106: 379-396.
  • Letcher, P.M., J.E. Longcore, and M.J. Powell. 2014. Dendrochytridium crassum, a new genus in Chytridiales with unique zoospore ultrastructure. Mycologia 106:145-153.
  • Letcher, P.M., J.E. Longcore, and M.J. Powell. 2014. Irineochytrium, a new genus in Chytridiales having zoospores and aplanospores. Mycologia 106: 1188-1198.
  • Powell, M.J. and P.M. Letcher. 2014. Chytridiomycota, Monoblepharidomycota, and Neocallimastigomycota. In: The Mycota Systematics and Evolution, 2nd Edition. VII Part A.
    (D. McLaughlin and J.W. Spatafora, eds) Springer pp 141-175.
  • Powell, M.J. and P.M. Letcher. 2014. Phylogeny and characterization of freshwater Chytridiomycota (Chytridiomycetes and Monoblepharidomycetes). In Freshwater Fungi and Fungus-Like Organisms (Gareth Jones, Ka-Lai Pang, and Kevin D. Hyde, eds) De  Gruyter pp 133-153.
  • Robbertse B, Schoch CL, Robert V,…Letcher PM, Powell MJ et al. 2014.  Finding needles in haystacks: linking scientific names, reference specimens and molecular data for Fungi. Database (on-line)


  • Blackwell WH, Letcher PM, Powell MJ. 2015.  A review and update of the genus Sapromyces (Straminipila: Oomycota). Phytologia 97: 82-93.
  • Davis WJ, Letcher PM, Longcore JE, Powell, MJ.  2015. Fayochytriomyces is a new genus within Chytridiales. Mycologia 107 (2): 432-439.
  • Letcher PM, Powell MJ, Lopez S, Lee PA, McBride RC. 2015. Amoeboaphelidium protococcarum, and Amoeboaphelidium occidentale, a new species in phylum  Aphelida (Opisthosporidia). Mycologia 107: 522-531.
  • Letcher PM, Powell MJ, Davis WJ. 2015. A new family and four new genera in Rhizophydiales (Chytridiomycota). Mycologia 107: 808-830.
  • Powell, MJ, Letcher PM, Chambers JG, Roychoudhury S. 2015. A new genus and family for the misclassified chytrid, Rhizophlyctis harderi. Mycologia 107:419-431.


  • Blackwell WH, Letcher PM, Powell MJ. 2016. Reconsideration of the inclusiveness of genus Plasmophagus (Chytridiomycota, posteris traditus) based on morphology. Phytologia 98(2): 128-136.
  • Davis WJ, Antonetti J, Letcher PM, Powell MJ. 2016. Phylogenetic diversity of Chytridiomycetes in a temporary forest pond surveyed using culture-based methods. Southeastern Naturalist 15: 534-548.
  • Davis WJ, Letcher PM, Powell MJ.2016. Borealophlyctis nickersonii, a new species in Rhizophlyctidales. Mycologia  108: 744-752.
  • Davis WJ, Letcher PM, Powell MJ. 2016. Triparticalcar sp. nov., a new coprophilous species within Spizellomycetales, Chytridiomycota. Phytologia 98: 241-249.
  • Leshem T, Letcher PM, Powell MJ, Sukenik A. 2016.  Characterization of a new chytrid species parasitic on the dinoflagellate, Peridinium gatunense. Mycologia 108: 731-743.
  • Letcher PM, Lee PA, Lopez S, Burnett M, McBride RC, Powell MJ. 2016. An ultrastructural study of Paraphysoderma sedebokerense (Blastocladiomycota), an epibiotic parasite of microalgae. Fungal Biology 120: 324-337.
  • Powell, M. J. 2016.  Chytridiomycota. In: Handbook of the Protists (J.M. Archibald, A. Simpson, C.H. Slamovits, eds.) Springer. DOI 10.1007/978-3-319-32669-6_18-1
  • Powell, M. J. 2016. Blastocladiomycota. In: Handbook of the Protists (J.M. Archibald, A. Simpson, C.H. Slamovits, eds.) Springer. DOI 10.1007/978-3-319-32669_17-1


  • Blackwell WH, Letcher PM, Powell MJ. 2017. The taxa of Dictyomorpha (Chytridiomycota, in praesens tempus). Phytologia 99: 75-83.
  • Letcher PM, Longcore JE, Quandt CA, Leite DS, James TY, Powell MJ. 2017. Morphological, molecular, and ultrastructural characterization of Rozella rhizoclosmatii, a new species in Cryptomycota. Fungal Biology Fungal Biology 121: 1-10.
  • Letcher PM, Longcore JE, James TY, Leite DS, Simmons DR, Powell MJ. 2017. Morphology, ultrastructure, and molecular phylogeny of Rozella multimorpha, a new species in Cryptomycota. Eukarotic Microbiology. doi:10.1111/jeu.12452   on line 27 July 2017.
  • Letcher PM, Powell MJ, Lee PA, Lopez S, Burnett M. 2017. Molecular phylogeny and ultrastructure of Aphelidium desmodesmi, a new species in Aphelida (Opisthosporidia). Eukaryotic Microbiology 2017. 1-13. doi: 10.1111/jeu.12401.
  • Powell MJ, Letcher PM, James TY. 2017. Ultrastructural characterization of the host –parasite interface between Allomyces anomalus (Blastoclaidomycota) and Rozella allomycis (Cryptomycota). Fungal Biology 121:561-572. doi:10.1016/j.funbio.2017.03.002.