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2013 APS Annual Meeting Abstract


Oral Technical Session: Fungal Ecology 2


A multigene phylogeny of Chytridiales (Chytridiomycetes).
S. SEKIMOTO (1), P. M. Letcher (1), J. E. Longcore (2), M. J. Powell (1)
(1) The University of Alabama, Tuscaloosa, AL, U.S.A.; (2) The University of Maine, Orono, ME, U.S.A.

Chytridiales is one of the larger orders in the fungal phylum Chytridiomycota. Members of the order are common in aquatic habitats and are associated with freshwater algae, insect exuviae and cellulosic substrates. They are morphologically diverse, most with monocentric thalli but a polycentric genus is also present. Inoperculate and operculate sporangia are represented. Phylogenetic hypotheses based primarily on ribosomal RNA (SSU and LSU) genes have left the branching order of deep nodes of the tree poorly understood with at least 16 sub-clades. Some of these sub-clades then formed two well-supported larger clades, recognized as the families Chytridiaceae and Chytriomycetaceae. Greater taxon sampling and inclusion of protein-coding genes are believed to increase resolution of backbone phylogenies. To increase understanding of the order Chytridiales, we included a wide range of isolates and sequenced five genes (EF1, EF2, RPB1, SSU and LSU). The resulting phylogeny had basically the same tree topology as the rRNA gene tree and bootstrap support values did not significantly improve. Analysis including protein-coding genes, however, was effective in resolving some problematic lineages with long branches in the rRNA gene tree. This result differed from our preliminary multigene analyses of other chytrid orders and might indicate different evolutionary processes in Chytridiales compared to other chytrid orders.

2013 by The American Phytopathological Society. All rights reserved.