Evolution in Auriculariaceous Fungi: Structural and Molecular Approaches

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9306578 McLaughlin Evolutionary relationships within the basidiomycete fungi are not understood. These fungi can be divided into two groups based on the characteristics of the basidium. One of these groups, the heterobasidiomycetes, appears to be intermediate between the ascomycetes, the presumed ancestors of the basidiomycetes, and the presumably advanced second group. Research by Dr. McLaughlin will characterize ultrastructurally and cell biologically species in several orders of heterbasidiomycetes to elucidate their evolution and clarify their systematics. The characters to be examined include the spindle pole body, nuclear division, speta, the cytoskeleton, basidia, and branch initiation. Cladistic analysis of the structural characters will provide guidance on phylogenetic relationships. Phylogenetic trees obtained from analysis of molecular sequences of large subunit ribosomal DNA of the species examined structurally will be used to test conclusions reached with morphological data. %%% A major focus of this study will be the Auriculariales fungi. This unnatural order contains species with simple or complex septa. The simple septa moss parasites, which have been postulated to be ancestral to the rust fungi (Uredinales), will be intensively studied. In addition to the characters listed above, the cell interface between the moss host and the parasite will be examined, inoculation studies on mosses will be carried out,a nd asexual stages of the moss parasite will be characterized. In the complex septate Auriculariales cytological comparisons will be made with the Tremellales. To obtain material for this and future studied, fungi will be collected and cultured in Costa Rica.