plant surface microbiology.pdf

4.2 Fusion-Interaction
16 Cellular Basidiomycete–Fungus Interactions 275
Typical fusion mycoparasites (Bauer and Oberwinkler 1990a, b) are the
Tremellales (including the Filobasidiales) of the Hymenomycetes (Bandoni
1984, 1995). Astonishingly, however, fusion mycoparasites are also scattered
throughout the Urediniomycetes. For example, the members of Cystobasidium,
Mycogloea, Naohidea, Occultifur, Spiculogloea and Zygogloea are fusion
mycoparasites (unpubl. data). Usually, basidiomycetous fusion mycoparasites
interact with their respective hosts by specialized interactive cells, designated
often as “tremelloid haustorial cells”. These cells were first described and designated
as “haustoria” by Olive (1947). Each tremelloid haustorial cell is subtended
by a clamp and consists of a subglobose basal part with one or more
thread-like filaments (e.g., see Oberwinkler et al. 1984) that are capable of fusing
with host cells via a pore of approximately 14–19 nm (Figs. 9, 10; Bauer
and Oberwinkler 1990a, b). Thus, a direct cytoplasm – cytoplasm connection
between the parasites and their respective hosts occurs.As discussed by Bauer
and Oberwinkler (1990a), the following stages in the development of the cel-
Fig. 9. Haustorial filament of Tetragoniomyces uliginosus (lower cell) in contact with a
host hypha (upper cell) demonstrating the fusion pore (arrowhead). Bar 0.5 µm