most studied species of the Tremellomycetes
a haustorial filament forms only one fusion
channel (Fig.12.6a, b), inSyzygospora pallida
a single haustorial filament may form several
protrusions into the host cytoplasm, resulting
in numerous fusion channels per filament
(Fig.12.6c, d) (Bauer 2004 ; Bauer and Ober-
winkler1990b; Oberwinkler et al. 1984 ).
III. Life Cycles
A. Dimorphism
Dimorphism, i.e., differing morphological
organization of different life stages, is a
characteristic trait in most species of the Tre-
mellomycetes for which a teleomorph is
known. A typical life cycle of aTremellaspe-
cies is illustrated in Fig.12.4. In these species,
basidiospores germinate by budding to estab-
lish ahaploid yeast stage.Sincethisstagecan
easily be maintained in pure culture on stan-
dard media, it is assumed that the yeast stage is
saprotrophic.
Conjugation of compatible yeast cells
initiates a dikaryotic hyphal stage, which is
considered mycoparasitic in many species
based on two lines of evidence. First, axenic
cultivation of this stage has seldom been
reported (Zugmaier and Oberwinkler 1995 ;
Zugmaier et al. 1994 ). Second, tremelloid
haustoria attached to hyphae of other fungal
species are often observed microscopicallyFig. 12.5Septal pore architecture in Tremellomycetes.
Bar¼0.1mmin(a–c), 0.2mmin(d). (a) Dolipore of
Cystofilobasidium ferigulawithout specialized multila-
mellate caps, representative of Cystofilobasidiales. Note
that pore is surrounded at each side by a more or less
dome-shaped ER cisterna. (b–d) Dolipores surrounded
at each side by many multilamellate cupulate cap ele-
ments, representative of Tremellomycetes [except for
Cystofilobasidiales; see (a)] andWallemia.(b,c)Tre-
mellasp. Cupulate cap elements are sectioned longitu-
dinally in (b), transversally in (c). Continuity between
ER and saccules is visible for one of upper saccules in
(b). (d)Wallemia sebi(a) reprinted from Sampaio et al.
( 2001 ) with permission338 M. Weiss et al.