Book of Abstracts (PDF) - International Mycological Association

IMC7 Main Congress Theme V: CELL BIOLOGY AND PHYSIOLOGY Posters
1173 - Correlation of parasitism and gradual selectivity
between lichen bionts - molecular data and culture
experiments verify morphological observations
T. Schaper 1 , A. Beck 2 & S. Ott 1*
1 Botanical Institute, University of Duesseldorf,
Universitätsstr. 1, D-40225 Duesseldorf, Germany. -
2 Department Biologie I, Bereich Biodiversitätsforschung,
L.-M.-Universität Muenchen, Menzinger Str. 67, D-80638
Muenchen, Germany. - E-mail: otts@uni-duesseldorf.de
The mutualistic interactions between lichen species range
from different steps of symbiosis to parasitism. Intra- and
interspecific interactions characterise the lichen species
within the close association on the gravel alvar of Gotland,
Sweden. Concerning these complex interactions the degree
of selectivity of the lichen bionts is of great importance.
For lichens only reproducing sexually the availability of
the suitable photobiont is a crucial prerequisite for
relichenisation. The ITS rDNA sequences of the
photobionts demonstrate the diversity of the photobiontal
pool within the lichen community. Different species of
Trebouxia belonging to Clade I which is divided in two
subgroups as well as species of the genus Asterochloris has
been found. The molecular data verify and support the
morphological observations of the parasitic contact
between Fulgensia bracteata and Toninia sedifolia. Both
lichens share the same photobiont. In culture experiments
with the isolated photobionts of five lichen species in
combination with the mycobiont of F. bracteata gradual
stages of the first steps of the relichenisation process get
obvious. These observations indicate to a reduced
selectivity of the mycobiont of F. bracteata in its
photobiontal choice. The mycobiont of F. bracteata forms
a temporary aggregate with different ? maybe less -
compatible bionts. This enables the mycobiont to survive
until the association with a compatible photobiont is
established and thallus formation is initiated.
1174 - Mating reactions, sexual morphogenesis, and
trisporic acid in zygomycetes
C. Schimek * , K. Kleppe, A.R. Saleem, A. Petzold & J.
Wöstemeyer
Friedrich-Schiller Universität, Institute of General
Microbiology and Microbial Genetics, Neugasse 24, D-
07743 Jena, Germany. - E-mail: B9SCCR@nds.rz.unijena.de
It is understood that mating reactions in zygomycetes are
mediated by trisporic acid. But this generalization was only
valid for mucoralean fungi, as no other orders had been
examined in that respect. We present data on several
species of the order Mortierellales covering physiological,
biochemical, and molecular biological approaches. We
found that in Mortierellales, too, the sexual responses are
mediated by trisporoids. So in zygomycetes, the same
signalling system is used not only beyond family limits but
also crossing order barriers, a feature unique in fungi.
Trisporoids are derivatives of beta-carotene that are
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Book of Abstracts
synthesized in a cooperative process by the different
mating types. Some trisporoids act as pheromones, others
show hormone-like activities. Although specific trisporoid
isoform patterns are typical for certain species,
interspecific reactions occur quite frequently and we have
also observed inter-order reactions. Interspecific reactions
are especially interesting in parasitism. A few species, e.g.
Parasitella parasitica are parasites to other zygomycetes in
a mating type-dependent manner: interactions occur only if
the partners belong to opposing mating types. The
susceptibility to parasitism by Parasitella can therefore be
used as a marker for studying the relationship between
species. Using in-situ techniques, the involvement of the
same key enzymes for trisporoid metabolism could be
shown in sexual as well as in parasitical interactions.
1175 - Regulation of sex-pheromone biosynthesis and its
role in mating and parasitic interactions of mucoralean
fungi
K. Schultze, J. Wöstemeyer & A. Burmester *
Friedrich-Schiller-University Jena,Institute of
Microbiology, Neugasse 24, D-07743 Jena, Germany. - Email:
Anke.Burmester´@rz.uni-jena.de
Successful infection of Absidia glauca (Mucorales,
Mucoraceae) by Parasitella parasitica (Mucorales,
Mucoraceae) requires that the partners belong to
complementary mating types. These observations point
towards a physiological relationship between parasitism
and the sexual pathway. In all mucoralean fungi analyzed,
sexual differentiation depends on the synthesis of the sex
pheromone trisporic acid. Trisporic acid is synthesized via
the complementary biosynthetic action of both mating
types. One of the genes for an enzyme of the trisporic acid
biosynthesis pathway was cloned from host and parasite.
Expression studies at the transcriptional level show
transcripts only after stimulation by mating and infection.
DNA sequence analysis of the genomic surrounding detects
a second gene in close neighborhood of the first one, with
an unknown function. Nevertheless, this gene is transcribed
in P. parasitica. Recently, vectors were constructed
containing the gene for green fluorescent protein (GFP) for
transformation of A. glauca strains. Now, also in vivo
expression can be studies to obtain more insights in the
interaction of parasite and host.
1176 - Screening of environmental and clinical
Cladosporium isolates for cellobiose dehydrogenase
production
M. Shams 1* , A. Fazli 1 , A. Lotfi 2 & M. Razzaghi abyaneh 3
1 Dept.of Mycology, Faculty of Medical Sciences,Tarbiat
Modares University, P.O.Box:14115-111, Tehran, Iran. -
2 Dept.of Biochemistry, Tarbiat Modares University,
P.O.Box:14115-111, Tehran, Iran. - 3 Dept.of Myclogy,
Pasteur Institute of Iran, P.O.Box:13164, Tehran, Iran. -
E-mail: shamsm@modares.ac.ir