Book of Abstracts (PDF) - International Mycological Association

IMC7 Monday August 12th Lectures
spread of non-outcrossing spores (species 2 and 3); c)
vectoring of vegetative mycelium by woodwasps and wood
material (species 4 and 5); d) use of single fungal strain as
a large-scale biocontrol agent (species 6). The results show
that fungal clones at one extreme are small and local; at the
other extreme, clones of the wood-inhabiting fungi are
capable of moving between widely separated locations and
have a pronounced impact on population structure of a
given species on trans- or even inter-continental scales.
Persistence of such clones in nature varies from several
years up to several decades. They are mainly characteristic
for forest areas under anthropogenic impact, with the
presence of stumps, wounds on living trees, burned areas
and exotic species.
23 - Sexuality and genetic variation in three boreal
Polypores possessing divergent niche requirements
H. Kauserud * & T. Schumacher
University of Oslo, Department of Biology, P.O.Box 1045
Blindern, 0316 Oslo, Norway. - E-mail:
haavarka@bio.uio.no
The population structure and sexuality of Fennoscandian
populations of three model species, the vulnerable
Phellinus nigrolimitatus and Fomitopsis rosea and the
common pioneer wood-fungus Trichaptum abietinum, was
investigated. Molecular support for a heterothallic mating
system in P. nigrolimitatus was found. Molecular data and
mating studies demonstrated that T. abietinum and F. rosea
have a heterothallic mating system. The observed genotype
distributions in the geographic populations of the model
species were mostly in accordance with Hardy-Weinberg
expectations. Our results suggest that the mating
populations are large and that panmictic conditions exist.
Although P. nigrolimitatus and F. rosea probably have
experienced decline in population sizes as a result of
negative impacts from forestry, no distinct heterozygote
deficits ascribed to inbreeding could apparently be
detected. The molecular markers revealed little genetic
differentiation among geographic populations of the three
model species, indicating high gene flow and good
dispersal ability. The geographic populations may be
regarded as subpopulations sharing the same gene pool. A
high number of mating types were present in one T.
abietinum and two F. rosea populations, a feature that may
indicate high genetic diversity. A high number of T.
abietinum and F. rosea genets occurred on single logs. In
P. nigrolimitatus fewer but larger genets that often
produced more than one basidiocarp occurred.
24 - Genetic structure of Daldinia loculata populations
H. Johannesson 1* , A. Guidot 2 , A. Dahlberg 1 & J. Stenlid 1
1 SLU, Forest Mycology and Pathology, Box 7026 SE-750
07 Uppsala, Sweden. - 2 SLU, ArtDatabanken, Box 7007
SE-750 07 Uppsala, Sweden. - E-mail:
hanna.johannesson@mykopat.slu.se
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Book of Abstracts
The genetic structure of the postfire ascomycete Daldinia
loculata was studied on both a local and a continental
scale. We were able to show endophytic establishment of
D. loculata by isolating mycelia from non-decayed wood
of birches. The distribution of genets was studied at one
Swedish forest site, and in all trees studied we found only
one, or occassionally two, unique genets per stem. The
relatively large genet in the stem apparently was one of the
parents of the offspring of the stromata attached to the tree,
while each stroma had one or several unique second
parents. Low levels of genetic differentiation among
Eurasian subpopulations were confirmed by analysing the
allelic distribution nuclear gene loci of 1 Russian and 6
Fennoscandian subpopulations. Taken together, these
results suggests that D. loculata consists of a long-lived
background Eurasian population of latent mycelia in nonburned
forests, established by ascospores dispersed from
scattered burned forest sites. When the trees die from a
forest fire, the latently established genets starts to decay the
wood, and the sexual reproduction is triggered. In order to
investigate the spatial distribution and origin of the parents
of the stromata, all vegetative genets and offspring of the
attached stromata were sampled at one burned forest site.
The sequence of highly variable nuclear gene loci were
analysed from each mycelium and the high level of unique
genets found indicates ascospore origin of all mycelia.
25 - Population genetics and dispersal biology of
endangered lichen species: some implications for lichen
conservation biology
C. Scheidegger * , J.-C. Walser, D. Yetman, S. Werth & C.
Sperisen
WSL Swiss Federal Research Institute, CH-8903
Birmensdorf, Switzerland. - E-mail: scheidegger@wsl.ch
Global populations of endangered lichen-forming fungi are
often highly fragmented and local populations are reduced
to critical size, e.g. in Erioderma pedicellatum. Especially
in heterothallic species such as Lobaria pulmonaria this
process is likely to reduce the survival probability of local
populations if genetic diversity is reduced. For instance, in
this species genetically depauperate populations seem to be
unable to reproduce sexually and therefore propagation is
limited to vegetative, symbiotic dispersal units. However,
the low range of these relatively large dispersal units limits
the local populations to rather low average population
densities. The study of the dispersal and post-dispersal
processes is therefore of prime importance to identify
critical distances among habitats, especially in managed
forests. PCR-based techniques were recently developed and
allow the detection of single symbiotic propagules. Further,
sets of markers with high levels of genetic variation will
become available and will allow to detect rare genotypes
which depend on conservation measures such as population
augmentation.