Handbook Part 2 - International Mycological Association

PS8-465-0394
Use of 18S rDNA and TGGE to study aquatic hyphomycetes in polluted surface and groundwater
M. Solé 1, G. Krauss 2
1 UFZ Centre for Environmental Research Leipzig-Halle in the Helmholtz Association, Department of Environmental
Microbiology, Permoser-Str. 15, 04318 Leipzig, Germany, 2 UFZ Centre for Environmental Research Leipzig-Halle in the
Helmholtz Association, Department of Environmental Microbiology, Theodor-Lieser-Str.4, 06120 Halle/Saale, Germany
Aquatic hyphomycetes initiate the degradation of organic material in rivers and ponds and are therefore efficient
contributors to the food web of aquatic ecosystems. Surprisingly, the litter is also colonised and degraded in aquatic
habitats contaminated by heavy metals or organic xenobiotic compounds. The ecology and biodiversity of aquatic
fungi is therefore of considerable interest and hence the composition and the dynamics of natural fungal communities
in polluted environments require further investigation.
We studied communities of aquatic hyphomycetes on alder leaves exposed in three surface water and two
groundwater habitats representing a pollution gradient due to sulphate, nitrate and heavy metals. Communities were
characterized with molecular and morphology-based methods. The genetic marker NS1/GC-fung was used for nested
PCR amplification followed by Temperature Gradient Gel Electrophoresis (TGGE). Generally, the molecular approach
revealed fewer phylotypes in surface waters than the morphology-based method. The opposite was found in
groundwater. Extremely low numbers of conidia and ergosterol concentrations were found in groundwater and in the
highly polluted surface water habitat H4. In the latter, after two weeks of leaf immersion only 1.6 conidia and 0.04
“micro” g ergosterol per mg dry leaf mass, as opposed to 927 conidia and 0.11 “micro” g ergosterol per mg dry leaf
mass in the moderately polluted surface water habitats H8 and H9 were observed.
Our data based on a methodologically combined approach show that harsh ecological conditions might delay
substantially the ecological key process of fungal leaf decomposition by changing fungal biodiversity.
PS8-466-0403
Congruence found among recombination rates and population ages for different populations of
Mycosphaerella graminicola
S Banke
Biological Inst., Copenhagen, Denmark
I wanted to test the simple hypothesis: that more recombination events are likely to be fixed in an older population
than in a younger population assuming similar population structure and environmental condition. Intragenic
recombination rates were estimated for 5 worldwide populations using 6 DNA sequence loci, in which intragenic
recombination was observed. We used information about population structure from earlier studies done on M.
graminicola to determine the age and demographic history of the five populations. The findings mostly support the
hypothesis of recombination rate reflecting population age. One local population of a relatively young age showed
a high recombination rate. High levels of directional gene flow from the ancestral population can be responsible for
carrying on the signal of recombination to newer populations in some cases.
PS8-467-0414
Population Genetic Studies Of Symbionts In Lichens With Different Propagation Modes
S Wornik, M Grube
Institute of Plant Sciences, Karl-Franzens University, Graz, Austria
Symbiotic associations of fungi with algae are regarded as an important key innovation in the evolutionary radiation
of ascomycetes. However, there is still a gap of knowledge concerning the symbiont selectivity patterns, especially at
the intraspecific scale.
In our population genetic study we focus on two species of Physconia with a comparatively high symbiont selectivity
and different propagation strategy. One species (P. distorta) is generally producing ascospores that sample algae
from a “pool” in the environment, while the other species (P. grisea) propagates both symbionts jointly by special
structures, the soredia. In both cases we observe a wide distribution of some haplotypes of lichen symbionts.
By comparing populations of the mycobiont and the associated photobiont we find diverse patterns between the
studied lichen species with different propagation modes. We show that the intraspecific variation of the symbionts of
the sexually reproducing lichen is similar across various altitudinal levels, whereas the highest gene diversity of the
asexually reproducing lichen is found between 200-400m. The photobiont diversity is comparable in both species and
photobiont switches between them seem to be frequent. The vegetatively reproducing mycobiont however shows
the lowest diversity of all investigated symbionts. We will compare these patterns also with findings in other lichen
species, and address the question whether photobiont selectivity could play a role in speciation.
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