Book of Abstracts (PDF) - International Mycological Association

IMC7 Main Congress Theme IV: POPULATION DYNAMICS AND ECOLOGY Posters
In Portugal, as in many other countries, there are few
studies concerning macrofungi and there is much to be
known. The NE Portugal is no exception, and habitats like
oak forests and serpentine soil sites have not yet been
explored. The present study takes place in two different
habitats, a Quercus pyrenaica stand and a Quercus
rotundifolia in serpentine soil stand. The objective is to
characterize the macrofungal communities present in both
habitats and relate them with soil and vegetation variables.
We expect to find different mycota and that the influence
of environmental factors is different in the two habitats.
936 - Interspecific interactions between saprotrophic
basidiomycetes: Effect on gene expression and enzyme
activity
A.W. Branney * , L. Boddy & H. Rogers
Cardiff University, School of Biosciences, Cardiff
University, PO Box 915, Cardiff, CF11 3TL, U.K. - E-mail:
abranney@hotmail.com
Saprotrophic basidiomycetes rarely form monospecific
populations in the soil or organic substrata that they
inhabit, therefore interspecific mycelial interactions
continually occur. Gross outcome can either be deadlock
(where neither species gains headway) or replacement
(where one species wrests territory from the other).
Irrespective of the outcome, dramatic morphological
changes may occur in both mycelia. Morphological
changes are correlated with differences in physiology and
enzyme production, and may occur distant from the site of
interaction. Currently, there is little or no information on
spatial and temporal changes in gene expression and in
enzyme production in mycelia in soil, either when growing
alone or during interactions. In interactions between
Hypholoma fasciculare and Phlebia radiata, we test the
hypothesis that: (1) there is spatial and temporal variation
even in mycelia growing alone, related to morphological
differentiation and presence of substrates; (2) massive
changes occur in the vicinity of interactions; (3) changes
also occur elsewhere in support of the interaction front.
937 - Genetic sieves in sexual reproduction: sexual
spores of Aspergillus nidulans have lower mutation load
than asexual spores
J. Bruggeman * , P.J. Wijngaarden, A.J.M. Debets & R.F.
Hoekstra
Genetics Department, Wageningen University,
Arboretumlaan 4, 6703 BD Wageningen, The Netherlands.
- E-mail: judith.bruggeman@genetics.dpw.wau.nl
Whatever the evolutionary forces are for the widespread
occurrence of sexual reproduction, Mendelian transmission
is interwoven with it. This system ensures maximal
uncertainty for the transmission of genetic information,
thereby preventing parasitic genes or sequences to gain a
282
Book of Abstracts
transmission advantage. A disadvantage of this system is
that both low quality and high quality alleles have equal
chances of being transmitted to the progeny. Clearly,
evolution should favour processes within an individual that
alleviate this disadvantage either by selection on gamete
producing cells, on gametes or on support-relying zygotes.
We introduce the term 'genetic sieves' for these processes.
The haploid homothallic ascomycete fungus Aspergillus
nidulans is excellently suited to study genetic sieves due to
important properties, which we will explain on our poster.
We predict that 'genetic sieves' in the sexual reproduction
cycle prevent or slow down the accumulation of deleterious
mutations. We tested this in a mutation accumulation
experiment for both sexually selfing and asexually
reproducing lines. In this poster we present the result of
this mutation accumulation experiment that support our
prediction. From the fitness data we calculated mutation
rate and mean fitness effect of a mutation using the
Bateman-Mukai equations. This gives us insight in the
operation of this sieve.
938 - Armillaria species and the legacy of forest
disturbance in Ozark Highlands landscapes of the
central U.S.A.
J.N. Bruhn 1* , R.P. Guyette 2 , J.D. Mihail 1 & J.M. Kabrick 3
1 Dept. of Plant Microbiology & Pathology, University of
Missouri, 108 Waters Hall, Columbia, Missouri, 65211,
U.S.A. - 2 School of Natural Resources, University of
Missouri, 203 ABNR, Columbia, Missouri, 65211, U.S.A. -
3 Missouri Department of Conservation, 1110 South
College Avenue, Columbia, Missouri, 65201, U.S.A. - Email:
bruhnj@missouri.edu
Relationships between disturbance regimes and diverse life
forms are being studied to understand forest landscapes and
their responses to management. Disturbance regimes were
characterized by abrupt ring-width reductions in Pinus
echinata and fire frequency. Disturbance indices are
correlated with topographic roughness and the abundance
of certain bird, reptile, soft mast fruit, Armillaria, and tree
species. In turn, Armillaria spp. contribute to forest
decline, functioning both as long-lived disturbance factors
and as catalysts for further disturbance, in a feedback
manner. Three Armillaria spp. occur regionally with
different distributions. Nearly ubiquitous, A. mellea often
occurs alone on thermally exposed aspects; A. tabescens
and A. gallica occur typically on ridges vs. protected
aspects in more rugged landscapes, respectively.
Behaviorally, A. gallica fruits infrequently, produces most
rhizomorphs, and causes least disease. Most root disease is
caused by A. mellea, which fruits prolifically but produces
fewer rhizomorphs. Less abundant, A. tabescens produces
the most limited rhizomorph systems, fruits well, and
causes some disease. Armillaria spp. take advantage of
successive stress events to gradually invade infected root
systems. Tree mortality, mostly Quercus coccinea, Q.
velutina, and Cornus florida, is often associated with root
crown invasion by A. mellea or A. tabescens. Greater
mortality on exposed aspects is associated with the
exclusive presence of A. mellea.