Book of Abstracts (PDF) - International Mycological Association

IMC7 Friday August 16th Lectures
433 - Primary decayers - a key to understanding biodiversity
in decaying wood?
J. Heilmann-Clausen
Danish Forest and Landscape Research Institute,
Hørsholm Kongevej 11, 2970 Hørsholm, Denmark. - Email:
jhc@kvl.dk
Primary decayers, here defined as fungi initiating and
causing extensive wood decay, have in several cases been
found to be important determinants of subsequent decay
development and species composition in decaying wood.
Based on own research this concept of decay pathways is
reviewed, and it is discussed if such pathways are well
defined and whether they are shaped by interspecific
interactions, by passive facilitation, or both. Further, the
importance of decay pathways for biodiversity in decaying
wood is considered, and it is discussed whether decay
pathways are important to consider in the development of
management guidelines aiming to preserve and restore
biodiversity in forests.
434 - Tritrophic relationships in the phyllosphere:
fungal parasites and hyperparasites in action
L. Kiss
Plant Protection Institute, Hungarian Academy of
Sciences, H-1525 Budapest, P.O. Box 102., Hungary. - Email:
LKISS@NKI.HU
Traditionally, the interactions between plant parasitic fungi
and host plants are regarded as closed, two-species
systems. However, both parasites and their hosts are, in
fact, components of complex multitrophic interactions in
which parasitic fungi are often attacked and killed by
hyperparasites or other antagonists. Parasites, by definition,
have a negative effect on host fitness, so hyperparasitism
should be favourable for plants infected with parasites.
However, studies on the possible role of hyperparasites in
the natural control of plant parasites are missing from the
literature. There are a few quantitative studies even on the
natural occurrence of hyperparasitism that represents only
the first step towards evaluating the impact of
hyperparasites on host fungal and plant populations in
nature. This paper synthesizes the current knowledge on
structural, physiological and evolutionary aspects of natural
host-parasite-hyperparasite relationships. A case study is
also presented in which the effects of Ampelomyces
hyperparasites on the fitness of powdery mildew infected
Lycium halimifolium plants were studied by measuring the
chlorophyll content of the healthy and infected leaves with
and without hyperparasites in the field.
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Book of Abstracts
435 - Understanding the communicating mycelium -
Translocation, past present and future
S. Olsson
Dept of Ecology, Royal Veterinary and Agricultural
University, Thorvalsensvej 40, DK-1871 Frederiksberg C,
Denmark. - E-mail: stefan.olsson@ecol.kvl.dk
A fungal mycelium with its cytoplasmic continuum is a
single organism. The mycelium is thus a network of
communicating daughter nuclei. Communication consists
of both signalling and sharing of material resources, like
nutrients and energy. The study of nutrient and organelle
translocation has a long history in mycology and some
classical works will be briefly presented. The difference
between large mycelia and the unicellular organisms in
need for resourse redistribution are mainly two. 1. Need for
fast high capacity nutrient translocation: Four different
mechanism has been suggested, simple diffusion, simple
diffusion + active uptake, active translocation by
cytoplasmic movements and pressure driven bulk flow
through vessel hyphae. There appear to be large differences
between fungal mycelia of different species in their ability
to translocate nutrients which might reflect the mechanisms
employed. 2. Need for nutrient storage: To be able to
scavenge nutrients quickly from the environment for
redistribution there has to be efficient uptake systems and
somewhere to store what has been taken up. Nutrients are
taken up as small molecules but their storage have to be in
osmotically neutral form. Great advances have been made
in understanding the mechanisms for nutrient reallocation
in mycelia but there are still much to do. Long distance
signalling as well as nutrient storage needs attention in
future research to be able to understand the physiology of
mycelial organisms.
436 - Bidirectional transport - an insurmountable
obstacle to the use of tracer isotopes in quantitative
translocation studies?
B.D. Lindahl
Dept. of Forest Mycology and Pathology, SLU, Box 7026,
SE-75007, Uppsala, Sweden. - E-mail:
bjorn.lindahl@mykopat.slu.se
Tracer isotopes have been used in a long range of studies to
demonstrate translocation of various substances through
fungal mycelia. In a microcosm experiment, translocation
was studied in rhizomorphs of the wood rotting fungus
Hypholoma fasciculare. Non-destructive electronic
autoradiography was used in combination with the two
radioactive phosphorus isotopes 32P and 33P to show that
phosphorus was transported in two directions
simultaneously. This experiment confirms earlier studies
suggesting that phosphorus, and most likely a range of
other substances, are transported by mechanisms based on
circulation throughout the mycelium rather than direct
unidirectional transport from sources to sinks. The net