Book of Abstracts (PDF) - International Mycological Association

IMC7 Tuesday August 13th Lectures
investigations showed the capacity of TEs to restructure the
F. oxysporum genome in interesting ways and their
potential as valuable tools for tracing populations.
160 - Fusarium species big and small, and the interface
between systematics and population genetics
D.M. Geiser
Penn State University, Department of Plant Pathology,
University Park, PA 16802, U.S.A.
Multilocus phylogenetic approaches have revolutionized
our view of species in fungi, particularly in the genus
Fusarium. Using these approaches, phylogenetic units can
be identified that correspond to coherently defined species,
within which varying degrees of phylogenetic structure are
observed. Deciding where to draw the line between species
and subspecific lineages requires consideration of a variety
of phenotypic, biogeographic and ecological factors. In this
talk, I will compare and contrast several fusaria that have
been well-characterized phylogenetically, discussing how
species are usefully delimited and what we know about
genetic structure within those species. Case studies will
include Fusarium avenaceum (little phylogenetic
structure), F. hostae (some phylogenetic structure), F.
proliferatum (much phylogenetic structure) and species
lineages of the F. solani complex (varying levels of
phylogenetic structure). As has been demonstrated in other
groups of fungi, phylogenetic partitions within species may
be useful as landmarks for defining the boundaries within
which population genetic processes occur in Fusarium. The
DNA sequence databases of Fusarium species that have
emerged from these studies are also extremely useful as
tools for identification.
161 - Phylogenetic analysis of Fusarium based on
partial TEF-1α gene sequences
R. Kristensen * , M. Torp, A.K. Knutsen, B. Kosiak & A.
Holst-Jensen
National Veterinary Institute, Ullevålsveien 68, P.O.Box
8156 Dep., 0033 Oslo, Norway. - E-mail:
ralf.kristensen@vetinst.no
In an attempt to develop rapid molecular detection methods
for economically important mycotoxin producing Fusarium
species, we have sequenced a part of the translation
elongation factor 1α (TEF-1α) gene of more than 13
species of the sections Sporotrichiella,
Roseum/Arthrosporiella, Gibbosum and Discolor. This
gene was chosen because it was expected to provide a high
degree of phylogenetic signal and because the gene
phylogeny and the taxon phylogeny in related taxa has
been reported to be highly concordant. Our sequence data
were combined with additional data retrieved from
sequence databanks, aligned and subjected to phylogenetic
analyses (PAUP*). The resulting phylogeny largely
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Book of Abstracts
supports the subdivision of the taxa into the four sections,
but a few exceptions were observed indicating that the
sections Sporotrichiella and Discolor are polyphyletic. The
taxa representing the section Roseum/Arthrosporiella were
found to form a monophyletic clade, but our results suggest
that it may be more appropriate to include some of the taxa
currently classified in the sections Sporotrichiella and
Discolor in section Roseum/Arthrosporiella. We found a
high degree of concordance between the clades and taxa
known to produce DON/nivalenol and T-2/HT-2
mycotoxins. The delimitation of taxa is discussed in light
of the observed phylogeny.
162 - Evolution of the Fusarium graminearum species
complex
K. O'Donnell * & T. Ward
USDA-ARS-NCAUR, 1815 N. University, Peoria, IL 61604,
U.S.A. - E-mail: kodonnell@mail.ncaur.usda.gov
Fusarium head blight or scab of cereals is one of the most
devastating plant diseases worldwide. These pathogens
cause significant reduction in seed quality and yields and
often contaminate seeds with trichothecene and estrogenic
mycotoxins. Genealogical concordance phylogenetic
species recognition was used to investigate species limits
within this complex in order to understand the host range,
geographic distribution and mycotoxin potential of these
fusaria. Because trichothecene chemotypes are not well
correlated with the species phylogeny, we investigated the
evolutionary history of the trichothecene mycotoxin gene
cluster. Results of these phylogenetic analyses
demonstrated that polymorphism within these virulenceassociated
genes is trans-specific and appears to have been
maintained by balancing selection acting on chemotype
differences that originated in the ancestor of this important
group of plant pathogens.
163 - Medicinal mushrooms: Past, present and future
S.P. Wasser
Institute of Evolution, University of Haifa, Mt. Carmel,
Haifa 31905, Israel. - E-mail:
spwasser@research.haifa.ac.il
Medicinal mushrooms have been known in Oriental
medicine for hundreds of years as beneficial for health. In
2001, the value of world mushroom production and
medicinal mushroom products was estimated to be worth
approximately 18 billion US dollars. Mushrooms make up
a vast and yet largely untapped source of powerful new
pharmaceutical products. Many if not all Basidiomycetes
mushrooms contain biologically active polysaccharides in
fruit bodies, cultured mycelium, and culture broth. The data
about mushroom polysaccharides are summarized for 651.
These polysaccharides are of different chemical
composition; the main ones comprise the group of β-