March 2008 - Mycological Society of America

were Perconia, Gaeumannomyces, Fusarium, Anguillospora, and
many unknown species. We found that many of the fungi are infected
by viruses. The majority of these viruses may be newly discovered and
previously unknown. Future studies will aim to understanding the role
of the discovered mycoviruses on the character and intensity of plantfungus
interactions and possibly how disturbances, such as fire, can influence
virus-fungal-plant interactions. Poster
Boerstler, Boris*, Raab, Philipp and Redecker, Dirk. Institute of
Botany, University of Basel, Hebelstr.1, CH-4056 Basel, Switzerland.
boris.boerstler@unibas.ch. Mitochondrial large ribosomal subunit
sequences as potential marker for population studies of Glomus intraradices.
Arbuscular mycorrhizal fungi (AMF) form symbioses with
the majority of land plants. Glomus intraradices is a widespread member
of this group which was found in an extremely broad range of habitats,
indicating a high tolerance for a multitude of environmental factors.
Despite this ecological versatility, almost nothing is known about
the local and geographic structure of this fungal species which might
reveal specialized ecotypes. As the well-established marker genes of
the nuclear-encoded rDNA subunits and internal transcribed spacers
(ITS) display sequence heterogeneity even within single fungal spores
we have developed a nested PCR approach for the mitochondrial
rDNA large subunit (mtLSU). These sequences display no intra-isolate
heterogeneity but different haplotypes can be distinguished among isolates
of G. intraradices. The development of highly specific primer sets
makes it possible to obtain mtLSU sequences of G. intraradices from
colonized roots. The varying content of introns in the analyzed gene region
represents a further feature to distinguish genotypes. Therefore
mtLSU has the potential to be a highly sensitive marker for population
studies of G. intraradices. Contributed Presentation
Bogale, Mesfin*, Wingfield, Michael J., Steenkamp, Emma T. and
Wingfield, Brenda D. Forestry and Agricultural Biotechnology Institute
(FABI), University of Pretoria, Pretoria, South Africa. mesfin.bogale@fabi.up.ac.za.
Characterization of Fusarium oxysporum
isolates from Ethiopia using SSR, AFLP and DNA sequence analyses.
Fusarium oxysporum is known for the wilt and rot diseases that it
causes in many plant species. However, little is known regarding the
genetic diversity of this fungal species in Ethiopian agriculture. We
used SSR, AFLPs and DNA sequence analyses to study 32 Ethiopian
isolates. For comparative purposes, we also included strains representing
18 formae speciales, and GenBank sequences representing the
three phylogenetic clades in this species. The three methods separated
the strains into three lineages, which corresponded with the three clades
known to reflect groups in F. oxysporum. Five translation elongation
factor-1 alpha nucleotide sites were found to be fixed differently among
the lineages, further supporting the separation of the lineages. Thirty of
the Ethiopian isolates grouped in Lineage 2, whereas the remaining two
isolates grouped in Lineages 1 and 3. The genetic diversity observed
among the Ethiopian isolates was also low. This most probably reflects
the nature of the Ethiopian agricultural system that heavily relies on
local crop varieties, thereby restricting the introduction of new genotypes
of the fungus via infected seeds. The 18 formae speciales did not
separate according to host, with any of the three DNA-based techniques
used. This confirmed that pathogenicity of isolates does not necessarily
correlate with phylogenetic grouping. Contributed presentation
Bogale, Mesfin*, Wingfield, Michael J., Steenkamp, Emma T. and
Wingfield, Brenda D. Forestry and Agricultural Biotechnology Institute
(FABI), University of Pretoria, Pretoria, South Africa. mesfin.bogale@fabi.up.ac.za.
Species-specific primers for Fusarium
redolens and a PCR-RFLP technique to distinguish among three
clades of Fusarium oxysporum. The presence of strains with intermediate
macroconidial sizes between F. redolens and F. oxysporum
makes morphological differentiation of these species problematic. The
PCR-RFLP technique developed to differentiate these species does not
distinguish F. redolens from F. hostae. Grouping of isolates into the
three phylogenetic clades of F. oxysporum requires DNA sequencing
and inclusion of strains/sequences representing each clade. DNA se-
8 Inoculum 59(2), March 2008
quencing is, however, not available to most plant pathologists, especially
to those in the developing world. To solve these problems, we
used nucleotide sequences from the translation elongation factor 1
alpha (TEF-1 alpha) genes of these species and their close relatives. We
aligned these sequences to design F. redolens-specific primers, and to
identify restriction sites that discriminate among the three clades of F.
oxysporum. The F. redolens-specific primers distinguished this species
from all others included in the study based on the presence of an amplification
product only in F. redolens. Restriction of F. oxysporum
TEF-1 alpha products with endonucleases MseI and AluI resulted in
three TEF-1 alpha-RFLP patterns. These PCR-RFLP patterns corresponded
with the three clades of F. oxysporum. These techniques provide
simple and inexpensive diagnostic methods for the identification
of F. redolens and members of the three clades of F. oxysporum. Contributed
Presentation
Bonito, Gregory* and Vilgalys, Rytas. Duke University, Durham, NC
27708, USA. gmb2@duke.edu. Molecular ecology of truffles (Tuber)
and their mycorrhiza. Truffles belonging to the genus Tuber are mycorrhizal
fungi characterized by belowground fruitbody production and
a northern hemisphere distribution. Of the 100 or so described species
of Tuber worldwide, a dozen or so species have economic value and are
harvested commercially. This has stimulated interest to better understand
truffle ecology. DNA sequencing is a common component in systematics
and ecological studies of mycorrhizal communities. The public
database Genbank includes approximately 30 unidentified
ectomycorrhiza submissions that BLAST closest to Tuber, and another
30 accessions from unidentified Tuber sp. sporocarps. Our research
on the phylogenetic relationships within the genus Tuber has resulted
in a Tuber phylogeny and has resolved 7 well-supported clades. In this
study, we analyzed unidentified Tuber collections and mycorrhiza from
our field studies and from Genbank accessions in a phylogenetic framework
to determine the identification of unidentified samples and to ascertain
the prevalence of ‘novel’ or undocumented lineages. Our results
show that the majority of unidentified Tuber sequences belong to noneconomically
important (and less studied) species within the Puberulum
and Maculatum clades. Further ecological insights into host, habitat,
and geographical ranges of these species are discussed. Poster
Branco, Sara. University of Chicago, Chicago, IL 60637, USA; The
Field Museum, Chicago, IL 60601, USA. sbranco@uchicago.edu. Is
there a serpentine ectomycorrhizal community? Serpentine soils are
extreme environments rich in heavy metals and poor in nutrients that
host depauperate plant communities with high rates of endemism. I am
investigating whether the symbiotic fungal communities from serpentine
forests follow the same pattern seen for plants. I surveyed the ectomycorrhizal
(ECM) communities from serpentine and non-serpentine
oak forests in northeastern Portugal using the rDNA Internal
Transcribed Spacer (ITS) region and found enormous diversity. All
three forests showed very different and rich communities with very low
ITS type overlap. Additionally, sampling of fungi in the same forest in
consecutive years revealed a tremendous ITS type annual turnover. The
pattern of species-poor communities found for plants does not seem to
hold for ECM fungi and the existence of endemic ECM serpentine
species is still unclear. However, the detection of many ITS types restricted
to the serpentine forest is an indication of putative endemics. A
few ITS types were detected in serpentine and non-serpentine forests,
suggesting the existence of plastic species tolerant to both soils. These
results document high ECM diversity associated with Mediterranean
oak forests. Further investigation is needed to clarify the existence of
particular ECM communities specifically associated with serpentine
soils and determine the role of this extreme habitat in the evolution of
symbiotic fungi. Contributed Presentation
Brooks, Micheal C., Powell, Martha J.*, Blackwell, Will H., Letcher,
Peter M. and Wakefield, William S. Department of Biological Sciences,
The University of Alabama, Tuscaloosa, AL 35487-0344, USA.
mpowell@biology.as.ua.edu. Detection of chytrid fungi involved in
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