Book of Abstracts (PDF) - International Mycological Association

IMC7 Thursday August 15th Lectures
they are poorly known. In particular, the scale of endophyte
diversity, and the nature of endophyte-host interactions, are
not well understood. Drawing from extensive field studies
at scales ranging from individual leaves to disparate sites
across lowland Panama, I will discuss evidence for spatial
structure, temporal variability, host affinity, and horizontal
transmission among tropical forest endophytes. Drawing
from experimental results, I will describe a potential
mechanism for host affinity based on defensive chemistry
of host leaves. Using molecular sequence data (nrDNA:
ITS1, ITS2, 5.8s), I will show that tropical endophytes are
diverse at both low and high taxonomic levels, and will
discuss phylogenetic patterns of diversity. Finally, I will
discuss roles of endophytes in mediating host defense
against foliar pathogens, and will assess general costs and
benefits of endophyte infection in tropical woody
angiosperms.
322 - Effect of agricultural management on diversity of
root endophytes: the role of dark septate endophytes
E.M. Wilberforce 1* , G.W. Griffith 1 , L. Boddy 2 & R.
Griffiths 3
1 Institute of Biological Sciences, University of Wales
Aberystwyth, Penglais, Aberystwyth, Ceredigion SY23
3DA, Wales, U.K. - 2 School of Biosciences, Cardiff
University, PO Box 915, Cardiff CF10 3TL, Wales, U.K. -
3 National Botanic Garden of Wales, Middleton Hall,
Llanarthne, Carmarthenshire, SA32 8HG, Wales, U.K. - Email:
emw96@aber.ac.uk
Three mesotrophic grassland sites of similar physical
characteristics but differing management histories were
chosen to test the hypothesis that agricultural disturbance
has a deleterious effect on the diversity of fungi inhabiting
plant roots and the prevalence of potentially pathogenic
species (e.g. Fusarium spp.). Species abundance data were
collected for fungi isolated from surface sterilised root
samples (>40 taxa). Shannon and Brillouin indices of
diversity, TWINSPAN and detrended correspondence
analysis were applied to the community data. Quantitative
ordination separated the samples by site showing that the
communities differed in fields of contrasting management.
Species presence and absence appeared to be affected
seasonally; site differences were manifested in relative
abundance. Diversity did not appear to vary by site, but a
methodological explanation for this is proposed. Sterile
dark septate endophytes (DSE) were shown among the
most abundant groups at all sites, and diversity among
these fungi was investigated using a PCR-based approach.
It is suggested that DSE, in addition to the overall diversity
of root-colonising species, may be implicated in relating
plant root communities and plant health. Microcosm
systems have been used to study the dynamics of root
colonization by DSE, as well as Fusarium spp.
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Book of Abstracts
323 - Rock inhabiting fungi and lichen photobionts:
symbiotic or antibiotic interactions?
A. Gorbushina 1* , A. Beck 2 & A. Schulte 1
1 Geomicrobiology, ICBM, Oldenburg University, P.O.Box
2503, D-26111 Oldenburg, Germany. - 2 Lehrstuhl für
Pflanzensystematik, Universität Bayreuth, Universitätsstr.
31, D-95447 Bayreuth, Germany. - E-mail:
anna.gorbushina@uni-oldenburg.de
Phototrophs are considered to be the first land colonisers,
although this ability is often supported by mutualistic
associations with fungi. Furthermore bare rock surfaces are
frequently dominated not by phototrophs, but by free-living
and symbiotic ascomycetes. On desert rock surfaces
lichens often yield and in the harshest environments only
microcolonial fungi (MCF) are present. MCF - highly
stress-tolerant free-living organisms - could represent the
remnants of symbiotic associations, which implies their
capability to interact with photobionts. Four typical MCF
were cultivated with 4 lichen photobionts isolated from
similar desert locations. The relations between the partners
were investigated by electron microscopy and histological
methods. After several months of cultivation a structure
involving both partners has been developed. Photobiont
cells were not changing size, but fungal branching was
more expressed in the vicinity of green algal cells.
Histological analysis of interwoven colonies exhibits
spatial adjustment of the partners. After continued
cultivation algae lost vitality. Only one MCF strain enabled
survival of the algae tested. The absence of antibiotic
influences in the first stage of the experiment hints to an
universal ability of MCF to form unstable mutualistic
relations with lichen photobionts. The later loss of
mutualistic balance may be connected to the diverse
taxonomic position of the MCF strains in question.
324 - Cyanobiont diversity in ecological lichen guilds
J. Rikkinen
Department of Applied Biology, PO Box 27, 00014
University of Helsinki, Finland. - E-mail:
jouko.rikkinen@helsinki.fi
Many cyanolichen species are organized into guilds around
groups of phylogenetically related cyanobacteria. In a
study of old-growth associated cyanolichens in central
Finland all bipartite epiphytes were found to house closely
related Nostoc strains and most of the thalli contained one
specific strain. While the cyanobionts of all these lichens
were closely related, the lichen-forming fungi were
necessarily not. Moreover, some related terricolous species
associated with a different group of Nostoc symbionts and
thus belonged to a different ecological guild. A comparison
with cyanolichens from North America and East Asia
revealed concurrent patterns. Thus, a similar specificity
was evident on all spatial scales ranging from single tree
trunks to global distributions. All lichen-forming fungi