Book of Abstracts (PDF) - International Mycological Association

IMC7 Main Congress Theme III: PATHOGENS AND NUISANCES, FOOD AND MEDICINE Posters
including number of septa and size of conidia, among
Indonesian isolates of C. heterostrophus existed, an
indication that Indonesian C. heterostrophus might have
originated from different ancestors. In contrast,
pathogenicity of each isolate measured by disease
incidence on several corn varieties was not significantly
different. Disease severity of the corn varieties inoculated
with each isolate was also relatively the same. The results
imply that the corn varieties tested possess potential risks
of southern corn leaf blight outbreaks.
824 - Diagnosis of cryptic microbes based on ITS2
rRNA secondary structure information
A. Gargas 1* & P.T. DePriest 2
1 Dept. of Botany, University of Wisconsin, Madison, 132
Birge Hall, 430 Lincoln Dr, Madison, WI 53706, U.S.A. -
2 Dept. of Botany, National Museum of Natural History,
Smithsonian Institution, Washington, DC 20560, U.S.A. -
E-mail: agargas@facstaff.wisc.edu
Conventional techniques of isolating and identifying fungi
or other cryptic microbes are time-consuming and
expensive, limiting their utility for rapid and widespread
surveys. We invented a novel method for detection and
identification of microbes including those never before
isolated or identified. This approach relies on analyses of
the internal transcribed spacer 2 (ITS2) rDNA sequences -
highly variable regions flanked by the 5.8S and 28S
ribosomal subunits within nuclear DNA. After determining
secondary structures of ITS2 rRNAs we identify nucleotide
motifs between 20 and 50 nt in length within each primary
sequence. These signature sequences, readily defined and
present in high copy number, allow taxonomic diagnoses of
known and unknown microbes from various substrates
including agricultural, medical and ecological samples.
Such sequences are readily adapted for use with probing
techniques including PCR, microarray assays or other
molecular detection methods.
825 - First report of Coniothyrium stem canker on E.
camaldulensis in Ethiopia
A. Gezahgne * , J. Roux & M.J. Wingfield
Department of Plant Pathology and Microbiology, Tree
Pathology Co-operative Programme (TPCP), Forestry and
Agricultural Biotechnology Institute (FABI), University of
Pretoria, Pretoria 0002, South Africa. - E-mail:
alemu@fabi.up.ac.za
During a survey of Eucalyptus diseases in Ethiopia, a
serious stem canker disease was discovered on E.
camaldulensis trees at several localities in the South and
South Western parts of the country. The disease is
characterised by the presence of discrete necrotic lesions,
stem cankers, cracking of the stems, production of kino
pockets in the wood, as well as malformation of stems.
248
Book of Abstracts
These symptoms are similar to those caused by
Coniothyrium zuluense in South Africa. The aim of this
study was to positively identify the causal agent of the
disease in Ethiopia. This was achieved by sequencing the
ITS region of the rRNA operon for a representative set of
isolates. Sequences for the Ethiopian isolates were
compared with those from authenticated isolates collected
in South Africa, Thailand and Mexico. Based on these data,
the Ethiopian isolates were shown to group more closely
with those from South Africa, than with those from other
areas. This study represents the first report of C. zuluense
and its associated disease in Ethiopia. Currently the disease
is causing considerable losses in yield and quality of timber
and it also impacts negatively on the lives of subsistence
farmers. We are currently studying additional isolates of
the fungus and utilising sequences of different genes to
study the phylogenetic relationships between C. zuluense,
from a wide range of countries.
826 - Enzyme mediated infection of host Pinus short
lateral roots by Tricholoma matsutake
W. Gill 1 , K. Suzuki 2 , M. Brown 3 & C. Mohammed 4*
1 Tasmanian Institute of Agricultural Research, 13 St Johns
Ave, New Town, Tasmania 7008, Australia. - 2 Laboratory
of Forest Botany, Graduate School of Agricultural and Life
Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku,
Tokyo 113-8657, Japan. - 3 Huon Valley Mushrooms, Main
Road, Glen Huon, Tasmania 7109, Australia. - 4 School of
Agricultural Science, University of Tasmania, GPO Box
252-54, Tasmania 7001, Australia. - E-mail:
caro.mohammed@utas.edu.au
Tricholoma matsutake (Ito et Imai) Sing. (Matsutake) is an
edible mycorrhizal basidiomycete highly prized in Japan
for its culinary and medicinal properties and historical
social significance. However, the natural supply of
Matsutake in Japan is in decline and domestic demand
exceeds supply. Consequently, the development of a viable
commercial artificial cultivation system for this mushroom
is of prime concern. In both natural conditions and artificial
culture, Matsutake forms morphologically atypical
ectomycorrhizas on host Pinus short lateral roots.
Furthermore, aspects of the mushroom's nutrition are
unusual and it is this atypical interaction which must be
understood in order to devise an artificial cultivation
system. Here, we present evidence of host infection and the
parallel ability of T. matsutake to form a range of plant cell
wall degrading hydrolytic enzymes in artificial culture. The
hydrolytic enzymes tested were detected over a range of
activities but the majority peaked after 2 or 3 weeks of
incubation. Conversely, xylosidase and glucosidase
enzymes were detected in comparatively high activities
which did not peak but rather increased in activity over the
duration of the assay. The significance of the hydrolytic
enzymes produced in terms of Matsutake ectomycorrhizal
establishment, development and observed morphology is
discussed.