Book of Abstracts (PDF) - International Mycological Association

IMC7 Main Congress Theme V: CELL BIOLOGY AND PHYSIOLOGY Posters
1102 - Ruderal and combatative strategies in insect
pathogenic fungi examined by EST analysis
F.M. Freimoser * , G. Hu & R.J. St. Leger
Department of Entomology, University of Maryland, 4112
Plant Sciences Building, College Park, MD, 20742, U.S.A.
- E-mail: ff34@umail.umd.edu
Metarhizium anisopliae (Ascomycota) and Conidiobolus
coronatus (Zygomycota) are facultative saprophytes that
are pathogenic to many insect species. About 2000 EST
cDNA clones from each species were sequenced to analyze
gene expression during growth on host insect cuticle and/or
nutrient rich media. Proteases were the commonest
transcripts with both species producing multiple subtilisins,
as well as trypsin, metalloprotease and aspartyl protease
activities capable of degrading host tissues and disabling
anti-microbial peptides. However, compared to M.
anisopliae, C. coronatus produced many fewer
extracellular hydrolases (e.g., no phospholipases),
antimicrobial agents, toxic secondary metabolites and no
ESTs with putative roles in the generation of antibiotics.
Instead, C. coronatus produced a much higher proportion
of ESTs encoding ribosomal proteins and enzymes of
intermediate metabolism consistent with the rapid growth
characteristics of C. coronatus. These results are consistent
with M. anisopliae using a combatative strategy to defend
captured resources, while C. coronatus has modified the
saprophytic ruderal-selected strategy using rapid growth to
overwhelm the host and exploit the cadaver before
competitors overrun it. Both strategies are consistent with
specialization to pathogenicity. Thus, induction of
proteases by host cuticles (mucoralean fungi do not
produce proteases under these conditions) demonstrates
that C. coronatus is adapted to entomopathogenicity.
1103 - Induction of defense-related enzyme activities in
poplar roots inoculated with compatible and noncompatible
isolates of Paxillus involutus
A. Gafur 1* , A. Schützendübel 2 & A. Polle 2
1 Department of Plant Protection, University of Lampung,
Jalan S. Brojonegoror 1, Bandar Lampung 35145,
Indonesia. - 2 Institute for Forest Botany, University of
Göttingen, Büsgenweg 2, D-37077 Göttingen, Germany. -
E-mail: gafur@uwalumni.com
Defense-related enzyme activities, especially those of
peroxidases, were examined in short roots of control, noncompatible
and compatible interactions between hybrid
poplar (Populus tremula L. x P. tremuloides Michx.) and
Paxillus involutus (Batsch) Fr. Peroxidase activities
increased significantly in poplar inoculated with noncompatible
isolate of the fungus compared to control, an
indication that the plant recognized invasion of the noncompatible
isolate and subsequently responded with
activation of the defense responses. Elevated levels of the
enzymatic activity were maintained after seven weeks of
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Book of Abstracts
inoculation. On the other hand, accumulation of the same
enzyme was not detected in compatible associations. The
failure of induction of peroxidase activity in mycorrhizal
root tips may suggest low-scale or even lack of plant
defense responses in the compatible association between
poplar and P. involutus. In other experiments, an
appreciable amount of hydrogen peroxide (H 2O 2) was
surprisingly detected only in compatible tissues, leading to
speculation on the presence of stress conditions in the
tissues. It has to be noted, however, that the accumulated
H2O 2 in the tissues may have been released by fungal
mycelia forming mantle and Hartig net in compatible
interactions. It has been recognized that mycelia of some
ectomycorrhizal fungi, including P. involutus, produce
H2O 2.
1104 - Overflow of organic acids in Penicillium
simplicissimum
M. Gallmetzer & W. Burgstaller *
Institute of Microbiology, Technikerstrasse 25, 6020
Innsbruck, Austria. - E-mail:
wolfgang.burgstaller@uibk.ac.at
The efficiency of carbon source utilization by filamentous
fungi is strongly influenced by environmental conditions.
This is of advantage in biotechnological processes, because
it is easier to vary environmental conditions than to change
the metabolic properties of a fungus. Understanding how
environmental conditions influence a fungal metabolism is
therefore important. We used continuous cultivation to
study the influence of the specific growth rate and of
environmental conditions (glucose-, ammonium-, nitrate-,
phosphate- and potassium-limited growth; various pH
values, osmolarities and inhibitors) on the excretion of
organic acids by Penicillium simplicissimum. P.
simplicissimum is used in heterotrophic metal leaching
processes. Citrate was under all conditions the main
excreted intermediate. This excretion can be termed an
energy spilling process, because it avoids the formation of
NADH. The sum of the excreted organic acids was
inversely correlated with the biomass yield. Glucose uptake
was strongly influenced by the specicfic growth rate, but
only weakly by the tested environmental conditions. The
highest carbon overflow was observed with phosphate
limitation (12% of the total consumed carbon, compared to
1% during glucose limitation). Stress factors (alkaline pH,
high osmolarity, addition of benzoic acid) in general
increased both glucose uptake and carbon overflow.
1105 - Calcium oxalate and gypsum on the thallial
surface of the lichen Ramalina lacera exposed to
polluted air
J. Garty 1* , P. Kunin 1 , J. Delarea 2 & S. Weiner 3
1 Tel Aviv University, Dept. of Plant Sciences, Tel Aviv
69978, Israel. - 2 Tel Aviv University, Lab. Electron
Microscopy, Tel Aviv 69978, Israel. - 3 Weizmann Inst. of