Book of Abstracts (PDF) - International Mycological Association

IMC7 Tuesday August 13th Lectures
170 - TNF-α and NO production from macrophages is
enhanced through up-regulation of NF-κB by
polysaccharides purified from Agaricus blazei Murrill
S. Kawakami 1* , K. Minato 2 , T. Hashimoto 1 , H. Ashida 3 &
M. Mizuno 1
1
Graduate School of Science and Technology, Kobe
University, Kobe, 657-8501, Japan. - 2 Miyagi Agricultural
3
College, Sendai, 982-0215, Japan. - Faculty of
Agriculture, Kobe University, Kobe, 657-8501, Japan. - Email:
ksachiko@ans.kobe-u.ac.jp
The Basidiomycete fungus Agaricus blazei Murrill has
medically been used as a health food for the prevention of
cancer. We chromatographically purified polysaccharide
from alkaline-soluble fraction of A. blazei, which showed
the highest activity of TNF-α and NO production from
macrophage cell line, RAW264.7. The result of time course
experiments on TNF-α and NO production from
RAW264.7 stimulated with the purified polysaccharide
was indicated that TNF-α was produced 5 h earlier than
NO. To investigate the effect of the purified polysaccharide
on mRNA expression of TNF-α and iNOS, the level of
mRNA was evaluated by RT-PCR. The levels of TNF-α
mRNA was induced at 0.5 h after stimulation, peaked at 3
h. On the other hand, those of iNOS mRNA was induced at
3 h and thereafter maintained the same levels. Furthermore,
DNA binding activity of NF-κB was rapidly increased even
at 0.5h after treatment, and peaked at 2h. When RAW264.7
was stimulated with the purified polysaccharide
simultaneously in the presence of anti-TNF-α antibody,
TNF-α mRNA expression did not affect and that of iNOS
was down-regulated. Taking consideration into these
results, it was ascertained that TNF-α production from
RAW264.7 stimulated with the purified polysaccharide
was enhanced through up-regulating NF-κB, and then the
newly produced TNF-α enhanced NO production with
autocrine pathway. Thus, the purified polysaccharide
possessed the immunomodulating activity and might have
anti-tumor activity.
171 - Synergistic molecular interactions in the
Trichoderma biocontrol system
M. Lorito * , M. Ruocco, D. Piacenti, R. Ciliento, S.
Lanzuise, V. Scala, A. Zoina, F. Scala & S. Woo
Dept. ARBOPAVE- Plant Pathology, University of Naples,
Via Università, 100, 80055 Portici (NA), Italy. - E-mail:
lorito@unina.it
Recent studies have shown that the antagonist mechanism
of Trichoderma spp. is much more complex than expected
because of the numerous factors involved and the variety of
mechanisms activated during the interaction with the host
and the plant. Most of the research at a molecular level has
been focused on the role of fungal cell wall degrading
enzymes and antibiotics in the mycoparasitic relationship
with phytopathogenic fungi. Pathogenicity factors have
been identified among chitinases and glucanases, and from
this, several opportunities have arisen for developing new
biotechnologies for disease control. We have investigated
the interaction between enzymes and antibiotics and found
that Trichoderma applies these factors in synergistic
combinations during attack. Synergism has also been found
among different types of enzymes, and when the encoding
genes are transgenically expressed in plants or other
biocontrol microbes. Also synergisms appears to be the
mode that some chitinases and glucanases interact in
releasing mycoparasitism inducers from the host cell wall
during the early recognition phase. Finally, a high level of
synergism has also been found when Trichoderma or its
antifungal compounds (enzymes or antibiotics) are applied
in combination with Pseudomonas spp. and other
biocontrol agents. We show that functional synergism
between differently acting compounds is critical in
biocontrol and is a key to understand mycoparasitic
mechanisms.
172 - Chitinases and plant induced systemic resistance:
new insights in T. asperellum (T. harzianum 203)
A. Viterbo 1* , M. Shoresh 2 , I. Yedidia 2 , O. Ramot 2 & I.
Chet 1
1 Weizmann Institute, Dept. of Biological Chemistry,
Rehovot, 76100, Israel. - 2 Hebrew University, Otto
Warburg Center, Rehovot, 76100, Israel.
Two main modes of action can be discerned in the
biocontrol mechanism of some Trichoderma species:
mycoparasitism and plant systemic induced resistance. In
order to better understand the role of chitinases in
mycoparasitism of T. asperellum, we have studied
regulation of the expression of the endochitinase chit36 and
the N-acetylglucosaminidases coding for Chit73 and
Chit102 using Northern blots and a promoter-GFP reporter
system. Despite their close sequence similarity, chit73 and
chit102 are differentially regulated under stress conditions
and by chitin degradation products. chit36 expression is upregulated
in vivo during pathogen confrontation. Induced
plant resistance by Trichoderma was studied using a
spatially separated challenge system and real-time PCR.
We could show that the ethylene and jasmonic acid
signaling pathway are triggered in cucumber roots
inoculated with T. asperellum. As the result of this
different PR proteins and antibacterial phenolic compounds
are systemically induced in the leaves of the plant. These
preliminary data provide initial insights at the molecular
level on the Trichoderma-plant interaction.
Book of Abstracts 55