Book of Abstracts (PDF) - International Mycological Association

IMC7 Main Congress Theme V: CELL BIOLOGY AND PHYSIOLOGY Posters
β-guaiacyl ether as a specific method for the measurement
of ligninolytic activity. Secreted enzymes were prepared
from media of carbon-starved, ferulic acid supplemented
cultures of Trametes. Capability to degradation of β-O-4
bond was measured in reaction mixtures containing
enzymes, the dimer substrate, hydrogen peroxide and
ferulic or p-coumaric acid. Reaction products were
analysed by capillary electrophoresis. Presence either
ferulic or p-coumaric acid in reaction mixture resulted in
significant decrease of dimer degradation. Both
hydroxycinnamates are parts of lignocellulosic polymer,
forming bridges between hemicelluloses and lignin, and
both are known as natural antioxidants. When released by
relevant esterases during lignocellulosics degradation, they
stimulates production of ligninolytic enzymes and
simultaneosly diminish enzymatic activities splitting the
ether bond β-O-4. This paradoxical effect deserves further
reasearch. Supported by the EC Contract ICA 2-CT-2000-
10050 and by KBN grant 139/E-SPUB-M-5PR-UE/DZ
280/2000.
1157 - Can wooddecay fungi use chitosan as a N-source
at extreme C/N-ratios?
M.S.C. Nyborg * & S. Rosendahl
University of Copenhagen, Botanical Institute, Dept. of
Mycology, Øster farimagsgade 2 D, 1353 Kbh. K,
Denmark. - E-mail: mathilden@bot.ku.dk
Chitosan has been proposed as an alternative,
environmentally safe wood preservative. In vitro tests of
wood preservatives are often carried out on media with
moderate C/N-ratios in contrast to the high C/N-ratio in
wood. Chitosan contains nitrogen and fungi could therefore
be suspected to use this as an N-source under extreme C/Nratios.
In this study, we investigated the relationship
between the inhibiting effect of chitosan and the C/N-ratio
of the media. The fungi used were Trametes versicolor,
Heterobasidion annosum, Gloeophyllum trabeum and
Oligoporus placenta. The experimental set-up was a
factorial design with 5 concentrations of chitosan and 6
C/N-ratios in a solid caboxymethylcellulose medium. The
growth was measured as colony diameter. In general, the
growth of the fungi was much more affected by chitosan
than by the C/N-ratio. The C/N-ratio had only limited
effect on Trametes versicolor, Heterobasidion annosum
and Gloeophyllum trabeum, whereas Oligoporus placenta
was clearly stressed by high C/N-ratios. However
Oligoporus placenta was also inhibited by the chitosan.
The effect of chitosan was independent of the C/N-ratios,
indicating that wooddecay fungi are not able to use
chitosan as an alternative N-source at extreme C/N-ratios.
1158 - Environmental signals associated to the
transcriptional activation of the mycoparasitism related
gene prb1 in Trichoderma atroviride
V. Olmedo-Monfil * , A. Mendoza-Mendoza, I. Gómez, C.
Cortés & A. Herrera-Estrella
Department of Plant Genetic Engineering, Centro de
Investigación y Estudios Avanzados. Unidad Irapuato,
Apartado Postal 629. 36500, Irapuaro, Gto, Mexico. - Email:
volmedo@ira.cinvestav.mx
Trichoderma atroviride parasites a large variety of
phytopathogenic fungi. This characteristic has allowed its
use as a biological control agent. The production of
hydrolytic enzymes appears to be a key element in the
parasitic process. Among the enzymes released by
Trichoderma, the proteinase Prb1 plays a major role.
Herewith we show that the corresponding gene (prb1) is
subjected to Nitrogen Catabolic Repression. Accordingly,
induction of prb1 transcription by Rhizoctonia solani cell
walls and by osmotic stress requires the release from a
represed condition which is determined by nitrogen
availability. Furthermore, the transcription pattern of the
prb1 gene was not affected when a p38-Hog1 inhibitor was
used. In contrast, a MEK1/2 inhibitor blocked prb1
transcription in response to nitrogen limitation, indicating
that the pathway employed in the nitrogen response
involves proteins similar to p42-p44. Fusions of the prb1
promoter with the gfp reporter gene allowed the detection
of a novel regulatory element and represent the first insight
into relevant sites that control prb1 expression.
1159 - Heavy metal accumulation and distribution in
mycorrhizal and nonmycorrhizal roots of Plantago
lanceolata, AAS and micro-PIXE analysis
E. Orlowska 1 , Sz. Zubek 1 , J. Mesjasz-Przybylowicz 2 , W.
Przybylowicz 2 , A. Jurkiewicz 1 & K. Turnau 1*
1 Institute of Botany, Jagiellonian University, ul. Lubicz 46,
31-512 Krakow, Poland. - 2 Materials Research Group,
iThemba LABS, PO Box 722, Somerset West 7129, South
Africa. - E-mail: ubturnau@kinga.cyf-kr.edu.pl
Mycorrhizal and nonmycorrhizal Plantago lanceolata were
grown for six weeks under greenhouse conditions in rhizoboxes
filled with industrial waste. According to atomic
absorption spectroscopy (AAS) the shoots of plants
inoculated with Glomus spp. contained less Zn and Pb than
nonmycorrhizal ones; their roots did not differ statistically.
Selected nonmycorrhizal and mycorrhizal roots were
studied using proton microscopy accompanied by PIXE
microanalysis. Significant differences in element
distribution were found between investigated roots.
Especially a strong accumulation of Zn within the cortex of
mycorrhizal roots was visible. The present results do not
allow judgements on whether the metals are located
exclusively in fungal structures, or both by the fungus and
the colonised plant cells. In mycorrhizal roots more Zn and
Pb were found within the vascular tissues than in
nonmycorrhizal ones. Therefore, mycorrhiza is not
effective as a filtering mechanism; still, its role in the
transformation of heavy metals into non-toxic compounds
cannot be excluded. According to AAS these compounds
are retained in roots, as a decrease of these elements was
observed in shoots. This could also suggest the presence of
additional mechanisms depending on the plant, which
enable it to cope with metals transferred by the fungus.
Book of Abstracts 351