Book of Abstracts (PDF) - International Mycological Association

IMC7 Main Congress Theme IV: POPULATION DYNAMICS AND ECOLOGY Posters
1046 - Structure of mycobiota and organic matter
decomposition in undisturbed biogeocenoses of the
southern taiga
V.A. Terekhova
Institute of Soil Science, Lomonosov Moscow State
University and Russian Academy of Sciences, Vorob'evy
Gory, Moscow, 119899, Russia. - E-mail: vat@soil.msu.ru
The structural and functional peculiarities of soil
microscopic fungi in typical biogeocenoses of the southern
taiga have been characterised. Mycological analysis has
been carried out in the Central Forest State Biosphere
Reserve (CFSBR, Tver oblast, Russia). The information on
taxonomic diversity of mycobiota has been obtained using
the plating method and description of microscopic fungi
species from different plant material, layers of litter and
soil profile horizons in sphagnum spruce forest, bilberry
spruce forest, wood sorrel-nemoral spruce forest, nemoral
spruce forest, black alder grassy-swampy spruce forest.
The soils of biogeocenoses differ significantly in total
reserves of the organic carbon, rate of organic matter
decomposition. The data obtained show high fungal
diversity (Shannon index) in all biogeocenoses, but
seasonal changes in this index are much greater than those
related to the substrate type. The increasing of the rate of
organic matter mineralization and fungal diversity have
been observed only under optimal temperature and water
conditions. We have tried to estimate the role of organic
matter composition, and interspecies relations on the
destructive activity of fungi in model laboratory
experiments. Using cross introduction it has been shown
quite high adaptation of fungi community to the 'native'
decomposed substrate. The research has been supported by
Russian Foundation for Basic Research grant 02-04-48870.
1047 - Nematode-trapping fungi in Victoria Land
(Continental Antarctica)
S. Tosi * , G. Caretta & G. Del Frate
Dipartimento di Ecologia del Territorio e degli Ambienti
Terrestri, Sezione di Micologia, Università degli Studi di
Pavia, via S. Epifanio, 14, 27100, Pavia, Italy. - E-mail:
stosi@et.unipv.it
Nematode-trapping fungi have a world wide distribution.
They were also found in Antarctica. In the present work
nematode-trapping fungi isolated in Victoria Land
(Continental Antarctica) are reported. Fortythree samples
of soil, mosses and ornithogenic materials were collected
during 1987-1999. The investigated area ranges from 74°S
to 76°S and 162°E to 165°E. Nematode-trapping fungi
were isolated by means of sprinkled-plate technique. A
suspension of the nematode Caenorhabditis elegans was
added as a bait. Predaceous hyphomycetes were isolated
from twelve samples. Thirty strains of Arthrobotrys spp.
and one strain of Nematoctonus were isolated and
identified. All Arthrobotrys strains were morphologically
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Book of Abstracts
similar; differences were noted in the general features of
the colony (colours, zonations). They are able to capture
namatodes by means of adhesive nets. The strain of
Nematoctonus is the first record for Maritime and
Continental Antarctica. It is characterized by the presence
of clamp connections on its hyphae, typical of many
heterocaryotic Basidiomycota. It produces adhesive
trapping devices formed by a secretory cell with a
characteristic hour-glass shape. The results here reported,
show that nemade-trapping fungi are abundant in
Continental Antarctica, above all in the moss where there
are nematodes and other small organisms. On the base of
their massive presence and high grade of specialization,
they can be considered indigenous fungi of the Antarctica.
1048 - In vitro mycorrhization of Cistus incanus
seedlings by Tuber melanosporum mycelium
Y. Ventura 1* , V. Kagan Zur 1 , A. Bustan 1 , D. Mills 1 & N.
Roth-Bejerano 2
1 Ben Gurion University of the Negev, Institutes for Applied
Research, P.O. Box 653, Beer Sheva 84105, Israel. - 2 Ben
Gurion University of the Negev, Department of Life
Sciences, P.O. Box 653, Beer Sheva 84105, Israel. - Email:
yventura@bgumail.bgu.ac.il
Establishment of mycorrhizal associations in vitro between
Cistus incanus and Tuber melanosporum strain 1015 was
studied. Cistus incanus, a Mediterranean flowering plant
(Cistaceae), is a known symbiont of the black truffle. It can
easily be germinated and rooted in vitro. Three growth
media were evaluated for plant development, fungal
growth, and mycorrhization: (i) N5, an MS medium
containing one fifth the nitrogen content of the standard
version, (ii) M, a minimal medium developed for in vitro
mycorrhization of VAM, and (iii) half-strength Hoagland
solution. All media were solidified with 0.8% agar. No
significant differences were found between the media in
respect to plant development (height, number of nodes and
dry weight). The tuber mycelium grew vigorously on
medium M, while on half-strength Hoagland and N5 its
growth was very significantly reduced (by 62.5% and
84.6%, respectively). The incidence of Hartig net
establishment was close to 100% on medium M, versus
10% and zero on half-strength Hoagland and medium N5,
respectively. Direct irradiation with light as low as 25 µmol
m -2 sec -1 strongly inhibited T. melanosporum mycelium
growth and mycorrhization failed to occur, whereas diffuse
light showed no effect on fungal development and enabled
mycorrhiza formation. It appears that in vitro growth of
Tuber mycelium is affected by the nature of the medium
and by light intensity and correlates with mycorrhization
degree.