Book of Abstracts (PDF) - International Mycological Association

IMC7 Main Congress Theme IV: POPULATION DYNAMICS AND ECOLOGY Posters
1010 - Roles of ascospores in the white root rot fungus,
Rosellinia necatrix
H. Nakamura 1* , K. Ikeda 1 , M. Arakawa 2 & N. Matsumoto 1
1 National Institute for Agro-Environmental Sciences, 3-1-3
Kan-non dai, Tsukuba 305-8604, Japan. - 2 Faculty of
Agriculture, Meijo University, 1-501 Shiogamaguchi,
Tempaku-ku, Nagoya 468-8502, Japan. - E-mail:
nakamh@affrc.go.jp
Rosellinia necatrix Prilleux, the ascomycetous white root
rot pathogen, causes destructive damage to numerous
woody and herbaceous plants, especially to fruit trees,
throughout the world. The fungus produces teleomorph
rarely on diseased plants in nature, and the roles of
ascospores in the life cycle remains unclear due
presumably to the scarcity of teleomorph production. In
this study, stromata produced on root fragments were
studied to elucidate the roles of ascospores. Stromata were
produced on 23 out of 47 diseased root samples from
Japanese pear, grapevine and Chloranthus glaber, which
had been placed in a hollow on the ground surface in the
shade of trees and covered with rice straw. Also, stromata
were obtained on mulberry twigs inoculated with two out
of six isolates. Readiness of stroma production was not
related to host plant species, dates of treatment, or the
presence of double-stranded (ds) RNA. In 18 single
ascospore isolates from six stroma samples, mycelial
interactions between isolates from the same samples were
incompatible, and the isolates were pathogenic to Lupinus
luteus with a few exceptions. dsRNAs in vegetative hyphae
of 10 stroma samples were not transferred to single
ascospore isolates. Thus, ascospores in R. necatrix are
effective in extending genetic variation, producing
pathogenic offspring and eliminating infectious factors
such as dsRNA.
1011 - Population dynamic of Pyrenochaeta terrestris on
the basis of cropping patherns and infection percentage
in onion fields
M. Nasr-Esfahani
Plant pests and diseases research Dep., Agricultural
research center, P.o. Box 81785-199, Esfahan, Iran. - Email:
M_nasresfahni@yahoo.com
Studies on population dynamic of the fungus on the basis
of infection, indicated that the cropping patherns having a
significant effects in infection of the fungus. 441 onion
fields were taken into considerations during 1997-98,
where there was five manin cropping patherns including
alfa-alfa (Medicago sativa L. usually for 4-5 years), cereals
(wheat, barley, rice and seldom millet), vegetables (tomato,
bringal, mask-melon, cauliflower, cabbage, etc), orchard
(where the fruit trees were up rooted and became under
cultivation) and onion frequently for the last four years
before to onion. A hundred onion plants were up rooted
near maturity stage and their roots were examined for the
presence of the infection based on infection percentage of
the roots in three scoring scales (>10%, >25% and more
than 25% infection). The higher infection was observed in
frequent onion growing fields, fallowed by alfa-alfa with
36.16 and 27 percent infection respectively, where the
orchard soil had the least infection with 2.83 percent
infection on onion roots. Out of which 12.58, 9.58 and 0.50
percent were in the ranges of more than 25 percent
respectively with a significant effects, where cereals and
vegetables were in a separate group. These results revealed
that the build up of population inoculum is an improtant
factor in natural enivronments, but the more inportant one
is the population potentiality, which can measured
infectionally and/or differentially with a distinct scoring
scales.
1012 - Coprinaceae in wood and straw degradation:
implications for ecology and biotechnological use
M. Navarro-Gonzalez 1 , M. Hoffmann 1 , O. Holdenrieder 2 &
U. Kües 1*
1 Molecular Wood Biotechnology, Institute for Forest
Botany, Georg-August University Goettingen, Buesgenweg
2, D-37077 Goettingen, Germany. - 2 Section of Forest
Pathology & Dendrology. Department of Forest Sciences.
Federal Institute of Technology, Raemistr. 101, CH-8092
Zurich, Switzerland. - E-mail: ukuees@gwdg.de
Coprinaceae have been defined as a family of about 800
species, following morphological and physiological
characteristics such as lamella and spore colour and their
abilities to self-digest upon fruit body maturation. Recent
molecular analysis suggests Coprinaceae are not
monophyletic but comprise four different genera (1).
Coprini are usually saprotrophic on soil or dung of
herbivores. Species growing on decaying wood or plant
debris in soil and a few plant pathogens have also been
described. Here we present an overview on species relating
to wood and straw degradation. Enzymes implicated in
wood and straw degradation (phenol oxidases including
laccases; peroxidases; xylanases) have been described in a
few species. Biotechnological use have been made of C.
cinereus peroxidase (2) and one laccase (3) - genes for at
least six different laccases are known (3,4). It is thought
that at least some of these enzymes link to developmental
processes, for example fruiting body development (C.
congregatus; 5) and spore formation (C. cinereus; 6). Our
experimental work aims at elucidating wood degrading
abilities of various Coprinaceae, at making use of enzymes
in biotechnology and at determining functions of enzymes
in fungal development. (1) Redhead et al. 2001 Taxon
50:203; (2) Kauffmann et al. 1999 J Biotechnol 73:71; (3)
Yaver et al. 1999 AEM 65:4943; (4) Bottoli et al. 1999 J
Microbiol Meth 35:129; (5) Choi et al. 1987 Mycologia
79:166; (6) Vnenchak, Schwalb 1989 Mycol Res 93:546.
Book of Abstracts 305