March 2008 - Mycological Society of America

2 Las Muros, Rimont, Ariège, F 09420, France. kdhyde@hkucc.hku.hk.
Revision of Pleosporales. We are working on a monograph revising the
Pleosporales by examining the type specimen of each genus and other
collections. We will provide a full description of the type specimens and
illustrate the genera using photographic plates and line drawings. Of the
127 genera in Pleosporales, we have presently examined 56 type specimens
(44%). Most of the type specimens are in good condition. The
other specimens are in the process of being loaned. We are also searching
for fresh material of Pleosporales. We have obtained 93 fresh specimens.
Most of these are from France, including a new genus Amniculicola
lignicola gen et sp. nov. from freshwater. Eight fresh specimens of
type species of Pleosporales genera have so far been obtain. By examining
types and obtaining identical fresh material we can be sure that the
materials we use in molecular studies are correctly identified. Where
necessary we can also designate epitypes using the fresh material as
these specimens also have living isolates. Our further work will be focused
on searching more fresh material of the type species to conduct
systematic phylogenetic analysis with rDNA sequences. We are also
linking the teleomorphs with their anamorphs where possible. Poster
Inderbitzin, Patrik 1 *, Schoch, Conrad 2 and Turgeon, B. Gillian. 11 Cornell
University, Plant Pathology, Ithaca, NY, USA, 2 Oregon State University,
Dept. of Botany and Plant Pathology, Corvallis, OR, USA.
prin@uckac.edu. Exploring the evolutionary origins of T-toxin, the
Cochliobolus heterostrophus polyketide virulence factor implicated
in the Southern Corn Leaf Blight epidemic. The polyketide virulence
factor, T-toxin, is produced by race T of the ascomycete Cochliobolus
heterostrophus, the cause of Southern Corn Leaf Blight. Due to complex
structural features of the locus, Tox1, required for T-toxin production
and the sporadic phylogenetic distribution of the 9 known T-toxin
genes, unraveling the evolutionary history of the genes is not straightforward.
T-toxin genes are distributed at two loci associated with the
breakpoints of a reciprocal translocation and encompass ca. 1.2 Mb of
A+T rich, highly repetitive DNA present in race T, but missing in non-
T-toxin producing race O, and from all other species of Cochliobolus.
Furthermore, the T-toxin genes are not clustered, unlike genes required
for biosynthesis of most fungal polyketides e.g. lovastatin and aflatoxin.
Together, these data suggest that the T-toxin genes may have been acquired
by race T from an unknown source and that, upon integration of
this DNA, a reciprocal translocation occurred, distributing the genes at
two loci. To further investigate evolution of the T-toxin locus, we
screened 117 close and distant relatives for the presence of new ChPKS1
orthologs and found just one. We are currently investigating the origins
of the remaining 8 T-toxin genes from race T. The data obtained so far
do not contradict the horizontal transfer hypothesis, but a vertical origin
cannot be ruled out. Contributed Presentation
Isikhuemhen, O. S.* and Mikiashvili, N. Mushroom Biology & Fungal
Biotechnology Laboratory, SAES, North Carolina A&T State University,
Greensboro, NC 27411, USA. omon@ncat.edu. Lignin, cellulose,
and hemicellulose degrading enzyme production by selected polypores.
Lignocellulose degrading enzymes and biodegradation of wheat
straw by Grifola frondosa, Grifola umbellata and two strains of Polyporus
squamosus (1165 and 456) were investigated. Lignin, cellulose
and hemicellulose degrading enzymes, as well as loss of organic matter
(LOM) were assayed at 16, 30, 44 and 60 days from start of experiment.
Lignin modifying enzymes, laccase, manganese dependent and
manganese independent peroxidise were detected in fungi isolates tested.
Cellulose degrading enzymes detected were carboxymethyl cellulase
and cellobiosidase and hemicellulose degrading enzymes were xylanase,
1,4-α-xylosidase. The two Polyporus strains tested produced
more lignocellulose degrading enzymes than G. frondosa and G. umbellata.
In hemicellulose degradation, Grifola strains produced more
xylosidase than the P. squamosus strains. However, the reverse was the
case with xylanase, for which P. squamosus strains showed activities in
the order of 36% (456) and 10% (1165) higher than G. umbellata. The
highest LOM (36 %) was in P. squamosus (1165), followed by 456 (34
%), G. frondosa (20.4%) and G. umbellata (7.6%). Our results indicate
that higher ligninolytic and cellulolytic enzyme activities resulted in
22 Inoculum 59(2), March 2008
higher levels of degradation (LOM) in wheat straw substrate. Optimization
of wheat straw degradation under solid-state fermentation is
under investigation. Poster
Isikhuemhen, O.S. 1 *, Sisson, J. 2 , Liedl, B.E. 2 and Chatfield, J.M. 2
1 Mushroom Biology and Fungal Biotechnology Laboratory, School of
Agriculture & Environmental Sciences, North Carolina A&T State
University, Greensboro, NC 27411, USA, 2 Agricultural and Environmental
Research Station, Gus R. Douglass Land-Grant Institute, West
Virginia State University, Institute, WV 25112, USA. omon@ncat.edu.
Cultivation of Agrocybe aegerita on solid waste from thermophilic
anaerobic digestion of poultry litter. Solid waste (SW) effluent from
thermophillic anaerobic digestion of poultry litter was tested as substrate
for the cultivation of Agrocybe aegerita (black poplar mushroom).
Substrate combinations tested contained 0, 10, 25, 50 75 and
100% SW. Ten replicates of each substrate combination, after sterilization
at 121 °C for 3 h, was inoculated with spawn from the test fungus,
incubated at 25 °C and transferred to the fruiting house upon pinning.
Significant differences existed between substrate combinations
evaluated by fresh and dry weight yields. Substrate combinations with
100% and 75% SW appeared to be the best, producing mean fresh
weight yields of 321.75 g and 308.94 g and mean dry weights of 31.79
g and 28.26 g, respectively. They out performed the positive control,
which had mean fresh and dry weights of 278.23 g and 22.65 g. In general,
any substrate combination that had 50% or more SW out performed
the positive control. Results indicate that solid waste effluent
can be used for A. aegerita cultivation. A pilot study for commercial
application of SW in the cultivation of A. aegerita is ongoing in our laboratories.
Poster
Iturriaga, Teresa 1 *, Hawksworth, David L. 2 and Crane, J. Leland. 31 Departamento
Biología de Organismos, Universidad Simón Bolívar,
Apartado 89000 Sartenejas, Baruta, Edo. Miranda, Venezuela, 2 Departamento
de Biología Vegetal II, Facultad de Farmacia, Universidad
Complutense, Plaza Ramón y Cajal, Ciudad Universitaria, Madrid
28040, Spain, 3 607 E Peabody Natural Resources Building, Illinois
Natural History Survey, Champaign, IL 61829, USA. titurri@usb.ve.
A new lichenicolous fungus on Leptogium from Venezuela. A new
species of Sporidesmium is described from the decaying thallus of an
unidentified Leptogium species growing on unidentified tree bark from
the Guaramacal National Park in Boconó, Táchira State, in western
Venezuela. This is only the second lichenicolous species to be described
under this generic name, and differences from that species and
similar species in Sporidesmium s. lat are discussed. A more precise
generic placement will have to await a molecularly based taxonomy of
the genus. The original material comes from a mycologically little-explored
region of the country, and brief information on previous mycological
(including lichenological) studies in the area is provided for the
first time in English. A new combination of another species under the
same genus Sporidesmium is also made. Poster
Izzo, Antonio D.* and Mazzola, M. USDA Agricultural Research ServiceTree
Fruit Laboratory,1104 N. Western Ave.,Wenatchee, WA
98801, USA. Izzo@tfrl.ars.usda.gov. Assessing the utility of a taxonomic
macroarray for monitoring fungal community development
in soils exhibiting suppression of root disease. A broad range of fungi
can impact plant health either directly or indirectly, and the interactions
that lead to the development of a healthy or diseased plant are very
complex. We tested the viability of a membrane-based PCR product
taxonomic macroarray as a means to monitor the transformation of soil
fungal communities following the incorporation of Brassica seed meals
(BSM) known to have differential impact on members of the pathogen
complex that incites apple replant disease (ARD). Tests with probes of
known composition demonstrated that the approach is capable of distinguishing
DNA sequences differing by amounts that generally translate
into sub-generic lineages. Tests using mixed-community probes
constructed from soils amended with either of two BSMs indicated that
Trichoderma species were initially preferentially dominant in amended
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