Inoculum 56(4) - Mycological Society of America

Barrett, Luke G., Thrall, Peter H., Burdon, Jeremy J. and van der Merwe, Marlien
M.* Centre for Plant Biodiversity Research, CSIRO – Plant Industry, GPO Box
1600, Canberra ACT 2601, Australia. marlien.vandermerwe@csiro.au Pancontinental
patterns of genetic variation in the rust fungus Melampsora lini.
The Linum marginale-Melampsora lini plant-pathogen interaction is endemic
to Australia and has been a focus of epidemiological and coevolutionary
studies for more than a decade. Considerable variation for both host resistance and
pathogen virulence has been shown at a range of spatial scales from the local to
the continental. Here we report on a study using AFLP and SSR markers to examine
pancontinental patterns of genetic variation in 102 clonal lines of M. lini
representing 35 populations. Molecular marker genotypes partition all of the isolates
into two major lineages, and in combination with subsequent sequencing of
beta-tubulin and elongation factor genes suggest a possible hybrid origin for one
of the lineages. Subsequent comparison with data on phenotypic variation for virulence
in a subset of these isolates also demonstrates striking differences between
the two lineages in terms of pathogenicity on the host L. marginale. Molecular genetic
variation within the lineages was very limited, and within populations both
AFLP and SSR markers regularly failed to distinguish among several lines with
different pathotypes. These results are important for developing an understanding
of how pathogen virulence might evolve within natural populations. poster
Barrow, Jerry R.*, Lucero, Mary L., Osuna-Avila, Pedro, Reyes-Vera, Isaac and
Aaltonen, Ronald E. USDA-ARS Jornada Experimental Range, Las Cruces, NM
88003, USA. jbarrow@nmsu.edu. Hybrid vigor, structural modification and
enhanced plant performance induced by symbiotic fungi-plant interactions.
Hybrid vigor, structural modification and enhanced plant performance induced
by symbiotic fungi-plant interactions. Communities of symbiotic fungi are
intrinsically integrated with single cells, tissues and organs of desert plants. They
are obligately associated with living tissues and generally cannot be isolated and
cultured separately. Symbiotic fungi indigenous to native desert plants were transferred,
using cell culture methods, to non-host plants and reciprocally transferred
between native grasses. Crop and native plants, with recipient fungi have astounding
and increased levels of vigor. Up to five-fold increases in root and shoot
biomass and substantial morphological changes and reproductive potential were
obtained. Enhanced chlorophyll and phosphorous content were common responses.
Once integrated, fungi were intimately interfaced with the plasmalema
of the new host plant and were ecto-cytoplasmically inherited. This technology
accesses a previously unexplored source of genetic variability within native
ecosystems with the potential of immediate transfer to improve tolerance of native
and crop plants to stress, disease and pests. Symbiotic fungal transfers provides
a powerful alternative for genetic improvement of plants. contributed presentation
Bartnicki-García, Salomón. Microbiology Dept., CICESE, Ensenada, Baja California,
22860, México. bartnick@cicese.mx. Introductory remarks: Current
perspectives in hyphal morphogenesis.
Hyphal morphogenesis is clearly the most basic developmental process in
mycology. The origin of the fungal kingdom could be traced to the “invention” of
hyphal morphogenesis, i.e. the ability of a cell to form long tubular walls by tip
growth. Not surprisingly, over the years, fungal biologists have become increasingly
interested in elucidating the cellular and molecular basis of hyphal morphogenesis.
The problem revolves basically about understanding the mechanism(s)
responsible for polarized growth of the cell wall. A number of structural and molecular
players have been identified but the mechanism cannot be attributed to a
single gene or protein. Polarized secretion probably requires a specific concerted
action between cytoskeleton and secretory vesicles to produce a pattern of vesicle
discharge that would generate cells with a profile described by the hyphoid equation:
y = x cot (xV/N). This symposium on Advances in Fungal Morphogenesis
will cover developments in different fronts: a new way of probing the surface
properties of the hyphal wall (S. Kaminskyj), assessing the importance of protein
glycosylation in the maintenance of hyphal growth (B. Shaw), and analyzing the
role of the Spitzenkörper in apical growth (M. Riquelme). symposium presentation
Baucom, Deana L.*, Bruhn, Johann N. and Mihail, Jeanne D. Division of Plant
Sciences, University of Missouri, Columbia MO 65211, USA. dlba3c@mizzou.edu.
Armillaria species involved in Missouri Ozark forest decline.
In the Missouri Ozark Mountains, Armillaria spp. contribute to oak decline.
To investigate the distributions and roles of Armillaria spp., 142 isolates collected
in 2002 from 40 plots were identified. Amplification of IGS1 followed by restriction
with AluI identified 121 isolates as A. mellea (52 %), A. gallica (38 %),
and A. tabescens (10 %). Two new RFLP patterns were found to represent 41 %
of A. mellea and 17 % of A. gallica isolates. Isolates yielding these patterns are
currently being characterized by sequence analysis of IGS1. Major hosts were
dogwood (44 %), red oaks (18 %), and white oaks (7 %). Armillaria mellea predominated
on both white and red oaks; A. mellea and A. gallica occurred equally
on dogwood. Recently killed trees provided 28 % of study isolates. Armillaria
was almost universally present on recently killed trees. Red oaks, dogwood, and
white oaks provided 38 %, 32 %, and 10 % of recent mortality isolates, respectively.
Nearly all recent oak mortality yielded A. mellea. Recent dogwood mor-
MSA ABSTRACTS
tality yielded A. gallica (54 %) more frequently than A. mellea (38 %). Ozark oak
decline affects red oaks and dogwoods most heavily. The Armillaria sp. which
most commonly contributed to oak mortality on our plots in 2002 was A. mellea,
though A. gallica was more commonly recovered from recent dogwood mortality.
We found little evidence of mortality caused by A. tabescens. poster
Beeson, Esther 1 , Beltz, Shannon 2 , Klich, Maren 2 and Bennett, Joan W. 1 * 1 Tulane
University, New Orleans, LA, USA, 2 Southern Regional Resource Center, New
Orleans, LA, USA. ebeeson1@cox.net. Sclerotial production in Aspergillus
flavus varies with temperature and nitrogen source.
Twenty strains of Aspergillus flavus from the culture collection of the
Southern Regional Research Laboratory, New Orleans, LA, were grown on defined
and complex media at 25 o C and 37 o C for one week. Colonies were
screened for sclerotial production as well as other colony characters including production
of conidia, floccose hyphae, and mycelial pigment. When grown on complex
media with yeast extract as the nitrogen source, 9 of the strains produced
sclerotia at 25 o C and 11 produced sclerotia at 37 o C. When grown on a defined
medium with nitrate as nitrogen source, 8 of the strains produced sclerotia at 37
o C and 5 produced sclerotia at 25 o C. When ammonium was used as the nitrogen
source, only one strain produced sclerotia at 37 o C and there was no sclerotial production
at 25 o C. Sporulation was sparse or absent for all strains grown on ammonium
at 37 o C. When microarrays of the A. flavus genome become available,
these data will be useful in designing conditions for RNA isolation in order to
probe the genes involved in sclerotial formation. poster
Bennett, Chandalin 1 *, Newcombe, George 1 and Aime, M. Catherine 2 . 1 Department
of Forest Resources, University of Idaho, Moscow, Idaho 83844, USA,
2 USDA ARS Systematic Botany and Mycology Lab, Beltsville, Maryland 20705,
USA. benn4449@uidaho.edu. Regional studies of Melampsora on Salix in the
Pacific Northwest.
Melampsora epitea Thuem. is a species complex that represents all willow
rusts in N. America. To better understand how much host-specialization and genetic
diversity exists in the Pacific Northwest (PNW), a large-scale host-range inoculation
study was performed along with ITS sequencing, morphological analysis,
and a two-year field survey. Distinct host-specificity was shown for three
different Melampsora isolates inoculated on nearly equal sets of 440 willows.
Less than 20 percent of the plants in each experiment were susceptible to the inoculum
and greater than 15 percent of those showed some signs of resistance. The
genetic sequencing resulted in four distinct clades, the largest of which likely represents
a complex in this region. The other three clades were strongly divergent
from the complex. There was up to three genetically distinct rusts present in a
given geographic location and four or more genetically distinct rusts on a given
Salix sp. There was found at most two distinct rusts on the same species from the
same population. It’s evident that willow rusts are incredibly diverse in the PNW.
Every experimental inoculum was specialized in its host range and the genetic diversity
was spread across four unique and highly divergent clades. symposium
presentation
Bennett, Joan W. Tulane University, New Orleans, LA 70118, USA.
jbennett@tulane.edu. Industrial mycology: from Takamine’s diastase to
TIGR’s database.
Industrial mycology has its roots in numerous food fermentations that were
developed early in human history. Of these, the Japanese koji process, utilizing
Aspergillus oryzae , is of particular interest because the first microbial enzyme
ever patented was a secreted diastase (amylase) isolated from A. oryzae by Dr. Jokichi
Takamine, a Japanese chemist working in the U.S.A during the late nineteenth
century. In the first half of the twentieth century, several filamentous fungi
were harnessed for the production of additional commercial enzymes and for organic
acids. Although the discovery of penicillin and the subsequent golden age
of antibiotics transformed fermentation technology, the molecular biology of industrial
molds lagged behind that of model species. Now, in the twenty-first century,
genomic research has ushered in a new era of understanding. Genome projects
for several Aspergillus species are completed or underway, revealing new
insights into secondary metabolism, carbon and nitrogen regulation, and other genetic
control mechanisms. aymposium presentation
Berbee, Mary L. 1 *, James, Tim Y. 2 , Longcore, Joyce E. 3 , Stajich, Jason 4 and Vilgalys,
Rytas J. 2 . 1 Dept. of Botany, University of British Columbia, V6T 1Z4
Canada, 2 Dept. of Biology, Duke University, Durham, NC 27708 USA, 3 Biological
Sciences, University of Maine, Orono, ME 04469-5722 USA, 4 Dept. of Molecular
Genetics and Microbiology, Duke University, Durham, NC 27708, USA.
berbee@interchange.ubc.ca. What makes a fungus? Fungal-specific genes
from EST libraries of the basal fungi Batrachochytrium dendrobatidis and
Mortierella verticillata.
The Chytridiomycota and Zygomycota include ancient fungal lineages that
may have originated hundreds of millions of years before plants invaded land. We
looked for shared genes that distinguish the fungi from other kingdoms through
comparison of expressed sequence tag (EST) libraries, from a chytrid, Batrachochytrium
dendrobatidis (1588 ESTs, average length, 572 nucleotides) and
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