Inoculum 63(3) - Mycological Society of America

Trichomycetes (gut fungi) are obligate symbionts of various arthropods
and have been found in marine, freshwater and terrestrial habitats on every continent
except Antarctica. Minimally, gut fungi associate commensally with their immature
aquatic hosts (including black flies, mayflies, stoneflies, isopods, and others)
attaching to the chitinous lining of the mid- or hindgut, although relationships
may shift depending on the situation. Both the geographic distribution and the biodiversity
of gut fungi are vastly underestimated. Idaho is no exception, as it presents
many opportunities for discovery in unique habitats, including the sagebrush
steppe. Fourteen locations in remote forest streams of Idaho were surveyed for
macroinvertebrates, which were immediately preserved in 95% ethanol upon collection.
Inspection of fixed specimens revealed gut fungi were occasionally protruding
beyond the anus of the host. Specimens were rehydrated, dissected, slide
mounted and those vouchers of gut fungi were used for identification. Hosts included
black flies, mayflies and a few stoneflies. Gut fungi are more typically dissected
from living hosts. These specimens, fixed in the field, presented both challenges
and rewards. Whereas some fungi naturally extend beyond the anus at
maturity, such extension in black fly larvae is not well known. Interestingly, a new
species of Genistellospora, which has unusually large tricho- and zygospores, and
is being described from a separate, less remote sampling location, was also observed
in many of the black fly samples. We suggest that examination of fixed
specimens may present similar opportunities for discovery. Additionally, with
these data collected from fixed specimens, it is clear that these and similar other
habitats in Idaho provide a healthy repository and diversity of trichomycetes.
Richards, Thomas A. Dept. of Zoology. DC1 406C, The Natural History Museum,
Cromwell Road, London, SW7 5BD, United Kingdom. Horizontal gene
transfer and public goods games in fungi and fungi-like organisms
Horizontal gene transfer (HGT) is the transmission of genetic material between
organisms, specifically across species boundaries. A growing body of data
suggests that fungi and fungal-like protists have gained genes by HGT. This is an
exciting result because fungi at first glance represent the most recalcitrant of all
organisms to gene transfer, possessing robust cell walls and having lost
phagotrophic capacities because they feed exclusively by osmotrophy. Using phylogenetic
methods we investigate the role HGT has played in the evolution of
fungi and fungal-like protists, including HGT between plants and fungi. This
work demonstrates that HGT has actually played a role in shaping osmotrophic
phenotypes and furthermore has been important for the evolution of plant parasitic
mechanisms in the oomycetes. I then use this data to argue that HGT has also
shaped public goods games, an important factor in the evolution of osmotrophic
eukaryotes. Together this data suggests HGT in osmotrophic eukaryotes, although
relatively rare compared to prokaryotes, seems to be an important factor for shaping
the evolution of biological functions in these groups.
Riley, Rohan 1 , Alexander Idnurm 2 , Philippe Charron 1 , Yolande Dalpé 3 , and
Nicolas Corradi 1 . 1 Canadian Institute for Advanced Research, Department of Biology,
2
University of Ottawa, 30 Marie Curie Priv. Ottawa ON Canada K1N 6N5,
School of Biological Sciences 5007 Rockhill Road University of Missouri-
Kansas City Kansas City, MO 64110, USA, 3 Eastern Cereal and Oilseed Research
Center, 960 Carling Ave. Ottawa, Ontario K1A 0C6. Searching for clues
of sexual reporoduction in the genomes of arbuscular mycorrhizal fungi
Arbuscular Mycorrhizal Fungi (AMF) represent an ecologically important
and evolutionary intriguing group of land plant symbionts that have been long
regarded as an ancient asexual lineage. However, the recent acquisition of large
sequence datasets has revealed the presence of an alternative scenario for their
supposed long evolutionary clonal history; including the presence of cryptic sexuality.
Here we report the identification of many AMF genes that are commonly
linked with the presence of sex in many fungi across the genome of different
strains of Glomus. These include homologues of MATA_HMG proteins, which to
our surprise were found to be extremely diverse in both number and sequence
variant. This elevated diversity is unmatched by any other known fungal species,
and preliminary evidence suggests that some of these loci might be involved in
partner recognition in these ecologically important organisms.
Rivas Plata, Eimy, François Lutzoni, Orvo Vitikainen, Trevor Goward, Emmanuel
Sérusiaux, Nicolas Magain, and Jolanta Miadlikowska. Department of Biology,
Duke University. 130 Science Drive, Durham, NC 27708-0338. Cophylogenetic
study of the lichen-forming fungus Peltigera and its cyanobiont
Nostoc at an intercontinental spatial scale
The Peltigera aphthosa and P. leucophlebia species complexes are classified
within two sections, Peltidea and Chloropeltigera, respectively. These sections
include mostly tripartite lichens associated with a green alga (Coccomyxa) as the
primary photobiont (in the thallus) and a cyanobacterium (Nostoc) as the secondary
photobiont (in the external cephalodia). Only two species, P. malacea and P.
frippii, both from section Peltidea, are bipartite with Nostoc as the only photobiont.
Members of both sections are restricted to the coldest regions of the northern
hemisphere with a peak of species richness in boreal forests. Although P. aph-
40 Inoculum 63(3), June 2012
thosa and P. leucophlebia are morphologically similar, to the point of being difficult
to distinguish phenotypically, genetically they have diverged extensively
with both clades recovered as paraphyletic but never well supported by bootstrap
analyses. The phenotypical variation in both clades has triggered the description
of several species, such as P. britannica, P. chionophila, P. latiloba, and P. nigripunctata.
Using sequence data of the internal transcribed spacer (ITS) and two
protein-coding genes (beta-tubulin and RPB1), we inferred phylogenetic relationships
for the fungal partner of lichen thalli sampled from North America, Europe,
and Asia. Our phylogenies partially support existing species but also suggest a
more complex taxonomic structure that requires a reassessment of current species
delimitations in these sections. In parallel, we generated a phylogeny for Nostoc
from the same thalli using the rbcLx locus, and found a pattern of associations between
clades of lichen mycobionts and Nostoc photobionts. In particular, samples
of P. malacea, regardless of their geographic origin, appear to be associated with
a unique clade of Nostoc, absent in other species, indicating a mycobiont-photobiont
cospeciation event during their coevolution. This rare case of cospeciation
could result from a secondary acquisition of the bipartite state, following a transition
to a tri-partite state in that section.
Roberson, Robert W. School of Life Sciences, Arizona State University, Tempe,
AZ 85287. The structure of the hyphal apex: Spitzenkörper or not?
The defining feature of filamentous fungi is the hypha. Hyphal growth has
aided the Fungi to successfully utilize a wide range of ecological habitats and develop
multiple lifestyles. Cellular and molecular studies of hyphal growth have
placed great emphasis on the Spitzenkörper (Spk). The Spk is a dense, roughly
spheroidal cluster of vesicles, cytoskeletal components and signaling proteins
found at the tips of most growing hyphae. It plays crucial roles in optimizing hyphal
extension rates and in determining patterns of growth and morphogenesis by
acting as a dynamic organizing center in the reception of secretory vesicles and
orchestrating their delivery to the apical membrane. The Spk appears to have
evolved only in filamentous fungi where it is present in all members of the Basidiomycota
and Ascomycota studied thus far. Interestingly, a structural equivalent
of the Spk is not common or has not been observed in hyphae of the zygomycete
fungi (e.g., Mucoromycotina), or many the other relatively early
diverging lineages. As notable exceptions to this, Spk have been identified in hyphae
of Basidiobolus sp. (a zygomycete of uncertain phylogeny) and Allomyces
macrogynus (Blastocladiomycota). In fungi that lack a recognizable Spk, vesicle
clusters are often present in the hyphal apex. Although the arrangement of these
vesicles is less organized and complex, there are characteristic patterns that are
recognized. For example, in Rhizopus species, and other members of the Mucoromycotina,
a thin crescent-shaped band of closely packed vesicles is present
just beneath the apical plasma membrane. Although there have been great advances
in understanding the biology and distribution of the Spk, profound questions
remain. In this presentation, light and electron microscopy data will used to
review cytoplasmic features of the hyphal apex from diverse fungal groups in
hopes to better understand hyphal cell biology and fungal phylogeny.
Robert, Vincent, Joost Stalpers, and Pedro W Crous. CBS-KNAW, Fungal Biodiversity
Center, Uppsalalaan 8, 3534CT Utrecht, The Netherlands. Nomenclatural
databases as working tools for taxonomists: opportunities and challenges
During the 18th IBC held in Melbourne, important decisions were made
to adapt the CODE to accommodate novel developments. One of them was to enforce
registration in online repositories. This will guarantee easy access to newly
published taxa and associated data. A number of issues remain to be addressed: 1.
possibility of multiple repositories that could act as official registrars has major
implications. Presently Mycobank (IMA) and Index Fungorum (CABI) are the
only repositories, but more might emerge in the future; 2. coexistence of several
repositories necessitates heavy synchronization to reach the desired aims. However,
no collaboration rules are imposed; 3. decisions of the NCF are needed with
regards to the data that have to be deposited (minimum and extended datasets); 4.
future scientific developments will require regular adaptations of the system (e.g.
environmental sampling, genomic data), with cost implications for repositories; 5.
access to type information of taxa should be available and unequivocal to allow
proper taxonomic revisions, especially in the light of one fungus one name; 6. registration
of species data should be regulated, especially concerning types (epitype,
neotype, lectotype) and barcodes; 7. updates from and relations with journals will
have to be clearly established in order to prevent differences between deposits and
publications; 8. taxonomic data are not always up to date and finding experienced
curators willing to spend time on maintaining taxonomic databases is a challenge
that should not be underestimated; 9. high availability of the system has to be ensured
and no serious down-time is acceptable; 10. continuous and professional
services will have cost implications with regard to both hard- and software. Such
questions will have to be addressed and solved by the mycological community before
January 1, 2013.
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