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Inoculum 56(4) - Mycological Society of America

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MSA ABSTRACTS<br />

Moore, Geromy and Taylor, Josephine*. Department <strong>of</strong> Biology, Stephen F.<br />

Austin State University, Nacogdoches TX 75961, USA. jtaylor@sfasu.edu. Infection<br />

<strong>of</strong> Cuscuta gronovii by Aureobasidium pullulans.<br />

Aureobasidium pullulans was isolated from necrotic stems <strong>of</strong> Cuscuta<br />

gronovii Willd, commonly known as swamp dodder. Conidia from two-week old<br />

cultures <strong>of</strong> A. pullulans were used to inoculate healthy dodder tendrils under<br />

greenhouse conditions. Necrosis was produced within 48 hours, at which time the<br />

fungus had thoroughly colonized the dodder stem surface. Transmission electron<br />

microscopy revealed the presence <strong>of</strong> both intercellular and intracellular hyphae<br />

within cortical cells <strong>of</strong> the dodder stem. A. pullulans holds promise as a potential<br />

mycoherbicide to treat dodder infestations. poster<br />

Morgenstern, Ingo*, Klopman, Shlomit and Hibbett, David S. Department <strong>of</strong> Biology,<br />

Clark University, Worcester MA 01610, USA. imorgenstern@clarku.edu.<br />

Diversity and phylogenetic relationships <strong>of</strong> class II fungal heme peroxidases<br />

in homobasidiomycetes.<br />

Heme containing peroxidases are common enzymes occurring in all living<br />

organisms. Mostly, they are used in response to various kinds <strong>of</strong> oxidative stress,<br />

but in white rot fungi belonging to the homobasidiomycetes they play an important<br />

role in lignin degradation. According to structural and biochemical features<br />

ligninolytic fungal peroxidases are placed in class II <strong>of</strong> the superfamily <strong>of</strong> plant<br />

peroxidases. Manganese peroxidases (MnP), lignin peroxidases (LiP), and the<br />

more recently described versatile peroxidases (VP) are members <strong>of</strong> this class.<br />

Fungi producing a white rot do not necessarily secrete all <strong>of</strong> these enzymes. However,<br />

if a type <strong>of</strong> heme peroxidase is present it usually occurs in a series <strong>of</strong> multiple<br />

is<strong>of</strong>orms. We have performed phylogenetic analyses using complete amino<br />

acid sequences from published sources which reveal that class II fungal peroxidases<br />

share evolutionary roots with class I (peroxidases <strong>of</strong> prokaryotic origin) and<br />

class III (classical plant peroxidases) <strong>of</strong> the superfamily plant peroxidases. We<br />

have also generated partial MnP gene sequences, which we have combined with<br />

the published full-length sequences for phylogenetic analyses focused on evolutionary<br />

relationships within the fungal peroxidases. Finally, we have performed<br />

tree reconciliation analyses between gene trees and species trees to elucidate the<br />

diversity and phylogenetic relationships <strong>of</strong> these enzymes. The results <strong>of</strong> these<br />

analyses indicate that there have been many gene duplications in class II fungal<br />

peroxidases, including ancient and recent events. contributed presentation<br />

Morita, Atsushi* and Tanaka, Chihiro. Laboratory <strong>of</strong> Environmental Mycoscience,<br />

Graduate School <strong>of</strong> Agriculture, Kyoto University, Kyoto, 606-8502,<br />

Japan. poet50@kais.kyoto-u.ac.jp. Identification and characterization <strong>of</strong><br />

NRPS-like gene EmMaa1 in Exserohilum monoceras.<br />

Exserohilum monoceras is a fungal pathogen <strong>of</strong> Echinochloa weed species,<br />

and now used as a bioherbicide for them in Japanese paddy fields. However, as<br />

yet little has known about its virulent factor or pathogenic mechanism. We have<br />

investigated the functions <strong>of</strong> non-ribosomal peptide synthetases (NRPSs) in E.<br />

monoceras, for that some peptide compounds are characterized as host specific<br />

toxins in phylogenically related species (e.g Cochliobolus and Alternaria). Using<br />

PCR with degenerate primers we have obtained several putative NRPS gene fragments<br />

<strong>of</strong> E. monoceras. In this study, we report the cloning and functional analysis<br />

<strong>of</strong> EmMaa1. Sequence analysis <strong>of</strong> EmMaa1 revealed that it was a homolog <strong>of</strong><br />

Maa1 originally identified in Leptosphaeria maculans genome, and also indicated<br />

that EmMaa1 was an NRPS-like gene with single adenylation domain, thiolation<br />

domain but no condensation domain. In L. maculans Maa1 disruptant was<br />

identical to wild type with respect to growth and pathogenicity. Targeted disruption<br />

<strong>of</strong> EmMaa1 also resulted in no phenotypic alteration in pathogenicity between<br />

mutant and wild type. However EmMaa1 disruptant showed relatively<br />

slower growth and more aerial hyphae production than wild type. This suggests<br />

EmMaa1 is not involved in the pathogenicity <strong>of</strong> E. monoceras, but has something<br />

to do with its vegetative growth. poster<br />

Mouriño-Pérez, Rosa R. 1 *, Roberson, Robert W. 2 and Bartnicki-García, Salomón 1 .<br />

1 Department <strong>of</strong> Microbiology and Division <strong>of</strong> Biological Experimentation & Application,<br />

Center for Scientific Research <strong>of</strong> Ensenada (CICESE), Km. 107 Ctra. Tijuana-Ensenada,<br />

Baja California, México, 2 School <strong>of</strong> Life Sciences, Arizona State<br />

University, Tempe, AZ, USA. rmourino@cicese.mx. Dynamics <strong>of</strong> the microtubular<br />

cytoskeleton during growth and branching in Neurospora crassa.<br />

By confocal microscopy, we analyzed microtubule (MT) behavior during<br />

hyphal growth and branching in a Neurospora crassa strain whose microtubules<br />

were GFP-tagged. Images were assembled in space and time for a precise picture<br />

<strong>of</strong> the 3-D organization <strong>of</strong> the microtubular cytoskeleton and a clear view <strong>of</strong> its<br />

dynamics. Cytoplasmic MTs are mainly arranged longitudinally along the hyphal<br />

tube. Straight segments are rare; most MTs show a distinct helical curvature with<br />

a long pitch and a tendency to intertwine with one another to form a loosely braided<br />

network throughout the cytoplasm. This study revealed that the microtubular<br />

cytoskeleton <strong>of</strong> a hypha advances as a unit: as the cell elongates, it moves forward<br />

by bulk flow. Nuclei appeared trapped in the microtubular network and were carried<br />

forward in unison as the hypha elongated. During branching, one or more<br />

MTs became associated with the incipient branch. Branch MTs are continuous<br />

with a set <strong>of</strong> adjacent MTs from the parent hypha. Originally transverse in the incipient<br />

branch, MT orientation turned longitudinal as the branch elongated and the<br />

42 <strong>Inoculum</strong> <strong>56</strong>(4), August 2005<br />

length and number <strong>of</strong> MTs increased. Although a full account <strong>of</strong> the origin <strong>of</strong><br />

branch MTs remains an open question, the recorded evidence indicates both bulk<br />

insertion <strong>of</strong> parent-hypha MTs as well as de novo extension by anterograde polymerization.<br />

The latter conclusion was supported by FRAP studies showing evidence<br />

<strong>of</strong> MT assembly in the growing tip <strong>of</strong> the developing branch. Nuclei entered<br />

the branch entrapped in the advancing network <strong>of</strong> MTs. contributed<br />

presentation<br />

Mozley-Standridge, Sharon* and Porter, David. Department <strong>of</strong> Plant Biology,<br />

University <strong>of</strong> Georgia, Athens, GA 30602, USA. emozley@plantbio.uga.edu.<br />

Chytrid fungi in the “Nowakowskiella” clade (order Chytridiales, phylum<br />

Chytridiomycota): determination <strong>of</strong> generic limits using 18S small and 28S<br />

large ribosomal subunit nuclear gene sequences.<br />

Multiple classification schemes exist for members <strong>of</strong> the Chytridiomycota<br />

based on different uses <strong>of</strong> morphological, developmental, and ultrastructural characters.<br />

Addition <strong>of</strong> molecular characters from multiple genes has provided support<br />

for the most recent order level classification scheme based primarily on ultrastructural<br />

characters. For chytrid fungi in the recently identified<br />

“Nowakowskiella” clade (order Chytridiales), ultrastructure has been sampled for<br />

several genera with few distinguishing differences between genera. On the other<br />

hand, combined analysis <strong>of</strong> 18S and 28S ribosomal genes has provided a better<br />

idea <strong>of</strong> generic limits for members <strong>of</strong> the clade and can be used as a framework<br />

for comparison <strong>of</strong> morphological and developmental characters in a phylogenetic<br />

context. Included in this study are suggestions for taxonomic revision <strong>of</strong> Allochytridium,<br />

Catenochytridium, Cladochytrium, Nowakowskiella, Nephrochytrium,<br />

and Septochytrium. poster<br />

Mueller, Gregory M. Department <strong>of</strong> Botany, The Field Museum, Chicago, IL<br />

60605, USA. gmueller@fieldmuseum.org. Overview <strong>of</strong> fungal biogeography.<br />

Until recently, the prevailing notion was that ancient organisms with easily<br />

dispersed spores like fungi would be broadly distributed with few interesting biogeographic<br />

patterns. There were exceptions, such as the distribution <strong>of</strong> Cytaria<br />

with Noth<strong>of</strong>agus and potential temperate East Asian / Eastern North <strong>America</strong>n<br />

disjuncts. For the most part, distribution patterns were listed only as secondary information<br />

in monographs or discussed with a pathogen’s host distribution. Pairing<br />

studies to implement the biological species concept necessitated sampling<br />

multiple individuals over the entire geographic range for the first time, and the repeated<br />

discovery <strong>of</strong> discrete, genetically isolated populations <strong>of</strong> supposedly cosmopolitan<br />

species sparked an interest in understanding biogeographic patterns <strong>of</strong><br />

fungi. Rigorous testing awaited the development <strong>of</strong> molecular data and the computational<br />

techniques and theory needed to analyze the data. We now know that<br />

many species <strong>of</strong> fungi have discrete distribution ranges, <strong>of</strong>ten concruent with patterns<br />

seen in animals and plants. While much progress has been made, numerous<br />

questions remain, including the importance <strong>of</strong> the role spores play in dispersal, the<br />

constraints or drivers which determine diverse organismal distribution patterns,<br />

and the age-specific information that is provided by distribution patterns for fungal<br />

clades. symposium presentation<br />

Mullaney, Edward J.* and Ullah, Abul H. J. Southern Regional Research Center,<br />

ARS, USDA, New Orleans, LA 70124, USA. emul@srrc.ars.usda.gov. Conservation<br />

<strong>of</strong> an eight-cysteine motif in fungal histidine acid phosphatases.<br />

A survey <strong>of</strong> known amino acid sequence <strong>of</strong> a number <strong>of</strong> fungal histidine<br />

acid phosphatases (HAP) has revealed a conserved eight-cysteine motif (8CM).<br />

Typically, conserved amino acid sequences have been associated with catalytic or<br />

structurally essential components for the functionality <strong>of</strong> a protein. The catalytic<br />

mechanism <strong>of</strong> HAPs is known, and no cysteines are involved in catalysis. Therefore,<br />

the HAP’s 8CM appears to have been conserved because they are involved<br />

in the formation <strong>of</strong> key disulfide bridges. X-ray crystallographic data <strong>of</strong> Aspergillus<br />

nigermyo-inositol hexakisphosphate and a few other fungal HAPs have<br />

revealed that all eight cysteines are components <strong>of</strong> disulfide bridges. While 3-D<br />

molecular models for all fungal HAPs are not available, the unique pattern <strong>of</strong> conservation<br />

supports a similar critical role for these amino acids in all these HAPs<br />

sequences. A different 8CM has recently been reported from a survey <strong>of</strong> plant<br />

databases. Almost 500 different plant polypeptides having various functions all<br />

shared a unique cysteine motif, which like the HAP cysteines has no catalytic<br />

function. Rather, it appears that both the plant and the HAP 8CM have been conserved<br />

to provide the essential tertiary structure <strong>of</strong> the molecule for maintaining<br />

both a functional active site and a substrate-binding domain. poster<br />

Munkacsi, Andrew 1 * and May, Georgiana 2 . 1 Plant Biological Sciences Graduate<br />

Program, University <strong>of</strong> Minnesota St. Paul, MN, USA, 2 Department <strong>of</strong> Ecology,<br />

Evolution and Behavior, University <strong>of</strong> Minnesota, USA. munk0009@umn.edu.<br />

A phylogenetic and population genetic reconstruction <strong>of</strong> Ustilago maydis.<br />

Maize was domesticated in southern Mexico from a teosinte 10,000 years<br />

ago, and exported to the United States 2,000 years ago and to South <strong>America</strong><br />

5,000 years ago. Ustilago maydis only infects maize and the teosintes. We tested<br />

the popular hypothesis that U. maydis originated on a teosinte in Mexico and followed<br />

maize as maize was traded to new locations. We collected DNA sequence<br />

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