1985 - Mycological Society of America

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B. E. TUCKER. Dept. of Plant Pathology, N.Y. State Agr. Exp. Sta.. Geneva NY 14456. The Nucleus-Associated Organelle of Macrobiotophthora vermicola, a nematophagous Entomophthorales. The morphology of the nucleus-associated organelle is an important character for current attempts to elucidate the phylogenetic relationships within the order Entomophthorales (Zygomycetes). To date, only five members have been examined, representing three families, revealing four different morphologies in NAO ultrastructure. This poster reports the ultrastructural morphology of the NAO of Macrobiotophthora vermicola, which in conventional fixation appears as a simple hollow cylinder measuring 170 x 90 nm with the internal channel measuring 60 nm in diamter. The intranuclear component of the NAO consists of electron opaque material occluding the nuclear pores. Intranuclear spindle microtubules emanate directly from the NAO-INC. The NAO of 5. vermicola is morphologically most similar to those observed in Basidiobolus ranarum, and are significantly smaller and lack the fibrillar taillhandle that is found in Erynia neoaphidis and Strongwellsea magna. G.A. Tuttle and J.P. Jones. Dept. Plant Pathology and Crop Physiology, Louisiana Agricultural Experiment Station. Louisiana State University Agricultural Center, Baton Rouge. LA 70803. Cultural and cytological studies of the Hysteriales. Members of the Hysteriales (Loculoascomycetidae) have been collected from the Gulf Coast area of the U.S., mainly southern Louisiana, for the past two years. Commonly collected orgainsms include Rhytidhysterium -- rufulum. Glonium stellatum, Gloniopsis praelonga, g. curvata, Hysterographium & and Hysterium insidens. Cultural studies have been initiated to attem~t to produce the anamorphs of these organinsms. S'ingle ascospore cultures were established, when possible, on potato dextrose agar or corn meal agar amended with two percent glycerin. The anamorph of G. stellatum (Sphaeronaema byssoideum Lohman ?) could be induced to form when cultures were grown in continuous light but cultures grown in continuous darkness failed to fruit. Cytological studies have been conducted with Glonium stellatum and Gloniopsis sp. Ascus development in these organisms is similar to that reported for other ascomycetes. Crozier formation is followed by karyogamy, meiosis and mitosis, resulting in eight uninucleate ascospores. In g. stellatum one additional mitotic division occurs in the ascospore followed by septun formation, resulting in a two-celled ascospore with one nucleus per cell. In Gloniopsis sp. repeated mitotic divisions with concomitant septum formation in the ascospore results in a muriform hyaline spore. Ull rich, R. C., see Chase, T. E. B. VILGALYS, J. L- JOHNSON, and 0. K. MILLER, JR. Departments of Biology and Anaerobic Microbiology, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061. Preliminary characterization of DNA' s from Col lvbia species. Nucleic acid studies involving DNA homology can provide valuable information for fungal systematics. We have characterized several fungal DNA' s isolated from species of ollvbia. Collvbia drvoohil* and c. bubsul~hurea are two closely related, yet intersterile, species common in North America. Both species possess DNA with a base composition of 45% G+C, a relatively low value for Basidiomycetes. Methods for isolation of whole-cell DNA will be presented. The significance of DNA homology to systematics of Collvbia will be discussed. p. VILGALYS and 0. K. MILLER, JR. Dept. of Biology, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061. Evolutionary systematics of Collvbia ~rvoohila . The Collvbia glrvo~hila complex consfsts of at least six intersterile groups worldwide. Mating compatibility within each group is regulated by bifactorial incompatibility with multiple alleles. In addition, crosses within one group show heterogenic incompatibility between geographically separated populations. Nuclear migration is reduced or absent in all groups examined. Europe and North America each contain four intersterile groups. Within either continent, different groups can be distinguished by one to several reliable morphological features. Groups existing sympatrically thus behave as good biological and taxonomic species. Three of the European groups are each intercompatible with one of three groups from North America, suggesting conspecificity. Basidiocarps from intercompatible allopatric populations, however, are morphologically dissimillar. Electrophoretic evidence indicates that these allopatric populations are genetically divergent at a number of isozyme loci. Studies of i sozyme inheritance in laboratory synthesized dikaryons also suggest that divergent populations of the same group show differential expression of isozyme loci. Mating compatibility between allopatric populations may therefore not be a good criterion of conspecificity. A geographic component to genetic variation in the drvoohile group is consfstent with allopatric models of evolution. The significance of the results to fungal systematics and evolution wi 11 be discussed. H.S. VISHNIAC. Dept. Botany and Microbiology, Oklahoma State University, Stillwater OK 74078. Ribosomal RNA homologies in the definition of basidiobl astomycete taxa. The dogma of molecular phylogeny states that base changes in rRNA occur, on average, at constant rates, so that differences numerous enough to represent an average rate are proportional to evolutionary distance The 5s rRNA sequence comparisons of Walker and Doolittle and of Huysmans and co-workers indicate an early divergence of Teliomycetes from other fungal groups, separating those heterobasidiomycetous yeasts which are doliporous (Filobasidium and a1 1 ies) from adoliporous yeasts such as Sporidi'obolus and Rhodosporidium. The larger information content ofZ5SrRNA permits superior systematic resolution (to the 1 eve1 of genus). Although it also inhibits sequencing, rRNA-DNA hybridization yields average base sequence homologies as precisely as required for determining relatedness. Were the dogma valid, the phylogeny of basidiomycetous yeasts should be the same by either method. 255 rRNA homoloav within the aenera Filobasidiell a, Fi 1obasidium;- ~eucos~oridi;m, andTEdosporidium and within the form-genera Cryptococw Rhodotorul a. and Vanriia is conaruent with suaaested morphological definition of the;e genera, butdieither with the weight given to dolipores in this group nor with assimilation characters. Since these yeasts are more homologous with each other than with Sporidiobolus or Ustilago, the 5s rRNA phylogeny is in blatant EFEFadiction to 255 rRNA phylogeny. Ribosomal RNA homology is not an evolutionary yardstick, but a complex and conservative character useful in conjunction with other, preferably morphological, characters.
M.P. WACH, A. SRISKANTHA, K. KOONS, B. SCHLAGNHAUFER, and C.P. ROMAINE, Department of Plant Pathology, The Pennsylvania State University, University Park, PA 16802. An analysis of the viruses associated with LaFrance disease of Agaricus bisporus. The name LaFrance disease is used to describe a serious malady of the cultivated mushroom, Agaricus bisporus (Lange) Imbach which is associated with several types of virus-like particles (VLPs). Sporophore isolates were analyzed for double-stranded RNA (dsRNA) by gel electrophoresis and for VLPs and a bacilliform virus by two seroassays and/or electron microscopy to further clarify the etiology of the disease. DsRNA was detected in 19 of 65 isolates and was correlated with reduced yields and, in some cases, deformed sporophores. From 2 to 12 dsRNA species xith molecular weights ranging from 4.3 to 0.21 x 10 were associated with the disease. Solid support hybridization experiments suggested that most dsRNAs represent unique nucleotide sequences. Diseased sporophore isolates also contained predominantly 19 nm and 25 nm spherical particles. The dsRNAs most frequently isolated from intact sporophores copurified with these two particles Additionally, an RNA-dependent RNA polymerase activity was detected in spherical particle-enriched preparations. Also, a single-stranded RNA bacilliform virus was encountered in ca. 70% of diseased sporophore isolates. A 280 bp copy DNA of the genomic RNA was cloned to establish a spot test for the detection of the bacilliform virus and in an effort to construct a gene vector for A. bisporus. 'present address : Monterey Mushrooms, Research Laboratory, P.O. Box 189, Watsonville, CA.95077. C.A. WAGNER.. Department of Botany, Ohio University, Athens, Ohio 4570i. Fine structure of the zoospores of Woronina pythii (~lasmodiophoromycetes). Free-swimming primary and secondary zoospores of ~oronina - thii , an endoparasite of Pythium (Oomycetpbere examined with electron microsco~v. The two tv~es of zoospores are ~ltrasiructurall~ inhistinqishable. Nuclei are electron-opaque with electron-translucent re~ions. Kinetosomes are 5OOnm long and occur in pairs that describe an angle ranping from 70-105 devees with respect to each other. Kinetosome cores contain clusters of dense-staining material. The kinetosomes are demarcated by a terminal plate at the distal end, proximal to the transition zone. A second plate, comparable to the axosomal plate described in many protozoans, defines the proximal end of the flagellum. Each kinetosome is associated with two simple microtubular rootlets. One consists of a pair of microtubules which appear to end at the plasmalemma a short distance from where the flagellum emerges. The second consists of three parallel microtubules which curve and follow the plasmalemma two-thirds of the way around the zoospore. The fine structure of g. pythii ZOOspores is compared with existing accounts of zoospore ultrastructure in other taxa of the Plasmodiophoromycetes. 43 W.F. WALKER. Department of Biochemistry, Dalhousie University, Halifax, Nova Scotia, S3H 4H7. 5s ribosomal RNA sequences and ascomycete phylogenetics. A phylogenetic tree for ascomycete 5s rRHA sequences is constructed. The endomycetales yeast sequences form a diverse main branch. All sequences from mycelial ascomycetes form another main branch of about equal diversity. Sequences from Pl ectomycetes, Pyrenomycetes and Discomycetes appear to be about equidistant from each other. Sequences from Schizosaccharomyces pombi and Protomyces inundatus clearly form the most isolated sequence lineages. The P. inundatus sequence is nearly equidistant from ascomycete and ba~idiom~cete sequences. Prel imi nary results from 5.8s sequence data more clearly indicate a closer clustering of the P. inundatus sequence with basidiomycete sequences. Thus, present RNA sequence data are consistent with an origin of the basidiomycetes from an ascomycete somewhat resembl i ng Protomycetales or presumably Taphri nales. Wampler, J. E., see Lingle, W. L., et. al. Ware, C. T., see Hammill, T. M., et. al., a. Washino, R. K., see Kerwin, J. L., et. al. D. J. WEBER, E. D. BUNDERSON, and C. V. BUNDERSON Department of Botany and Range Science, Brigham Young University, Provo, UT 84602. Interactive videodisc as a tool in teaching mycological laboratories. Preparing quality teaching laboratories in mycology can present unique challenges. Actively growing and/or sporulatinq fungi are rarely accessible in the field. Living laboratory specimer.~ are difficult to maintain, and preserved collections are of limited value. An intelligent interactive videodisc, with still and motion pictures, audio commentary and interactive capacity for student control has been prepared to teach the identification and classification of fleshy fungi. Over 1500 species have been included on the disc with illustrations, graphics and descriptive material. Principles of morphology, taxonomy, physiology and ecology are presented in an instructionally designed format. The videodisc can be used as a complete laboratory experience for students, as review and practice to complement laboratories, as supplementary lnaterial for teaching mycological principles, or as a "field guide" for anyone interested in identifying fleshy fungi. The videodisc requires a videodisc player, a TV mo~itor and a n~icrocomputer. Software should be available for several microcmputers including the IBM-PC and the Apple Placintosh. Weber, N. S., see Cibula, W . G., et. al. A. L. WELDEN. Department of Biology and Mesoamerican Ecology Institute, Tulane University, New Orleans, LA 70118. Some distributional Patterns of the Higher Fungi of the Gulf Coast. The higher fungi of the Gulf Coast of the United States compose an unusual population of tropical, subtropical, and temperate zone species. Probably
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1985 - Mycological Society of America

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