Program Book - 27th Fungal Genetics Conference

FULL POSTER SESSION ABSTRACTSDurham, NC; 2) Department of Plant Pathology, North Carolina State University, Raleigh NC; 3) School of Plant Sciences, University of Arizona, Tucson AZ;4) Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, MN.Many foliar fungal endophytes are transferred horizontally among plant hosts and exhibit various degrees of host specificity. For example, endophyticLophodermium species (Rhytismatales) are commonly found in needles of certain pine species but infrequently in broad leaves of angiosperm hosts. Suchendophytes may have populations or subspecies that are genetically structured according to their host preference, climate regimes or geographic ranges,which might be associated with increased fitness for plants hosting specific mutualistic endophytic fungi. Hence, we set out to explore the populationstructure of Lophodermium spp. within mature foliage of loblolly (Pinus taeda) and Virginia pine (Pinus virginiana) in southeastern U.S., covering hostranges from the mountains of Appalachia to the coasts of the Atlantic. We analyzed the nuclear ribosomal internal transcribed spacer (ITS1/5.8S/ITS2) andthe intragenic spacer (IGS) regions as well as three protein-coding genes (actin, calmodulin, chitin synthase I) of the isolated Lophodermium strains. Thesein-depth population genetic analyses of endophyte species provide insight into the capacity of multilocus genetic markers that resolve on differentevolutionary time scales to capture sub-species level structure and to identify criteria for species delimitation. This multilocus analysis identified a rarecryptic species, which possibly explains the high genetic diversity of the Lophodermium spp. Genetic and geographic distance were correlated in the rarecryptic species, but not in the common species. We found no evidence for host species preference for the cryptic species vs. the common species. Ourfindings suggest that genetic exchange and recombination can be limited by dispersal if the species is rare.686. Fungal pathogen and endophyte genetics within the context of forest community dynamics. M.-S. Benitez 1 , M. H. Hersh 2 , L. Becker 1 , R. Vilgalys 3 , J. S.Clark 1,3 . 1) Nicholas School of the Environment, Duke University, Durham, NC; 2) Department of Biology, Eastern Michigan University, Ypsilanti, MI; 3)Department of Biology, Duke University, Durham, NC.Fungal pathogens play important roles in forest community dynamics, particularly through negative-density dependent regulation. Negative-densitydependence regulation is hypothesized to be regulated by the presence of host-specific pathogens. Studies on forest pathogens, however, indicate thepredominance of generalist seedling pathogens, capable of infecting more than one host species. To understand the mechanisms through which“generalist” pathogens contribute to forest-community dynamics we conducted extensive surveys of seedling pathogens in temperate hardwood forestsof the eastern U.S.A. Species in the genera Colletotrichum and Ilyonectria were among the most commonly isolated and recovered amplicon sequencefrom seedlings of multiple host species showing disease symptoms. Further, co-infection by both Colletotrichum and Ilyonectria species decreases hostsurvival, as quantified by posterior model probabilities. To investigate molecular mechanisms associated with multi-host generalism and co-infection, andto determine whether these “generalist” pathogens are distinct species or species-complexes, the genomes of three common species in our dataset (e.g.C. fioriniae, C. gloesporoides and Ilyonectria europea) were sequenced. The largest genome of the three belonged to Ilyonectria at 63.66 Mb, which alsocontained the highest number (22,250) of genes. The smallest genome belonged to C. fioriniae with 50.04 Mb and 15,777 genes. Genome size and numberof predicted genes appears expanded, confirming their role as seedling pathogens. For instance, three out of four polysaccharide lyase (PL) enzymedomains found in fungal genomes, are enriched in these three species. PL enzymes are relevant in plant pathogenicity since they may contribute to initialstages of host penetration. The genome sequence of these fungal groups will serve as a reference set for population level studies to address hostspecificityand local adaptation within our isolate database.687. Discovery of Sexual Reproduction in the Black Aspergilli. Heather L. Darbyshir 1 , Peter JI. van de Vondervoort 2 , Paul S. Dyer 1 . 1) School of Biology,University of Nottingham, Nottingham, NG7 2RD United Kingdom; 2) DSM Biotechnology Center, PO Box 1, 2600 MA Delft, The Netherlands.The black aspergilli are members of the genus Aspergillus that are typically characterized by the production of dark or black asexual conidia (classified assection Nigri). The group includes Aspergillus niger, which is of particular industrial importance because of its safe use status and ability to produce a widerange of enzymes and organic acids. All members of the black aspergilli have previously only been known to reproduce by asexual means. However, as aresult of combined molecular and cultural experimental studies it can now be revealed that at least one member of the black aspergilli, Aspergillussclerotiicarbonarius, is able to complete a sexual cycle. Wild type isolates of A. sclerotiicarbonarius were found to retain the ability to form sclerotia,structures associated with both dormancy and sexual reproduction, and strains of complementary MAT1-1 and MAT1-2 could be identified based on thepresence of mating-type genes. Crossing strains of opposite mating type, and an extended period of incubation, resulted in the production of sclerotiacontaining multiple ascocarps, with asci and viable ascospores, within the matrix of a sclerotium. This is consistent with past studies of phylogeneticallyrelated species in the Aspergillus section Flavi (teleomorph genus Petromyces). Progeny analysis is being undertaken based on data arising fromcomparative genome sequencing of parental isolates, mating-type distribution and phylogenetic analysis. The discovery of a heterothallic sexual cycle in A.sclerotiicarbonarius provides insights into the evolution of asexuality in the black aspergilli. It is hoped that ongoing molecular genetic studies into theearly sexual morphogenesis may provide an insight into the regulation of sexual reproduction in the black aspergilli.688. Culture-based survey of soil fungi from bat hibernacula. Jeffrey M. Lorch 1 , Daniel L. Lindner 2 , Andrea Gargas 3 , Laura K. Muller 4 , Andrew M. Minnis 2 ,David S. Blehert 4 . 1) University of Wisconsin - Madison, Madison, WI, USA; 2) US Forest Service, Northern Research Station, Center for Forest MycologyResearch, One Gifford Pinchot Drive, Madison, WI, USA; 3) Symbiology LLC, Middleton, WI, 53562, USA; 4) US Geological Survey - National Wildlife HealthCenter, Madison, WI, USA.Bat white-nose syndrome (WNS), a fungal disease now spreading in eastern North America, is causing unprecedented mortality among hibernating bats.To investigate fungal communities present in bat hibernacula, we identified culturable fungi present in soil samples from 24 bat hibernation sites in theeastern United States. Isolates were characterized by sequencing regions of ribosomal DNA (internal transcribed spacer and partial intergenic spacer). Weisolated Geomyces destructans from soil samples collected in hibernacula within the known range of WNS, and we found a wide diversity of Geomycesspecies, comprising around one third of all isolates. Many of these Geomyces species, along with numerous potentially novel lineages, appear to beundescribed.Other Topics689. Understanding the cellular basis of Azole resistance in Aspergillus fumigatus. Michael J. Bromley, Marcin Fraczek, Rebecca Collins, Emma Davies,Paul Bowyer. Translational Med, Univ Manchester, Manchester, United Kingdom.Resistance of Aspergillus fumigatus to the azole class of antifungals is becoming a major problem in Europe and is being driven by two factors, theprolonged exposure (several months to several years) of patients to azoles and the extensive use of agricultural azoles driving environmental resistance.Our understanding of the mechanisms that govern azole resistance in filamentous fungi is limited. While some clinical resistant isolates harbor mutations290