Program Book - 27th Fungal Genetics Conference

FULL POSTER SESSION ABSTRACTSmating efficiency and outcrossing ability after four weeks, therefore it was chosen as an additional ‘supermater’ pair for community use in mating projects.It is important to have alternative tester strains to allow for unexpected mating differences when crossing isolates of diverse genetic origins. This isbecause factors such as heterokaryon incompatibility (het) loci and single nucleotide polymorphisms, can considerably influence sexual compatibility. Theworldwide fertility screen found that approximately 85% of isolates are sexually fertile, indicating that sexual reproduction should be possible in naturewhen suitable environments are present. Next, the plasticity of sexual crossing conditions was tested, to determine whether they could be manipulated toincrease fertility in crosses involving low-fertility strains of interest. A range of environmental and growth conditions were examined, including incubationtemperature, CO 2 level, and oatmeal agar type. Fertility levels were significantly affected by certain parameters. Work is ongoing to integrate these factorsto further optimize fertility in the ‘supermater’ pairs.641. Understanding the dynamic plant pathogen Ramularia collo-cygni at both the sequence and field level. James Fountaine, Peter Hoebe, MaciejKaczmarek, Marta Piotrowska, Neil Havis. Crop and Soils Systems Research, Scotland's Rural College, Edinburgh, Scotland, United Kingdom.The fungus Ramularia collo-cygni is the major biotic agent involved in Ramularia Leaf Spot (RLS). The fungus produces necrotic lesions on leaves,primarily after flowering takes place in the host plant. Despite being initially reported on crops in Italy in the late 19th Century RLS only became aneconomic pathogen of barley in the late 20th Century. The geographical spread of the disease now covers much of Europe, North and South America andNew Zealand. Research in the last decade, using molecular tools, has helped elucidate the life cycle of the fungus and has indicated a seed borne stage.These tools have also allowed detailed testing of spring barley archive samples, which has revealed a significant increase in pathogen levels since the1990’s. The pathogen appears to develop rapid resistance in the field to fungicides and mutations conferring resistance have also been detected in thearchive samples. Ramularia collo-cygni is currently classified as a member of the Mycosphaerella genera and sequence data derived within our groupsuggests a genetic similarity between R. collo-cygni, Mycosphaerella graminicola and M. fijiensis. These sequences focus primarily on the genes associatedwith the target sites for fungicides, such as Beta tubulin, Cytochrome b, Succinate dehydrogenase and eburicol 14a-demethylase (CYP51) genes. Thispresentation will demonstrate our current knowledge of this fungal pathogen and highlight the newly obtained genome and transcriptomic datagenerated by the combined approach of illumiina/solexa and Roche/454 sequencing. This combined approach has enabled the assembly of a completegenome sequence. The finished assembled genome of R. collo-cygni is 30.2 Mb and is currently to be found in 355 contigs. The complete annotation of thisgenome is currently underway using the FGENESH 2.6 software to generate first consensus gene calls. This approach will allow for comparative genomeanalysis in related genomes which will help to address the biology of R. collo-cygni in areas such as pathogenicity, population genetics and fungicideresistance. These advances should enable a greater understanding of the complex relationship between the fungus and host plant and furthermore, assistin the development of environmentally sound strategies to control this increasingly important disease of barley production systems.642. Comparing germination dynamics of conidia and ascospores from natural isolates of Neurospora crassa. Kolea C.K. Zimmerman 1 , Dan Levitis 2 , AnnePringle 1 . 1) Organismic and Evolutionary Biology, Harvard University, Cambridge, MA; 2) Max Planck Institute for Demographic Research, Rostock,Germany.Many organisms experience high mortality during the first stages of growth. This is especially relevant in fungi because of the large ratio betweenpropagules produced and the number of those propagules that germinate and grow into a mature mycelium. Furthermore, in many organisms, asexuallyreproduced progeny have higher survival rates compared to sexually reproduced progeny. We have developed a high throughput pipeline using flowcytometry to analyze spore germination dynamics and have applied this pipeline to study the germination differences between asexual and sexual spores.Specifically, we applied this pipeline to study variation in germination of Neurospora crassa conidia and ascospores from 32 natural isolates and crossesamong these isolates, respectively. Using publicly available sequence data, we computed all pairwise genetic distances between the 32 strains and crossedstrains of varying genetic distance from each other to determine the effects of parent relatedness on ascospore viability. We found that viability of asexualspores is higher than viability of sexual spores in most cases and there is no clear linear relationship between genetic relatedness and ascospore viability.Future work will include experiments to evaluate the ability of sexual recombination to purge deleterious mutations. The data from these experiments willhelp us quantify the relative costs and benefits of asexual vs. sexual reproduction in Neurospora crassa and inform evolutionary theories on the evolutionof sex.643. Cryptococcus gattii and the origins of outbreaks. Tien Bui 1 , Anna Foley 1 , Leona Campbell 1 , Patrick Brunner 2 , Bruce McDonald 2 , Dee Carter 1 . 1) Schoolof Molecular Bioscience, University of Sydney, NSW 2006, Australia; 2) Institute of Integrative Biology, ETH, 8092 Zurich, Switzerland.Cryptococcus gattii and its sibling species C. neoformans cause cryptococosis in humans and a range of animal. Strains within these species fall into anumber of distinct molecular genotypes, and these vary in their ecology, geographic distribution, and various virulence-associated phenotypes. In C. gattii,molecular type VGI is found worldwide, usually in warmer regions, and causes sporadic infection in apparently healthy people and animals. VGII is morerestricted in distribution, and while it also causes sporadic infection it is responsible for significant outbreaks that have expanded its geographic range intotemperate areas. VGIII infections occur predominantly in immunocompromised hosts in the southern California region, and cases of VGIV infection are sofar restricted to southern Africa, with a single case from India. Our interests lie in understanding the ecology and evolution of C. gattii in the environment,and how these relate to its ability to cause infection and outbreaks of disease. We have found the level of sexual recombination varies by molecular type,and that while in general the C. gattii population structure is sexual, this varies by genotype and in VGII is punctuated by periodic, clonal lineages. Here werefine our analysis using extended MLST data, haplotype networks and coalesence theory. We find the level of diversity among global VGI and VGIIgenotypes is highly constrained and comparable to some recently evolved plant pathogens, while the more geographically restricted VGIV genotype issubstantially more diverse. Outbreak VGII clones are highly derived with an apparent history of expansion and extinction events. Evidence for purifyingselection occurs at the master regulator of mating type for VGII, suggesting recombination is important in the generation of outbreak lineages.644. Evolution of the mating type locus in the species within and closely related to the pathogenic Cryptococcus species complex. Sheng Sun, JoshGranek, Joseph Heitman. Molecular Genetics & Microbiology, Duke University, Durham, NC.Cryptococcus amylolentus is the most closely related sister species to the pathogenic Cryptococcus species complex that includes the common humanpathogenic fungi Cryptococcus neoformans and Cryptococcus gattii. We recently reported that C. amylolentus has a tetrapolar mating system, in whichmating type is determined by two unlinked mating type (MAT) loci (A and B) that are located on different chromosomes. This is in stark contrast to themating systems in the species within the pathogenic Cryptococcus species complex, where all the species are bipolar and have a contiguous large (>100 kb)MAT locus. Thus, analyzing the tetrapolar MAT loci of C. amylolentus could provide insights into how the derived bipolar MAT locus in the pathogenicCryptococcus species complex evolved. In this study, we first provide a fully detailed characterization of both alleles for each of the two C. amylolentusMAT loci, illustrating expansion of the A MAT locus in C. amylolentus, as well as the chromosomal rearrangements between the alleles from the opposite27th Fungal Genetics Conference | 279