Program Book - 27th Fungal Genetics Conference

FULL POSTER SESSION ABSTRACTSdifferences across all chromosomes in the UK population of N. tetrasperma, while the other lineages show much fewer heteroallelic sites. Analysis of themating type chromosome reveals considerable variation in the sizes of putative regions of suppressed recombination in the 5 lineages of N. tetraspermainvestigated. We also present findings on the genome wide patterns of polymorphism within populations and divergence between populations, with theaim of dissecting which regions of the genome have been recently acted on by natural selection. The initial results gained in this study are showing thatmultiple N. tetrasperma populations have complex histories that have left strong signatures in their genomes.677. Rapid evolution of female-biased genes: a novel example from the eukaryotic model organism Neurospora crassa. Hanna Johannesson, CarrieWhittle. Evolutionary Biology, Uppsala University, Uppsala, Sweden.In animals and plants, sex-biased gene expression plays a major role in gene evolution. In particular, reproductive genes with male-biased expressiontend to exhibit rapid protein evolution and reduced codon bias as compared to female-biased or unbiased genes. Minimal data are available for fungi.Here, we demonstrate that sex-biased expression is associated with gene evolution in the filamentous fungus Neurospora crassa, but in contrast toanimals and plants, the rapid evolution occurs for female-biased genes. Based on analyses of >25,000 expressed sequence tags (ESTs) from male (conidial),female (protoperithecial) and vegetative (mycelial) tissues, we show that reproductive genes with female-biased expression exhibit faster proteinevolution and reduced optimal codon usage than male-biased genes and vegetative genes. Furthermore, our data suggest that female-biased genes arealso more apt to experience selective sweeps. The sex-biased expression effects are observable at the species and population level. We argue that therapid molecular evolution of female-biased genes is best explained by sexual selection via female-female competition, but could also result from matechoiceand/or directional natural selection.678. Fungal Community Dynamics During Biomass Degradation in the Cow Rumen Determined by ITS Sequencing. Hailan Piao 1,2 , Julien Tremblay 3 , RobinOhm 3 , Kanwar Singh 3 , Fernanda Haffner 4 , Stefan Bauer 4 , David Culley 2 , Kenneth Bruno 2 , Kerrie Barry 3 , Feng Chen 3 , Scott Baker 2,5 , Roderick Mackie 6 ,Susannah Tringe 3 , Igor Grigoriev 3 , Matthias Hess 1,2,3,5* . 1) Washington State University, Richland, WA; 2) DOE Pacific Northwest National Laboratory,Richland, WA; 3) DOE Joint Genome Institute, Walnut Creek, CA; 4) Energy Biosciences Institute, UC Berkeley, Berkeley, CA; 5) Environmental MolecularScience Laboratory, Richland, WA; 6) University of Illinois, Urbana-Champaign, IL.The microbial community that inhabits the cow rumen is composed of Archaea, Bacteria and Eukarya and is well known for its biomass-degrading ability.In order to understand this ecosystem at the whole-systems level it is important to monitor the dynamics of the individual community members.Sequencing of the 16S rRNA gene has been used intensively to obtain insights into the ecology of the prokaryotic fraction of the microbial rumencommunity. To obtain insights into the ecology of the fungal fraction of the rumen community and its dynamics during biomass-degradation, we amplifiedthe ITS2 region from fungi that colonized corn stover and switchgrass during rumen incubation. Amplicons were generated from rumen-incubatedswitchgrass and corn stover and rumen fluid at six different time points and from two different host animals. Sequencing on Illumina’s MiSeq platformresulted in a total of 10,675,384 sequences with an average read length of ~240bp amounting to a total of >2.6 Gbp of sequence information. Succeedingsequence analysis revealed a fungal community of low complexity, with two phyla as the dominant players. Members of the phylumNeocallimastigomycota were absent on the pre-incubated biomass and appeared to colonize both corn stover and switchgrass throughout the incubationprocess. Members of the phylum Ascomycota were less dominant (