Program Book - 27th Fungal Genetics Conference

CONCURRENT SESSION ABSTRACTSThursday, March 14 3:00 PM–6:00 PMScrippsGenomics and Biochemistry of Degradation of Complex Molecules in the EnvironmentCo-chairs: Jonathan Walton and Dan CullenFungal transcriptome as database for proteome and refinement tool of gene annotation. K. Igarashi 1 , C. Hori 1 , M. Ishiguro 1 , Y. Uemura 2 , A. K. Takeda 2 , S.Kaneko 3 , M. Samejima 1 . 1) University of Tokyo, Tokyo, Japan; 2) Genaris, Inc., Kanagawa, Japan; 3) National Food Research Institute, Ibaraki, Japan.So far, wood-rotting basidiomycetes, such as white-rot and brown-rot fungi, are the organisms known to grown on wood. They produce various enzymesto outside of their cell, extracellular part of the mycelia, in order to degrade major components of plant cell wall such as cellulose, hemicellulose andlignin. There are many enzymes, which can be utilized for the biomass conversion, in those fungi, as well as the proteins helping and/or accelerating thedegradation of the plant cell wall. Therefore, combination of correct annotation of these genes and the proteome analysis of the extracellular enzymes arequite important for biomass utilization. In the present study, we have cultivated the white-rot basidiomycetes Flammulina velutipes (Enoki-take, wintermushroom) and Phanerochaete chrysosporium in various biomass-degrading culture, and the transcriptome databases were constructed by sequencing ofthe cDNA library using 454 sequencer. In F. velutipes, we identified 19 novel biomass-degrading enzymes including 12 carbohydrate-active enzymes(CAZymes) by 2-dimentional gel electrophoresis of extracellular proteins from cellulose-grown culture, using the transcriptome data as a referencesequence. In the case of P. chrysosporium, the transcriptome sequence data was also used to improve the gene annotation, and more than 1,000 genesare newly annotated by the algorithms refined by cDNA sequences. The improvement of gene annotation caused accurate prediction of introns andshowed unique monodispersed distribution of intron length in this fungus.Developmental regulation and cellulase gene expression in Trichoderma reesei. Irina S. Druzhinina 1,2 , Razieh Karimi-Aghcheh 1 , Lea Atanasova 1 , ChristianP. Kubicek 1,2 . 1) Microbiology Group, Institute of Chemical Engineering, Vienna, Austria; 2) Austrian Center of Industrial Biotechnology, c/o Institute ofChemical Engineering, Vienna University of Technology, Vienna, Austria.We have recently shown that expression of cellulase and hemicellulase encoding genes in Trichoderma reesei (teleomorph Hypocrea jecorina) isobligatorily dependent on the function of the protein methyltransferase LAE1. Its orthologue in Aspergillus nidulans, LaeA, is a part of the VELVET proteincomplex consisting of LaeA, VeA and VelB that regulates secondary metabolism and sexual reproduction. Here we have investigated a possible role ofVEL1, the T. reesei orthologue of A. nidulans VeA, in expression cellulase genes and the development of the fungus. The T. reesei vel1 gene is not expressedin the darkness and is expressed at a relatively low level under illumination. Deletion of the vel1 locus causes a complete loss of conidiation and essentialalteration in sexual development such as loss of formation of perithecia. Overexpression of vel1 under the constitutive expression signals of tef1 did notenhance conidiation in light or darkness. However it led to irregular formation of infertile perithecia in the darkness. Deletion of vel1 did not affectcellulase gene expression, but vel1 overexpression strongly enhanced it. Consistent findings were also obtained for expression of xylanase and b-xylosidasegenes. The stimulation of cellulase gene expression by overexpressing vel1 was dependent on a functional lae1 gene. Our data show that VEL1 controlsphotoinduced sexual development and light-independent conidiation. In addition, while vel1 overexpression stimulates cellulase gene expression, isdispensable for this process and its action is therefore different from that of LAE1.Parallel losses of genes associated with saprotrophy in ectomycorrhizal Agaricomycotina lineages. D. Floudas 1 , L. Nagy 1 , A. Kohler 2 , A. Kuo 3 , I. Grigoriev 3 ,F. Martin 2 , D. Hibbett 1 . 1) Biology, Clark Univ, Worcester, MA; 2) Lab of Excellence ARBRE, Tree-Microbes Department, INRA-Nancy, 54280 Champenoux,France; 3) DOE Joint Genome Institute, Walnut Creek, CA.Mushroom forming fungi (Agaricomycotina) play pivotal roles in the cycling of nutrients in terrestrial ecosystems. Agaricomycotina exhibit diverselifestyles including saprotrophs and symbionts, such as mutualistic ectomycorrhizas. Previously, as part of the Saprotrophic Agaricomycotina Project (SAP),we performed analyses of fungal genomes focusing on wood decayers, which suggested that white rot is the plesiomorphic nutritional strategy ofAgaricomycetes and emerged 300 million years ago at the end of Carboniferous era. Our analyses also suggested that the brown rot mechanism and themycorrhizal lifestyle of Laccaria bicolor have emerged from white rot ancestors. The transitions from white rot to brown rot have taken place several timesin Agaricomycotina and were accompanied by losses of genes encoding enzymes involved in lignin and crystalline cellulose degradation. A similar patternwas reconstructed for the transition from a saprotrophic towards a mycorrhizal lifestyle in L. bicolor, which was the first mycorrhizal species in theAgaricomycotina to have its genome sequenced. However, L. bicolor represents only one of many ectomycorrhizal lineages recognized acrossAgaricomycotina. Here, we present data from eleven newly sequenced mycorrhizal genomes of Agaricomycotina, generated under the auspices of theMycorrhizal Genomes Initiative (MGI), in addition to 8 new genomes of decayers from the SAP. With these new genomes in hand, we are able to explorehow the emergence of mycorrhizal lifestyles is associated with changes in numbers of genes encoding enzymes involved in degradation of plantbiopolymers. The results suggest that ectomycorrhizal lifestyles have emerged multiple times from both white rot and brown rot ancestors inAgaricomycotina. The transitions to the ectomycorrhizal lifestyle show parallelism in gene losses between L. bicolor and other mycorrhizalAgaricomycotina lineages. However, patterns of retention of genes encoding lignocellulolytic enzymes vary across ectomycorrhizal lineages. For example,cellobiohydrolases, which are involved in the degradation of crystalline cellulose, have been retained in several mycorrhizal lineages. The results suggestthat the emergence of ectomycorrhizal lineages in Agaricomycotina has been associated with different degrees of reduction of their saprotrophic ability.27th Fungal Genetics Conference | 61