Program Book - 27th Fungal Genetics Conference

CONCURRENT SESSION ABSTRACTSWednesday, March 13 3:00 PM–6:00 PMKilnGenomics and MycorrhizaeCo-chairs: Anders Tunlid and Tom BrunsThe mycorrhizal genome initiative (MGI): Identification of symbiosis-regulated genes by using RNA-Seq. A. Kohler 1 , E. Tisserant 1 , E. Morin 1 , C. Veneault-Fourrey 1 , S. Abba 2 , F. Buscot 3 , J. Doré 4 , G. Gay 4 , M. Girlanda 2 , S. Herrmann 3 , T. Johansson 5 , U. Lahrmann 6 , E. Martino 2 , S. Perotto 2 , M. Tarrka 3 , A. Tunlid 5 , A.Zuccaro 6 , I. Grigoriev 7 , F. Martin 1 . 1) Lab of Excellence ARBRE, Tree-Microbes Department, INRA-Nancy, Champenoux, France; 2) Dipartimento di Scienzedella Vita e Biologia dei Sistemi, Università di Torino,Torino, Italy; 3) Department Soil Ecology, UFZ Centre for Environmental Research Leipzig-Halle Ltd.,Halle, Germany; 4) Ecologie Microbienne UMR CNRS 5557, USC INRA 1193, Universite Claude-Bernard LYON 1, Villeurbanne, France; 5) Microbial Ecology,Lunds University, Lund, Sweden; 6) Max-Planck Insitute for Terrestrial Microbiology, Marburg, Germany; 7) DOE Joint Genome Institute, Walnut Creek,California, USA.Genome and transcriptome analyses of Laccaria bicolor and Tuber melanosporum (Martin et al., 2008, 2010) revealed that the ectomycorrhizal symbiosisprobably developed several times during evolution by generating different ‘symbiosis molecular toolkits’. In L. bicolor a large set of small-secreted proteinsacts as putative effectors but not in T. melanosporum, while the up-regulation of transporter-coding genes seems to be a common feature of bothinteractions. To better understand the evolutionary origin of mycorrhizal symbiosis and to elucidate the molecular mechanisms involved, a largesequencing project of species from different taxa, phylogenetic clades and symbiotic lifestyles (ectomycorrhizae, ericoid and orchid mycorrhizae) wasstarted in 2011 by the Joint Genome Institute and the mycorrhizal genome initiative. To identify and to compare symbiosis-regulated genes large scaleIllumina transcriptome sequencing of mycelium and mycorrhizal roots from Paxillus involutus, Piloderma croceum, Hebeloma cylindrosporum, Sebacinavermifera, Tulasnella calospora and Oidiodendron maius was performed. Small-secreted proteins, transporters, CAZymes but also many lineage specificproteins were among the highly up-regulated transcripts.Martin, F., Aerts, A., Ahrén, D., Brun, A., Duchaussoy, F., Kohler, A., et al. 2008. The genome sequence of the basidiomycete fungus Laccaria bicolorprovides insights inot the mycorrhizal symbiosis. Nature 452 :88-92Martin, F., Kohler, A., Murat, C., Balestrini, R., Coutinho, P.M., Jaillon, O., Montanini, B., et al. 2010. Périgord black truffle genome uncovers evolutionaryorigins and mechanisms of symbiosis. Nature 464 :1033-1038.Transposable element dynamics in the Amanita: insights on the evolution of genome architecture accompanying the transition from saprotrophic toectomycorrhizal ecologies. Jaqueline Hess 1 , Inger Skrede 2 , Anne Pringle 1 . 1) Organismic and Evolutionary Biology, Harvard University, Cambridge, MA; 2)Microbial Evolution Research Group, Department of Biology, University of Oslo, Oslo, Norway.Transposable elements (TEs) form an integral structural part of the genomes of many higher Eukaryotes. Their ability to proliferate independently andinto a large number of copies can lead to extensive amounts of repetitive DNA that is of no obvious benefit to the host. At first thought to be relativelyunderrepresented in Fungi, genome sequencing over the last decade has led to the discovery of many fungal genomes that are densely populated withTEs. Among those are the genomes of the ectomycorrhizal (ECM) fungi Laccaria bicolor (around 30% TE) and Tuber melanosporum (around 60% TE) as wellas a number of fungal pathogens, including Puccinia graminis and Melamspora larici-populina (both around 45% TE). The high TE content in these species,especially when compared to saprotrophic fungal species, suggests an association between symbiotic ecology, both mutualistic and antagonistic, and theability of TEs to invade and persist in their genomes. However, the mechanisms for this are currently not well understood. In order to assess whether highTE content is a feature of other ECM species and to get a more detailed picture of TE content changes around the transition from free-living to ECMecology, we have sequenced the genomes of five members of the genus Amanita: three ECM species and two saprotrophs, as well as the saprotrophicoutgroup Volvariella volvacea. Using the draft genome assemblies, we have developed methodology to estimate TE content from short-read data andexamine changes therein within quantitative and phylogenetic frameworks. Overall, we find no direct relationship between ECM status and increased TEcontent in the Amanita but instead discover patterns that suggest population genetics to be a strong driver of TE content. We will discuss our findings withrespect to the influence of TEs in the evolution of genome architecture around the origin of ECM symbiosis.Broad compatibility in the root endophyte Piriformospora indica is associated with host-adapted colonization strategies. Urs Lahrmann, Yi Ding, AlgaZuccaro. Organismic Interactions, MPI Marburg, Marburg, Germany.Their host range defines plant associated fungi as either specialists, which are adapted to one or few distinct hosts, or generalists who are able to thrivein highly variable host environments. Specialists and their hosts are in an evolutionary arms race that leads to the development of weapons perfectlytailored to the respective host. Conversely, broad-host range species must evolve adaptations to cope with a plethora of different host-associated signalsand host-specific defense mechanisms. The evolutionary force, in this case, drives the expansion and diversification of the fungal arsenal and the hostadaptedgene expression to better suite different plants. The mechanisms underpinning broad compatibility in root symbiosis are largely unexplored. Thegeneralist root endophyte Piriformospora indica that stimulates growth, alleviates salt stress and induces systemic resistance to pathogens in differenthosts can establish a long lasting interaction with the roots of barley and Arabidopsis, two morphologically and biochemically very distinct plants. We showhere that in these two hosts, root colonization proceeds very differently. While in Arabidopsis the fungus establishes and maintains biotrophic nutritionwithin living epidermal cells, in barley the symbiont undergoes a nutritional switch to saprotrophy that is associated with the production of secondarythinner hyphae (SH) in dead cortex cells. Consistent with a diversified trophic behavior, genome-wide expression profiling revealed a strong induction ofgenes encoding cell wall degrading enzymes and nutrient transporters in barley but not in Arabidopsis at a late colonization stage. In particular smallsecreted proteins (SSPs < 300 amino acids) known as effectors have been shown to facilitate colonization by manipulating host defense andreprogramming plant metabolism during symbiosis. Expression of P. indica genes encoding SSPs was induced in both hosts at different symbiotic stage, butthe majority of these SSPs were either Arabidopsis or barley responsive with the larger number expressed during biotrophy in Arabidopsis and duringsaprotrophy in barley. Our study reveals that broad compatibility in root endophytes requires strong phenotypic plasticity and the expression ofalternative lifestyle strategies in a host-dependent way.27th Fungal Genetics Conference | 39