Program Book - 27th Fungal Genetics Conference

CONCURRENT SESSION ABSTRACTSSaturday, March 16 2:00 PM–5:00 PMKilnEnvironmental MetagenomicsCo-chairs: Chris Schadt and Betsy ArnoldMicrobial Responses to a Changing Climate: Implications for the Future Functioning of Terrestrial Ecosystems. Donald R. Zak. University of Michigan, AnnArbor, MI.Soil harbors a phylogenetically diverse community of microorganisms whose physiological activity mediates the biogeochemical cycling of carbon andnitrogen at local, regional, and global scales. These microbial communities are structured by the physical environment as well as the availability of growthlimitingresources (i.e., organic compounds in plant detritus). Presently, human activity is manipulating both the physical conditions and the availability oflimiting resources to soil microbial communities at a global scale, but the implications of doing so for the future functioning of ecosystems is presentlyunclear. In this presentation, I will discuss the ways in which humans are manipulating the ecological constraints on microbial communities in soil, thecompositional and functional responses that may result, and identify gaps in our knowledge that limit our ability to anticipate the response of microbialcommunities and ecosystem processes in a changing environment. Using an array of metagenomic approaches, I will provide evidence that rates ofatmospheric N deposition expected in the near future can down regulate the transcription of fungal genes with lignocellulolytic function, thereby alteringmicrobial community composition, slowing plant litter decay, and increasing soil C storage. This mechanism is not portrayed by any biogeochemical modelsimulating ecosystem response to atmospheric N deposition, and it demonstrates that microbial communites in soil may respond to a changingenvironment in ways that have unanticipated consequences for the future functioning of terrestrial ecosystems.The Interaction of Mycoplasma-related Endobacteria with their Arbuscular Mycorrhizal Fungal Host. Mizue Naito 1 , Teresa Pawlowska 2 . 1) Dept. ofMicrobiology, Cornell University, Ithaca, NY; 2) Dept. of Plant Pathology & Plant-Microbe Biology, Cornell University, Ithaca, NY.Arbuscular mycorrhizal fungi (AMF), comprising the monophyletic phylum Glomeromycota, are obligate biotrophs, and form symbiotic associations with80% of terrestrial plants. AMF associate symbiotically with the roots of plants, and are specialized in the transfer of nutrients from the soil to the planthost. In return for increased nutrient uptake, the plants supply AMF with up to 20% of their photosynthetically derived carbohydrates. Thus, AMFsymbiosis contributes significantly to global nutrient cycling and terrestrial ecosystems. AMF have been known to harbour two types of bacteria in theircytoplasm: (i) the Burkholderia-related Candidatus Glomeribacter gigasporarum and (ii) a Mycoplasma-related bacteria, which we refer to as Mycoplasmarelatedendobacteria (MRE). MRE live freely in the AMF cytoplasm, and have been found associated with all lineages of AMF worldwide. Virtually nothingis known about the MRE, such as their evolution, biological capabilities, and whether they are mutualists or parasites of their AMF hosts. In order tounderstand the nature of this symbiosis, and determine the role that the MRE play in arbuscular mycorrhizae, next generation sequencing (Roche 454 andIllumina) was performed on MRE isolated from 3 distinct AMF hosts, Claroideoglomus etunicatum, Funneliformis mosseae, and Racocetra verrucosa.Phylogenetic reconstruction and divergence dating using 22 conserved genes have revealed that MRE form a novel monophyletic subclade of theMycoplasmas and have diverged from their Mycoplasma relatives at least 400 million years ago, which may indicate the establishment of the MRE-AMFassociation to be quite ancient. Analysis of annotated genes have revealed novel proteins that are likely to play a role in interacting directly with the fungalhost. Preliminary data suggest that MRE are important in enabling the completion of the life cycle of their AMF hosts.Metagenomic analysis reveals hidden fungal diversity in grass rhizosphere and tree foliage. Ning Zhang 1 , Stephen Miller 1 , Shuang Zhao 1 , Hayato Masuya 2 .1) Plant Biology and Pathology, Rutgers Univ, New Brunswick, NJ; 2) Dept Forest Microbiology, Forestry and Forest Products Research Institute,Matsunosato 1, Tsukuba, Ibaraki 305-8687, JAPAN.The diversity of microorganisms on earth remains poorly understood. Unculturable fungi inhabiting rhizosphere, phyllosphere, and other less studiedniches are thought to represent a large fraction of the unknown diversity. In this study, we used both culture-dependent method and Illuminametagenomic sequencing approach to explore fungal diversity in two environments: grass (Poa pratensis, Kentucky bluegrass) rhizosphere and tree(Cornus spp., dogwood) foliage. For the grass rhizosphere sample, Illumina metagenomic analysis identified 1,192 fungal genera from 20.8 million reads,while the culture-based method identified 21 genera. For the Cornus sample, metagenomic analysis identified 73 fungal genera from 6.6 million reads,while 22 genera were isolated from culture. From both cases, we found that metagenomic sequencing analysis revealed significantly higher fungaldiversity than culture-based method, which will help us better understand the diversity and role of fungi in the ecosystem.Host-to-pathogen gene transfer facilitated infection of insects by a pathogenic fungus. Weiguo Fang, Xiaoxuan Chen. College of Life Sciences, ZhejiangUniversity, Hangzhou, Zhejiang, China.Inspite being of great concern to human health and the management of plants and animals, the mechanisms facilitating host switching of eukaryoticpathogens remain largely unknown. The endophytic insect-pathogenic fungus Metarhizium robertsii evolved directly from endophytes and itsentomopathogenicity is an evolutionarily acquired characteristic. We found that M.robertsii acquired a sterol carrier (Mr-NPC2a) from an insect byhorizontal gene transfer (HGT). Mr-NPC2a increased the amount of ergosterol in hyphal bodies by capturing sterol from insect hemolymph, and thusmaintained cell membrane integrity and improved fungal survival rate. On the other hand, the reduction in sterol (substrate for molting hormonesynthesis) in insect hemolymph elongated larval stage, which allows the fungus to fully exploit host tissues and produce more conidia. This is first report ofHGT from host to a eukaryotic pathogen, and the host gene ultimately improved the infectivity of the pathogen.Structure and function of soil fungal communities across North American pine forests. Kabir Peay 1 , Jennifer Talbot 1 , Dylan Smith 1 , Rytas Vilgalys 2 , JohnTaylor 3 , Thomas Bruns 3 . 1) Dept. of Biology, Stanford University, Stanford, CA; 2) Dept. of Biology, Duke University, Durham, NC; 3) Plant & MicrobialBiology, UC Berkeley, Berkeley, CA.Fungi are a critical component of the diversity and function of terrestrial ecosystems. They regulate decomposition rates, facilitate plant nutrient uptakeand have a profound impact on agriculture and economics. Understanding the forces that structure fungal communities thus has important theoretical and27th Fungal Genetics Conference | 95