Program Book - 27th Fungal Genetics Conference

FULL POSTER SESSION ABSTRACTSwhich can have enormous impacts on human and ecosystem health. Despite their ubiquity and importance, very little is known about the molecularmechanisms underlying these interactions. To address this, we select to study the interactions between Pseudomonas aeruginosa and Aspergillusfumigatus, the ubiquitous opportunistic bacterial and fungal pathogens, respectively, via redox-active bacteria-secreted phenazines. We hypothesize thatthe functions of these molecules are multifactorial, dependent on genetic and environmental factors. By combining genetic, physiological, electrochemical,and metabolic profiling strategies, here we report that redox-active phenazines can mediate biofilm interactions between P. aeruginosa and A. fumigatusin multiple ways, ranging from antagonistic to synergistic. We find that phenazine production patterns are generally correlated with bacterial-fungalinteraction phenotypes, in a genetically- and temporarily-dependent manner. Further, fungi can convert the precursor phenazine-1-carboxylate (PCA)produced by bacteria into several other phenazines. These structurally related phenazines come in with characteristic physical-chemical propertiesincluding redox properties. Our most striking finding is to be able to draw connections between a phenazine’s structure and its mode of action. Under onegiven condition, some phenazines such as phenazine-1-carboxamide (PCN) can facilitate bacterial biofilm development by inhibiting fungal development;some others such as pyocyanin (PYO) show no apparent effect on fungal development; and 5-methyl-phenazine-1-carboxylic acid (5-Me-PCA) cansynergistically facilitate both bacterial and fungal biofilm developments. In addition, we find that changing the ambient redox and pH conditions can affecta phenazine’s mode of action, likely via influencing its redox activity. Taken together, our findings imply that phenazines-mediated bacterial-fungalinteractions have profound and diverse effects on multicellular behavior in competitive and mixed-species biofilm environments.606. Genomic analysis of Mortierella elongata and its endosymbiotic bacterium. Gregory Bonito 1 , Andrii Gryganskyi 1 , Christopher Schadt 2 , Dale Pelletier 2 ,Amy Schaefer 3 , Gerald Tuskan 2 , Jessy Labbé 2 , Sofia Robb 4 , Rebecca Ortega 1 , Francis Martin 5 , Mitchel Doktycz 2 , Kurt LaButti 6 , Matt Nolan 6 , Robin Ohm 6 , IgorGrigoriev 6 , Rytas Vilgalys 1 . 1) Duke University, Durham NC; 2) Oak Ridge National Laboratory, Oak Ridge TN; 3) University of Washington, Seattle WA; 4)University of California, Riverside CA; 5) Institut National de la Recherche Agronomique, Nancy France; 6) Joint Genome Institute, Walnut Creek CA.Mortierella belong to a group of basal fungi (Mortierellomycotina) common to soils and the rhizosphere and endosphere of many plant species.Mortierella species are known for rapid growth and abundant lipid production. Mortierella elongata is one species commonly isolated from forest soils andhealthy plant roots where it grows asymptomatically as an endosymbiont. Mortierella elongata is a heterothallic species but can also reproduce asexuallythrough chlamydospores and sporangiospores. Recent reports indicate that some isolates of M. elongata host endosymbiotic bacteria, which may betransmitted vertically via spores. However, it is still unclear whether all Mortierella species host endosymbionts or whether these are lineage-specificassociations. Given the geographically widespread distribution of Mortierella elongata and its ubiquitous presence in forest soils and plants we chose tosequence its genome through the JGI Forest Metatranscriptome CSP. We also sought to assemble the genome of the bacterial endosymbiont to addresswhether there are genomic signatures of co-adaptation or co-evolution in the genomes of Mortierella and its endosymbiotic bacterium, which may impactthe function and growth of Mortierella elongata. The 50 Mb genome of M. elongata was sequenced to 112x coverage. Of the 220,113 putative proteinsidentified in M. elongata, 109,093 appear to be unique (e.g. only ~50% have orthologs in other fungal species having sequenced genomes). The M.elongata genome appears to be enriched in genes related to tryptophan metabolism, siderophore group nonribosomal peptides, glucan 1,4-alphaglucosidases, and in lipid metabolism (e.g. sphingolipids, etherlipids, and glycerophopholids) compared to genome sequences of other basal fungi. Theendosymbiotic bacterium sequenced along with the M. elongata isolate is related to Glomeribacter (endosymbiont of Gigospora, Scutellospora, and otherGlomeromycota) within the Burkholdariales. The ~2.6 MB endosymbiont genome is larger than that of Glomeribacter but quite reduced compared to freelivingisolates of Burkholdaria. The reduced genome size of this bacterium, and the fact that it has thus far evaded pure culture isolation, supports the viewthat this is an ancient and obligate symbiosis.607. Diversity and Content of Maize Leaf Endophytes are Correlated With Maize Genotype. Alice C. L. Churchill 1* , Santiago X. Mideros 1 , Peter Balint-Kurti 2 , Surya Saha 1 , Rebecca J. Nelson 1 . 1) Department of Plant Pathology & Plant-Microbe Biology, Cornell Univ, Ithaca, NY; 2) USDA-ARS Plant ScienceResearch Institute, Department of Plant Pathology, North Carolina State University, Raleigh, NC 27695.All plants contain endophytes that have the potential to provide fitness benefits to their hosts by increasing tolerance to environmental stressors,boosting plant nutrition and growth, and providing increased resistance or tolerance to insect pests and plant pathogens. We are characterizingendophytic populations inhabiting aboveground maize tissues with the goal of associating maize genetic variation with the diversity, structure andconstitution of maize-associated microbial communities. Nine maize lines, representing a diverse subset of the founders of the NAM (Nested AssociationMapping) population, were grown at a single North Carolina field site in 2012 and assayed for culturable endophytic bacteria and fungi. Two distinct seedsources for each maize line were planted in a randomized experimental design, and three replicates per seed source were assayed, representing a total of54 samples. Leaf pieces were harvested just prior to pollination for each maize line, surface sterilized using standard endophyte isolation methodologies,and ground leaf extracts were cultured on four media that select for slow- and fast-growing fungi and copiotrophic, diazotrophic, and oligotrophicbacteria. Approximately 65% of the samples contained one or more phenotypically distinct, culturable bacteria, 28% contained one or more fungi, 22%contained both bacteria and fungi, and endophytes were undetectable in 28% of the samples. A greater number and diversity of fungi were cultured fromtropical maize lines than from temperate lines. Bacteria were isolated from all maize lines, with some lines exhibiting significantly greater microbialcommunity diversity than others. Several phenotypically similar bacteria and fungi were isolated from multiple maize lines. Microbial identity via 16S andITS sequencing, as well as identification of unculturable endophytes via whole genome metagenomic sequencing, are in progress. We are particularlyinterested in identifying members of the microbiome that modulate disease symptoms caused by maize leaf and ear pathogens. Hence, future studies willfocus on in vitro and in planta endophyte-pathogen interactions.608. Characterisation of epichloae endophytes from the Triticeae and their potential use in modern cereals. Wayne R Simpson, Marty J Faville, Roger AMoraga, Richard D Johnson. Agresearch Grasslands, Palmerston North, New Zealand.Epichloae endophytes infect grasses within the subfamily Pooideae including some within the tribe Triticeae. There have been no accounts of moderndomesticated Triticeae hosting epichloae endophytes but there have been reports in Elymus, Hordeum and other grasses within the tribe. Our goal is toisolate epichloae endophytes from the wild relatives of modern cereals and inoculate these into modern cereal crops. We surveyed populations of Elymusand Hordeum, primarily from Asia, and selected 29 Elymus and 13 Hordeum infected plants. We used simple sequence repeats (SSR) and b-tubulinsequencing to determine genetic similarity, hybrid status and closest non-hybrid ancestor. SSR data indicates 26 genetically distinct strains that fall into 5major clades. b-tubulin analysis shows that the majority of our isolates had Epichloë bromicola ancestry, with both hybrid and non-hybrid strainsidentified. Within the non-hybrid E. bromicola two major clades were identified. Of the hybrids we identified examples of E. bromicola x E. typhina and E.bromicola x E. amarillans. Although E. bromicola has been observed in Asian grasses we believe that this is the first report of an E. bromicola x E amarillanshybrid. Of the remaining isolates, we found examples of strains with E. yangzii ancestry (all non-hybrids) and E. elymi ancestry (both non-hybrid and270