Program Book - 27th Fungal Genetics Conference

FULL POSTER SESSION ABSTRACTS601. Phylogenetic and genomic analysis of a novel, nematophagous species of Brachyphoris. S. Sharma Khatiwada, J. B. Ridenour, A. Thomas, J. Tipton, T.Kirkpatrick, B. H. Bluhm. University of Arkansas, Fayetteville, AR.Plant-parasitic nematodes are destructive pathogens of crops worldwide. The phase out of many chemical control methods has prompted a search forfeasible alternative control strategies. Nematophagous fungi are widely distributed in terrestrial and aquatic environments, and have evolved diversestrategies to parasitize nematodes. In this study, a previously characterized but unnamed nematophagous fungus (designated TN14) was taxonomicallyclassified and a draft genome sequence was obtained. Taxonomic identification of the fungus was conducted using the ITS1-5.8S-ITS2 rDNA sequences.Phylogenetic relationships were inferred with neighbor-joining and maximum likelihood methods. Based on the primary GenBank database search, the ITSregion of TN14 was compared with the ITS region of 41 taxa. From this analysis, the fungus is predicted to form a distinct monophylogenetic clade withBrachyphoris, a genus of nematophagous fungi related to Dactylella and Vermispora. Although some 200 species of nematophagous fungi are known,publicly available resources are very limited. Thus, we obtained a draft sequence of the TN14 genome via Roche-454 sequencing technology. Alignment ofover 90% of the sequenced reads revealed an estimated genome size of 100.1 MB, which is notably larger than the genomes of many other ascomycetes,including that of the only other sequenced nematophagous fungus, Arthrobotrys oligospora (40.07 Mb). Subsequent analyses of the genome of TN14 areproviding insight into molecular mechanisms underlying pathogenicity and the viability of TN14 as a potential bio-control agent in agricultural settings.602. The proteome of the traps of the nematode-trapping fungus Monacrosporium haptotylum . K-M. Andersson 1 , T. Meerupati 1 , F. Levander 2 , E.Friman 1 , D. Ahrén 1 , A. Tunlid 1 . 1) Microbial Ecology, Department of Biology, Lund University, Sweden; 2) Protein Technology, Department ofImmunotechnology, Lund University, Sweden.Nematode-trapping fungi have for a long time been seen as putative biological control agents against parasitic nematodes. A better knowledge on theinfection process will facilitate the development of these fungi as biological control agents and may also lead to the discovery of new nematicidal drugs.Monacrosporium haptotylum is a nematode-trapping fungus that captures nematodes using an adhesive trap called knob. In this study, proteins wereextracted from knobs and mycelium and analyzed using SDS-PAGE combined with LC/MS/MS. Peptides were matched against predicted gene models fromthe recently sequenced genome of M. haptotylum. Furthermore, the transcriptome in the knob during infection of nematodes were analyzed.The analysis showed that there was a large difference in the proteome of the knob compared to the mycelium. In total 336 proteins were identified. Aquantitative analysis showed that 54 proteins were expressed at significantly higher levels in the knobs versus the mycelium. Proteins containing apredicted secretion signals were overrepresented in knobs (knobs 41 %; mycelium 11 %). Five of the secreted proteins upregulated in knob were smallsecreted proteins (SSPs). Three of the SSPs were orphans since they showed no homology to the NCBI database and lack pfam domains. Interestingly, twoof them are upregulated in the transcriptome during infection of nematodes.Among the upregulated proteins were several putative cell-surface adhesins containing the carbohydrate binding domain WSC and repetitive regionsenriched in threonine/serine residues. Upregulated were also a diverse array of peptidases including serine endopeptidase (subtilisin), asparticendopeptidase, metalloendopeptidase, aminopeptidase and carboxypeptidase. Several proteins related to stress response and basic metabolism were alsoidentified in the trap proteome. During infection of nematodes, genes with the domains peptidase_S8 (subtilisin), DUF3129 and WSC are highlyupregulated in the knob.Taken together, our analysis shows that the trap cell has a unique proteome containing components that are involved in the early stages of infectionincluding adhesion and penetration of the nematode.603. Sequencing the in planta transcriptomes of Colletotrichum species provides new insights into hemibiotrophy. Richard J. O'Connell 1 , StéphaneHacquard 1 , Jochen Kleemann 1 , Emiel Ver Loren van Themaat 1 , Stefan Amyotte 2 , Michael Thon 3 , Li-Jun Ma 4 , Lisa Vaillancourt 2 . 1) Max Planck Institute forPlant Breeding Research, Cologne, Germany; 2) Department of Plant Pathology, University of Kentucky, Lexington, KY; 3) CIALE, Universidad de Salamanca,Villamayor, Spain; 4) Department of Biochemistry and Molecular Biology, UMASS Amherst, MA.Colletotrichum species cause devastating diseases on crop plants worldwide. Infection involves formation of a series of specialized cell-types associatedwith penetration (appressoria), growth inside living host cells (biotrophic hyphae) and tissue destruction (necrotrophic hyphae). To analyse thetranscriptional dynamics underlying these transitions, we used RNA sequencing to compare the transcriptomes of C. higginsianum infecting Arabidopsisand C. graminicola infecting maize. The early transcriptome is dominated by secondary metabolism and effector genes, suggesting both appressoria andbiotrophic hyphae are platforms for delivering protein and small molecule effectors to host cells. Genes encoding a vast array of wall-degrading enzymes,proteases and membrane transporters are up-regulated at the switch to necrotrophy, when the pathogen mobilizes nutrients from dead cells for growthand sporulation. However, the two species employ different strategies to deconstruct plant cell walls that are adapted to their host preferences. Thus, C.higginsianum activates more pectin-degrading enzymes during necrotrophy, whereas C. graminicola mostly activates hemicellulases and cellulases at thisstage. Remarkably, although appressoria formed in vitro are morphologically similar to those in planta, comparison of their transcriptomes showed >1,500genes are induced only upon host contact, suggesting that sensing of plant signals by appressoria dramatically reprograms fungal gene expression inpreparation for host invasion.604. Biological activities of natural products synthesized by the mammalian fungal pathogen, Histoplasma capsulatum. A. Henderson 1 , M. Donia 2 , M.Fischbach 2 , A. Sil 1 . 1) Microbiology and Immunology, UCSF, San Francisco, CA; 2) Department of Bioengineering and Therapeutic Sciences, University ofCalifornia, San Francisco, San Francisco, CA.Histoplasma capsulatum is a soil fungus that infects healthy mammalian hosts upon inhalation. Extrapolating from previous work, we hypothesized thatsmall-molecule natural products produced by Histoplasma are enriched for activity against host molecular targets. Using a bioinformatics approach, weidentified biosynthetic gene clusters in strain G217B containing genes required for natural product synthesis in other organisms: nonribosomal peptidesynthetases (NPS) and polyketide synthases (PKS). Experimentally, we found that partially purified compounds from Histoplasma culture supernatants areable to buffer supernatants against acidic challenge and promote macrophage lysis. Both activities are relevant to virulence in mammalian hosts. We arestructurally characterizing the relevant natural products using preparative HPLC, MS and NMR. In a complementary approach, we used RNA interferenceto target the complete set of NPS and PKS genes identified in the Histoplasma genome. We are using the resultant mutant strains to correlate biosyntheticgenes with small molecule production, and to assess the role of these genes in pathogenesis.605. From antagonism to synergism: roles of natural phenazines in bacterial-fungal interactions between Pseudomonas aeruginosa and Aspergillusfumigatus. He Zheng 1 , Fangyun Lim 2 , Jaekuk Kim 1 , Mathew Liew 1 , John Yan 1 , Neil Kelleher 1 , Nancy Keller 2 , Yun Wang 1 . 1) Northwestern University,Evanston, IL, USA; 2) University of Wisconsin-Madison, Madison, WI, USA.Secreted small molecules are increasingly recognized to mediate many types of bacterial-fungal interactions in nature and the clinical environment,27th Fungal Genetics Conference | 269