Program Book - 27th Fungal Genetics Conference

FULL POSTER SESSION ABSTRACTSSeq data did not substantiate a mating dependent expression for those genes. To get more insights into the function an over expression of the gene brl2under control of tef1-promoter was performed. Phenotypes of independent mutants showed no hints for a faster mating, changes in clamp formation ornuclear distribution tested by mating experiments. Only an asymmetric distribution of fruiting bodies was visible, which seems to originate from thedifferent protein background respectively epigenetics of the two partners just before mating interaction and dikaryotization. Tagging of the receptors forvisualization is planned, which will lead to more knowledge about localization and putative interacting proteins.204. Characterization of new STRIPAK complex interaction partners in the filamentous ascomycete Sordaria macrospora. Britta Herzog, YasmineBernhards, Berit Habing, Eva Reschka, Sabine Riedel, Stefanie Pöggeler. Institute of Microbiology and Genetics, Department of Genetics of EurkaryoticMicroorganisms, Georg-August-University Göttingen, Germany.Using Sordaria macrospora as model organism we investigate the complex process of fruiting-body development and involved proteins in thisfilamentous ascomycete. This differentiation process is regulated by more than 100 developmental genes. Recently, we have shown that a homologue ofthe human STRIPAK (striatin-interacting phosphatase and kinase) complex engages a crucial role in sexual development in fungi. The S. macrospora striatinhomologue PRO11 and its interaction partner SmMOB3 are key components of this complex (Bloemendal et al., 2012). PRO11 contains a conserved WD40repeat domain and is supposed to function as scaffolding protein linking signaling and eukaryotic endocytosis (Pöggeler and Kück, 2004). SmMOB3(phocein) is a member of the MOB family (Bernhards and Pöggeler, 2011). Beside their important role in multicellular development and hyphal fusion bothproteins seem to be involved in vesicular trafficking and endocytosis.By means of yeast two-hybrid screens and GFP-Trap analysis we identified several new interaction partners of PRO11 and SmMOB3. Similar to PRO11and SmMOB3, a multitude of them are predicted to be involved in vesicular trafficking and are localized to the ER or to the Golgi. Here, we show theresults of a detailed analysis of the new STRIPAK complex interaction partners. Initially, we isolated the cDNA of the genes and confirmed the interactionby yeast two-hybrid. For further characterization and to get knowledge about their cellular functions we created knock-out strains and analyzed theirmorphological phenotypes. For localization and expression studies we constructed EGFP-tagged fusion proteins and expressed them in S. macrospora.Bernhards and Pöggeler, 2011; Curr Genet 57 (2): 133-49.Bloemendal et al., 2012; Mol Microbiol 84 (2): 310-23.Pöggeler and Kück, 2004; Eukaryot Cell 3 (1): 232-40.205. Hypocrea jecorina meiosis generates segmentally aneuploid progeny to enhance production of xylan-degrading hemicellulases. T.-F Wang, C.LChen, P. W.-C. Hsu, W.-C. Li, S.-Y. Tung, C.-L. Wang, H.-C. Kuo. Institute of Molecular Biology, Academia Sinica, Taipei, TaiwanI.Hypocrea jecorina is the sexual form of Trichoderma reesei, an industrially important cellulolytic filamentous fungus. We report that H. jecorina meiosisutilizes a novel Ku70-dependent duplication mechanism to generate segmentally aneuploid progenies, thus increasing the diversity of genotypes andensuring more efficient xylan degradation. H. jecorina sexual reproduction yields hexadecad asci with 16 linearly arranged ascospores. Our results indicatethat these ascospores are generated via two rounds of postmeiotic mitosis following the two meiotic divisions. Remarkably, the hexadecad asci frequently(>90%) contain four or eight inviable ascospores with an equal number of viable segmentally aneuploid ascospores. Array-based comparative genomichybridization revealed that all the viable segmental aneuploid progenies have a large chromosomal duplication (~0.5Mbp). Deletion of thenonhomologous end-joining gene ku70 restores canonical meiosis and 16 viable euploid ascospores. Segmental duplication contains genes involved inxylan degradation and enhances expression of several carbohydrate-active enzymes, particularly cell wall degrading hemicellulases.206. Deletion of MAT 1-2-1 gene results in mating type switching in Ceratocystis fimbriata. P. Markus Wilken 1 , Emma T. Steenkamp 2 , Mike J. Wingfied 1 , Z.Wilhelm de Beer 2 , Brenda D. Wingfield 1 . 1) Dept Genetics, University of Pretoria, Pretoria, Gauteng, South Africa; 2) Dept Microbiology and PlantPathology, University of Pretoria, Pretoria, Gauteng, South Africa.Sequencing of the Ceratocystis fimbriata genome has made it possible to consider the long standing question as to how uni-directional mating typeswitching functions in this fungal pathogen and its relatives. Uni-directional mating type switching was first observed in the homothallic ascomycete C.fimbriata in the 1960’s. Two forms of progeny arise after meiosis, some self-fertile and thus not requiring an opposite mating partner to complete thesexual cycle. Other isolates are self-sterile and unable to reproduce sexually. This loss of self-fertility has been shown to be associated with the loss of afragment of the mating specific gene, MAT1-2-1, in self-sterile strains. The aim of this study was interrogate the full genome sequence of C. fimbriata todetermine whether the full MAT1-2-1 gene is deleted and whether other MAT genes are affected during mating type switching. We were able todetermine that C. fimbriata has both the MAT1-2-1 gene and the MAT1-1 genes (MAT1-1-1 and MAT1-1-2). The self-sterile isolates had only lost theMAT1-2-1 gene and one copy of a 230 base pair perfect repeat which flanks this gene in the self fertile isolates. The loss of the entire MAT1-2-1 geneexplains the loss of fertility and the repeats are suggestive of the involvement of recombination during the deletion event. This study illustrates a uniquemating strategy in the fungi, not previously understood at the molecular level. The newly gained knowledge will also make it possible to consider themechanisms underpinning uni-directional switching in other species of Ceratocystis.207. Mannitol is essential for the development of stress resistant ascospores in Neosartorya fischeri. Timon T. Wyatt 1 , M.R. van Leeuwen 1 , H.A.B.Wösten 2 , J. Dijksterhuis 1 . 1) Applied and Industrial Mycology, CBS-KNAW Fungal Biodiversity Centre, Utrecht, the Netherlands; 2) Microbiology, UtrechtUniveristy, Utrecht, the Netherlands.The sugar alcohol mannitol is one of the main compatible solutes in Neosartorya fischeri and accumulates especially in conidia and ascospores. In fungi,mannitol has been implicated in a wide variety of functions including carbon storage, maintaining reduction potential, water absorption, heat stressprotection, protection against oxidative stress, and tolerance against osmotic stress. Biosynthesis of mannitol in ascomycota mainly depends on mannitol1-phosphate dehydrogenase (MPD). In our study a functional analysis was performed of the MPD encoding gene mpdA of N. fischeri. The fluorescenceproteins GFP and dTomato were put under control of the mpdA promoter. Expression of mpdA was observed in aerial hyphae and conidiophores, but wasespecially high in ascomata and ascospores. Disruption of mpdA reduced mannitol as much as 85% of the wild type and increased trehalose levels to morethan 400%. Decreased mannitol accumulation had no obvious effect on mycelium growth when exposed to temperature and oxidative stress, while anincreased stress sensitivity of conidia against heat and oxidative stress was observed. The most distinct phenotype of mpdA disruption was the completeabsence of ascospores. Formation of fruiting bodies (ascomata) and asci was not affected but the developmental defect was shown to occur after meiosis.Similar results were obtained by adding the MPD inhibitor nitrophenide to the wild-type strain. Our result suggest a role of mannitol as carbon storagemolecule during sexual development, but also its role as scavenger of hydroxyl radicals can be of importance for the formation of sexual spores. Mannitolmight regulate the Reactive Oxygen Species (ROS) levels induced by Nox (NADPH oxidases) family enzymes during sexual development. Taken together,27th Fungal Genetics Conference | 171