Program Book - 27th Fungal Genetics Conference

FULL POSTER SESSION ABSTRACTSin the Neurospora genome. We have assayed the activation by light of the Neurospora homologs of A. nidulans conidiation genes (flbA, flbC, flbD, medAand stuA), and the Neurospora conidiation gene con-10 as a control. Unlike con-10, none of the Neurospora homologs of the A. nidulans conidiation geneswere induced by light in vegetative mycelia. However, we found that deletion fl resulted in light-dependent mRNA accumulation for all the conidiationgenes. This result indicated that the absence of FL allows the binding of the WC complex to the promoter of these genes to activate transcription in a lightdependentmanner. We have assayed the amount of WC proteins in the Dfl and wild type strains but we did not find any difference between the twostrains. We expect to identify additional genes deregulated by the absence of FL after massive sequencing of total RNA (RNAseq) using a Dfl strain andwild-type strain in dark and light conditions. We have investigated the role of FL during conidiation in Neurospora using a tagged version of FL. FL ispresent in vegetative mycelia but the amount increses after light exposure. We observed several forms of FL due to phosphorylation, and and we havedetermined by mass spectrometry that FL is phosphorylated in several residues. We have immunoprecipitated FL to identify proteins that may interactwith FL. We have found a protein that interacts with FL in different growth conditions. This protein has been described in other organisms and plays a rolein the ability to grow in the presence of trehalose. Since FL is a transcription factor, we have use FL::3XFLAG strain to do ChIPseq in order to identify theputative binding sites of FL to the DNA. We expect that the results from these experiments will help us to understand in more detail the role of FL in theactivation of gene transcription during development.447. Transcriptomic profiling of fumonisin B biosynthesis by Fusarium verticillioides. N. Ponts, E. Zehraoui, L. Pinson-Gadais, F. Richard-Forget, C.Barreau. INRA, UR1264-MycSA, 71 avenue Edouard Bourlaux, BP81, F-33883 Villenave d’Ornon, France.The plant fungal pathogen Fusarium verticillioides can infect various plants worldwide, including maize, and contaminate kernels with mycotoxins of thefumonisin family. Fumonisins B are stable polyketides that resist agrifood processing and are classified as potentially carcinogenic. As such, contaminationof food and feeds with these toxic secondary metabolites must be avoided. Numerous factors influence fumonisins B accumulation on maize, including thecomposition of the grains on which Fusarium develops. In particular, several phenolic compounds were shown to inhibit fumonisin B biosynthesis.Preliminary analyses showed that free phenolic acids are particularly abundant in immature grains, i.e., at the onset of toxin production, from cerealcultivars on which mycotoxins tend to accumulate less. We tested in vitro the effect of chlorogenic, caffeic, and ferulic acid on fumonisin B production in F.verticillioides. All three compounds inhibit fumonisin B accumulation, caffeic acid being the most efficient with that regard. We investigated themechanisms by which these phenolic acids may exert their inhibitory properties and analyzed whole genome expression levels by RNA-seq. Sequencedreads were mapped to the reference genome of F. verticillioides and results were analyzed according to the current annotation available at the FusariumComparative Database. Doing so, we identified 175 and 1133 potential new genes and transcripts, respectively. We also found that the genes involved inthe fumonisins biosynthetic pathway are all inhibited in the presence of any of the three tested phenolic acids. Finally, we identified sets of genes that areregulated specifically by a given phenolic acid, and others that follow similar patterns in all tested conditions. As a whole, our results show a large reorganizationof Fusarium’s transcriptome upon phenolic acid treatment.448. Differential transcriptome analysis of Zymoseptoria tritici infecting wheat reveals novel effectors. Stefano F.F. Torriani 1 , Marcello Zala 1 , DanielCroll 1 , Patrick C. Brunner 1 , Eva H. Stukenbrock 2 , Dee Carter 3 , Bruce A. McDonald 1 . 1) Integrative Biology, ETHZ, Zurich, Switzerland; 2) Max Planck Institutefor Terrestrial Microbiology, Marburg, Germany; 3) University of Sydney, Sydney, Australia.Zymoseptoria tritici (formerly called Mycosphaerella graminicola) is a hemibiotrophic fungus belonging to the Dothideomycetes, the largest class ofascomycetes that includes many plant pathogens. Like other hemibiotrophic pathogens Z. tritici uses different strategies for obtaining nutrition during itslife cycle. For the first 10 days post inoculation (dpi) the pathogen colonize the host as a biotroph without causing visible symptoms. The necrotrophicphase lasts until the affected plant cells have died. Depending on the strain-cultivar interaction, plant cell death occurs from 18 to 20 days afterpenetration. Z. tritici concludes its life cycle by surviving as a saprotroph on dead leaves for several months. Thus Z. tritici presents a powerful system tostudy host-pathogen interactions during different stages of disease development. Next generation sequencing technology was used to analyze changes intranscription during the complete infection cycle of Z. tritici on wheat. The total RNA was extracted from inoculated plants at six time points (3-, 7-, 11-,14-, 21- and 56- dpi). RNA-Seq analyses allowed us to trace the expression profile of 10,251 genes and identify genes that differed in expression betweenthe biotrophic, necrotrophic and saprotrophic stages of infection. About 14% and 34% of the genes showed statistically significant differences inexpression from the biotrophic to necrotrophic and from the necrotrophic to saprotrophic stages of infection, respectively. Putative effector genes werepreferentially transcribed at 11 dpi during the transition between biotrophy and necrotrophy. Through this screen we identified five putative effectorgenes for further characterization, using Agrobacterium-mediated transformation to determine their role in pathogenicity. Although recent experimentalefforts focused mainly on proteinaceous effectors, we investigated the role of non-proteinaceous metabolites as they can also manipulate host cells. Twodifferent clusters of genes (PKS4 and PKS5-related genes) involved in the biosynthetic pathways of different secondary metabolites showed expressionpatterns similar to the putative effectors. Confirmation of function of the putative virulence genes will be based on gain or loss of virulence in planta usinggene knock-outs and knock-ins.449. Role of the xprG gene in autolysis, secondary metabolism and asexual development in Aspergillus nidulans . Margaret E. Katz, KatharynBraunberger, Sarah Cooper. Dept Molec & Cellular Biol, Univ New England, Armidale, Australia.The Aspergillus nidulans xprG gene encodes a transcriptional activator that is a member of the Ndt80 family in the p53-like superfamily of proteins.Previous studies have shown that XprG controls the production of extracellular proteases in response to starvation. We undertook transcriptional profilingto investigate whether XprG has a wider role as a global regulator of the carbon nutrient stress response. Our microarray data showed that the expressionof a large number of genes, including genes involved in secondary metabolism, development, and autolysis, were altered in an xprGD null mutant. Many ofthese genes are known to be regulated in response to carbon starvation. We confirmed that sterigmatocystin and penicillin production is reduced in xprGmutants.The loss of fungal mass and secretion of pigments that accompanies fungal autolysis in response to nutrient depletion was accelerated in anxprG1 gain-of-function mutant and decreased or absent in an xprG- mutant. We found that conidophore development occurred in carbon-starvedsubmerged cultures of both the xprGD1 loss- and xprG1 gain-of-function mutants, though the number of metulae appeared to be reduced. Thus, thereduction of brlA expression observed in the xprGD1 mutant is not sufficient to block conidiophore development in response to carbon starvation. .However, the xprG1 gain-of-function mutation partially suppresses VeA-mediated repression of conidiophore development and the conidiophoredevelopment defect in the fluG701 mutant. These results support the hypothesis that XprG plays a major role in the response to carbon limitation and thatnutrient sensing may represent one of the ancestral roles for the p53-like superfamily.450. Fugal-specific sirtuin HstD coordinates the secondary metabolism and development via the LaeA. M. Kawauchi 1,2 , K. Iwashita 1,2 . 1) Dept. Mol.Biotech., Grad. Sch. Adv. Sci. Mat., Hiroshima Univ., Hiroshima, Japan; 2) Natl. Res. Inst. Brewing, Hiroshima, Japan.27th Fungal Genetics Conference | 231