Program Book - 27th Fungal Genetics Conference

FULL POSTER SESSION ABSTRACTSdecreased. Northern blot analysis revealed that the expression of cbhIb decreased in the clbRox strain under cellulose inducing condition. However, theclbR overexpression increased xynIa expression under wheat bran inducing condition, but not under the avicel inducing condition. The effect of the clbRoverexpression was not equal to the enzyme production and the gene expression even though they were under the control of ClbR. These results suggestthat ClbR coordinately controls their expression with another factors.374. Regulation of the a-tubulin B-encoding gene during early development of the phytopathogenic fungus Botrytis cinerea. Y. Faivre Talmey 1 , I. R.Gonçalves 1 , A. Simon 2 , M. Viaud 2 , C. Bruel 1 . 1) CNRS, University Claude Bernard, LYON, France; 2) INRA, BIOGER, Grignon, France.The fungal plant pathogen Botrytis cinerea is able to infect more than 250 different hosts and is responsible for major economic losses worldwide. Thesuccess of the fungus life cycle relies on distinct developmental stages and specific cellular structures like appressoria, infection cushions, conidiophores,apothecia and sclerotia. Based on the important role that cytoskeleton plays in cellular organization and shape in all eucaryotes, attention was given totubulins and their putative specific role in the virulence of B. cinerea. One b-tubulin and two a-tubulin encoding genes are found in B. cinerea‘s genome.Alpha-tubulin A and B share 69% identity at the protein level and phylogenetic analyses revealed that orthologs to the a-tubulin A gene exist in allascomyceta species whereas the a-tubulin B gene seems to be present in some ascomyceta only. Expression studies showed that the a-tubulin B gene ismore expressed than the a-tubulin A gene. Besides, a peak of expression is observed for the a-tubulin B encoding gene early during conidia-derived fungaldevelopment. In order to understand the regulation of the a-tubulin B encoding gene, combinations of promoter deletions and transcriptional fusionswere used. Putative regulatory regions were identified and the one hybrid yeast system was used to search for putative transcription factors that wouldinteract with these regions and play a role in the regulation of this gene.375. The regulation of D-galacturonic acid utilization in Botrytis cinerea. Lisha Zhang, Joost Stassen, Sayantani Chatterjee, Maxim Cornelissen, Jan vanKan. Laboratory of Phytopathology, Wageningen University, Wageningen, Netherlands.The plant cell wall is the first barrier to pathogen invasion. The fungal plant pathogen Botrytis cinerea produces a spectrum of cell wall degradingenzymes for the decomposition of host cell wall polysaccharides and the consumption of the monosaccharides that are released. Especially pectin is animportant cell wall component, and the decomposition of pectin by B. cinerea has been extensively studied. D-galacturonic acid is the most abundantcomponent of pectin and effective utilization of D-galacturonic acid is important for virulence of B. cinerea. The D-galacturonic acid catabolic pathwaycomprises three enzymatic steps, involving D-galacturonate reductase (encoded by Bcgar1 and Bcgar2), L-galactonate dehydratase (encoded by Bclgd1),and 2-keto-3-deoxy-L-galactonate aldolase (encoded by Bclga1). Therefore, an effective concerted action of the appropriate pectin depolymerisingenzymes, monosaccharide transporters and catabolic enzymes is important for complete pectin utilization by B. cinerea. In this study, RNA sequencing wasperformed to compare genome wide transcriptional profiles in B. cinerea grown in media containing glucose and pectate as sole carbon sources. Weidentified 31 genes that are significantly upregulated in pectate containing culture, including Bcgar2, Bclga1, and a putative monosaccharide transporter.In addition, conserved cis-regulatory elements were predicted in the promoters of genes involved in pectate decomposition and D-galacturonic acidutilization. Functional analysis was carried out of the bidirectional promoter of the Bcgar2-Bclga1 gene cluster to study which of the cis-regulatoryelements is required for induction by D-galacturonic acid. Furthermore, potential regulatory protein(s) were isolated by DNA-protein pull down assaysusing one important cis-regulatory element.376. Epigenetic Regulation of Subtelomeric Gene Noise in Candida albicans. Matthew Z Anderson, Joshua A Baller, Lauren J Wigen, Judith Berman.Genetics, Cell Biology and Development, Univeristy of Minnesota, St Paul, MN.Candida albicans grows within a wide range of fluctuating host niches, and the ability to rapidly adapt enhances its success as a commensal and as apathogen. The recently expanded telomere-associated (TLO) gene family consists of fourteen expressed members in C. albicans. Each TLO gene encodes aparalog of a single Mediator complex component. Thirteen expressed TLOs are located at the chromosome ends as the most telomere-proximal openreading frame. Individual TLO expression at both the transcript and protein level was extremely noisy. Noise originated from single cell variability in TLOexpression due to intrinsic factors. Deletion of chromatin modifying enzymes that function in subtelomeric silencing abolished TLO noise, as did ectopicallyexpressing a TLO from an internal locus. Conversely, transcriptional variation of a low noise gene increased significantly when ectopically expressed in thesubtelomere. Interestingly, deletion of the Mediator component MED3, which inhibits Tlo from incorporating into Mediator, also drastically reduced TLOnoise and supports an autoregulatory mechanism for TLO noise. These data suggest subtelomeric chromatin structure regulates TLO gene noise throughthe action of chromatin modifiers and Mediator. We propose that TLO noise is beneficial to C. albicans by producing heterogeneous cell populations thatincorporate different Tlo proteins in Mediator, producing a range of transcriptional profiles in the population that allows some cells to survive in alteredenvironmental conditions.377. Signaling and Cell Behavior: Pheromone Response in Candida albicans. Ching-Hsuan Lin 1,2 , Kabrawala Shail 2 , Fox Emily 3 , Nobile Clarissa 3 , JohnsonAlexander 3 , Bennett Richard 2 . 1) Dept. Biochem. Sci. and Tech., NTU, Taipei, Taiwan; 2) Dept, MMI, Brown Univ. RI; 3) Dept, Biochem. Biophy. UCSF, CA.Candida albicans is currently the most common human fungal pathogen, and its propensity for causing infection has been closely lined with its ability toform biofilms. Central to understanding its behavior is the white-opaque phenotypic switch, in which cells can undergo an epigenetic transition betweenthe white state and the opaque state. The phenotypic switch regulates multiple properties including biofilm formation, virulence and sexual mating. Inparticular, opaque cells are the mating competent form whereas white cells do not mate but generate biofilms in response to pheromone. In this work, weidentify the master transcriptional regulator involved in pheromone-induced biofilms in white cells as well as sexual mating in opaque cells as C. albicansCph1, ortholog of Saccharomyces cerevisiae Ste12. In contrast, Cph1 is not required for the formation of conventional biofilms (biofilms that can formwithout pheromone treatment). Transcriptional profiling analysis under biofilm conditions during pheromone treatment revealed a number of potentialdownstream targets of Cph1 and Tec1. In total, we observed 23 genes that exhibited decreased induction (>2-fold) by pheromone in both Dcph1 and Dtec1mutants. Of these genes, six candidates were chosen for further analysis due to their dependence on Cph1 and Tec1 for pheromone-induced expression,and because they were also not induced in pheromone-treated opaque cells. Interestingly, one novel gene product shown to influence biofilm formation isHgc1. Similar to the Dtec1, deletion of HGC1 resulted in decreased biofilm formation in white cells responding to pheromone, and also abolished formationof conventional biofilms. It is therefore apparent that Hgc1 is important for cell adhesion and biofilm development in the two distinct models of biofilmformation. Most importantly, these results suggest that both shared and unique components operate in different models of biofilm formation in thisimportant human pathogen.378. Transcriptional regulatory networks controlling the early hypoxic response in Candida albicans. A. Nantel, M. van het Hoog, A. Sellam, C.Beaurepaire, F. Tebbji, M. Whiteway. National Research Council of Canada, Montreal, Quebec, Canada.212