Program Book - 27th Fungal Genetics Conference

CONCURRENT SESSION ABSTRACTSGenome-wide analysis of eleven white- and brown-rot Polyporales provides insight into mechanisms of wood decay. Chiaki Hori 1,2 , Kiyohiko Igarashi 1 ,David Hibbett 3 , Bernard Henrissat 4 , Masahiro Samejima 1 , Dan Cullen 2 . 1) Graduate School of Agricultural and Life sciences, University of Tokyo, Tokyo,Japan; 2) Forest Products Laboratory, USDA, Madison, WI; 3) Biology Department, Clark University, Worcester, MA; 4) CNRS, Marseille, France.Many efficient wood decay fungi belong to the Polyporales, and these can be categorized as white-rot fungi or brown-rot fungi, based on decay patterns.White-rot fungi degrade cell wall polysaccharides such as cellulose and hemicellulose as well as the more recalcitrant phenylpropanoid polymer, lignin. Incontrast, brown-rot fungi depolymerize the polysaccharides but the modified lignin remains in the wood. Comparative analysis of white- and brown-rotgene repertoires and expression profiles have revealed substantial variation but considerable uncertainty persists with respect to precise mechanisms.Addressing this issue, we performed genome-wide analysis of carbohydrate-active enzymes (CAZy) and some oxidative enzymes related to polysaccharidesdegradation in eleven white- and brown-rot fungi. This analysis included classifying and enumerating genes from three recently sequenced polyporalesBjerkandera adusta, Ganoderma sp. and Phlebia brevispora. Furthermore, comparative secretomic analysis of seven Polyporales grown on wood culturewere conducted. Summarizing, the average number of genes coding CAZy in the genomes of white-rot fungi was 373, significantly more than the 283observed in brown-rot fungi. Notably, white-rot fungi have genes encoding cellulase and hemicellulase such as those belonging to glycoside hydrolase (GH)families 6, 7, 9 and 74, whereas these are lacking in genomes of brown-rot polyporales. White-rot genes encoding oxidative enzymes potentially related tocellulose degradation such as cellobiose dehydrogenase (CDH), polysaccharides monooxygenase (PMO, formerly GH61), cytochrome b562 with cellulosebindingmodule, are also increased relative to brown-rot fungi. Indeed, secretomic analysis identified GH6, GH7, CDH and PMO peptides only in white-rotfungi. Overall, these results show that, relative to brown rot fungi, white rot polyporales maintain greater enzymatic diversity supporting lignocelluloseattack.Transcription factor shuttling during cellulase induction in Trichoderma reesei. Alex Lichius, Christian P. Kubicek, Verena Seidl-Seiboth. Institute ofChemical Engineering, Vienna University of Technology, Vienna, Austria.For economically feasible production of liquid fuels and other value-added compounds from lignocellulosic plant material, strategies are required toboost cellulolytic and hemicellulolytic enzyme production by industrially relevant fungi. One promising approach is to modulate the transcriptional controlmediating release from carbon catabolite repression (CCR) and induction of cellulase, hemicellulase and xylanase gene expression. To better understandthe underlying molecular dynamics during induction, we characterized nucleo-cytoplamic shuttling of the two transcription factors carbon cataboliterepressor 1 (CRE1) and xylanase regulator 1 (XYR1) of Trichoderma reesei by means of live-cell imaging. In submerged cultures, nuclear import and exportof CRE1 upon repression and induction, respectively, occurred within minutes and therefore was generally faster than shuttling of XYR1. Under CCRconditions XYR1 expression levels were very low, and its nuclear signal required up to one hour to significantly increase upon replacement into an inducingcarbon source. Cultured directly under inducing conditions, nuclear accumulation of XYR1 was detectable after about 20h post inoculation, and stronglyincreased within the following 24 hours. CRE1 under the same conditions was localized exclusively to the cytoplasm. In plate cultures, nuclear recruitmentof CRE1 and XYR1 differed within the central area, the subperiphery and the periphery of the colony depending on the provided carbon source. Mostinterestingly, under inducing conditions we found evidence for increased nuclear recruitment of CRE1 in the central area, correlating with strong nuclearimport of XYR1 in the same region. Notably, the cytoplasmic signal of CRE1 was usually elevated in leading hyphae, whereas XYR1 was never significantlyrecruited to the colony periphery. Taken together our data provide the first temporal resolution of transcription factor shuttling during the induction ofcellulase gene expression in Trichoderma reesei, and reveal some interesting differences between the subcellular localization of CRE1 and XYR1 insubmerged and plate cultures, respectively. These differences indicate that the mycelial organization during fungal growth might be another importantregulatory element to consider for the industrial scale production of cellulolytic enzymes.27th Fungal Genetics Conference | 63