Program Book - 27th Fungal Genetics Conference

FULL POSTER SESSION ABSTRACTSbinding module, 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.248. Genomic context and distribution of effector genes in Fusarium oxysporum. Sarah Maria Schmidt 1 , Peter van Dam 1 , Petra M. Houterman 1 , InesSchreiver 2 , Lisong Ma 1 , Stephan Amyotte 3 , Biju Chellappan 1 , Sjef Boeren 4 , Frank L.W. Takken 1 , Martijn Rep 1 . 1) Molecular Plant Pathology, SwammerdamInstitute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, the Netherlands; 2) Fachgebiet Medizinische Biotechnologie,Institut für Biotechnologie, Technische Universität Berlin, Gustav-Meyer-Allee 25, Germany; 3) Department of Plant Pathology, University of Kentucky,201F Plant Science Building, 1405 Veterans Drive, Lexington, KY 40546-0312, USA; 4) Laboratory for Biochemistry, Wageningen University, Dreijenlaan 3,6703HA, Wageningen, the Netherlands.Strains of the Fusarium oxysporum species complex (FOSC) are able to infect a wide range of mono- and dicotyledonous plants. Based on the hostspecificity of individual strains, the FOSC is divided into various formae speciales. All strains share a common core genome and possess additional lineagespecific(LS) chromosomes. The fungus secretes effector proteins into the host vascular system that presumably manipulate the host to promote infection.In the tomato pathogen F. oxysporum f. sp. lycopersici (Fol) these effectors are encoded by SIX (Secreted In Xylem) genes. Interestingly, all SIX genes arepresent on a single LS chromosome that can be transferred horizontally to a previously non-pathogenic Fo strain, resulting in gain of pathogenicity towardstomato. Upon close inspection of this tomato pathogenicity chromosome we discovered that a non-autonomous miniature transposable element (mite) ispresent in the promoters of all SIX genes. Promoter deletion analysis at two different SIX gene loci did not reveal a direct role of the mite for SIX geneexpression. However, we were able to use this genomic signature to predict novel effector gene candidates in the Fol genome. Expression of several ofthese novel candidates during infection was confirmed by mass spectroscopic analysis of the xylem sap of Fol-infected tomato plants. We also discovered asmall reservoir of ‘silent’ effector genes that are not expressed during infection. Next, we used our method to predict effector gene candidates in thegenomes of several other formae speciales and developed a more global picture of the effector gene complement in the FOSC. Effector genes in Foconsistently reside in repeat-rich enviroments. Some strains contain 2 or 3 paralogs of an effector gene. Additionally, many genomes feature truncatedeffector gene homologs. Overall, the effector gene distribution among different formae speciales is patchy, and there is no unique set of effectors that iscommon to all plant pathogenic strains of the FOSC.249. Whole genome sequencing reveals new links between diverse plant pathogens; an expanded AvrLm6-like gene family in Venturia species. JasonShiller 1 , Angela van de Wouw 2 , Dan Jones 1 , Joanna Bowen 3 , Carl Mesarich 3 , Matthew Templeton 3 , Kim Plummer 1 . 1) La Trobe University, Melbourne,Australia; 2) University of Melbourne, Melbourne, Australia; 3) Plant and Food Research, Auckland, New Zealand.Venturia inaequalis and V. pirina are hemi-biotrophic fungi that cause apple scab and pear scab, respectively. These diseases cause significant losses togrowers worldwide. In some cases, scab is controlled with resistant cultivars, but fungicides are more commonly used. Resistance to scab follows the genefor-genemodel, whereby a gene coding for a resistance protein in the host will have a cognate gene coding for an avirulence protein (or effector) in thefungus. No Venturia effectors have been characterised to date, but work is underway to identify effectors from the whole genome sequences and secretedproteins of V. inaequalis and V. pirina. Whole genome sequencing of Venturia inaequalis and V. pirina has revealed predicted proteins with some sequencesimilarity to AvrLm6, a Leptosphaeria maculans effector that triggers resistance in Rlm6 canola. The mechanism of action of AvrLm6 is unknown. Untilrecently, AvrLm6 was thought to be unique to L. maculans, with orthologues absent, even in closely related species. AvrLm6-like genes from Venturia sppwhose genomes are sequenced form large families containing up to 30 members. We have also identified orthologues in F. oxysporum (Fo5176) and C.higginsianum from public database searches. Gene expansions have also been observed for other effector-like genes in the Venturia genomes. TheAvrLm6-like predicted protein from V. inaequalis, with the highest sequence identity to AvrLm6, was unable to trigger a resistance response in Rlm6canola. However, this does not preclude the AvrLm6-like proteins from being functionally active in the Malus-Venturia pathosystem. Transcriptomeanalyses (RNA-seq) of in planta and in vitro samples of V. inaequalis have revealed that a number of AvrLm6-like genes are up-regulated during infection(compared to growth in vitro). These results were confirmed with qRT-PCR. The most highly up-regulated predicted protein, ALVi_149, was tagged withYFP. YFP expression was observed only in the sub-cuticular stromata (specialised, biotrophic infection structures). RNA silencing is currently underway todetermine the role of ALVi_149 in pathogenicity of V. inaequalis. The major question that remains is; what purpose do these genes serve for these diversefungi and what is driving the gene expansions in Venturia spp?250. Oömycetes Protein Array Project. Samantha Taylor 1 , Regina Hanlon 2 , Mandy Wilson 2 , Jean Peccoud 2 , Brett Tyler 1 . 1) Oregon State University,Corvallis, OR; 2) Virginia Tech, Blacksburg, VA.Oömycetes are eukaryotes that outwardly resemble fungi, but are related to brown and golden-brown algae. The most destructive oömycete genus isPhytophthora, with over 80 species that collectively attack a wide range of plant species, causing damage to crops that is estimated in billions of dollarsannually in the US. The goal of the Oömycetes Protein Array Project is to generate a collection of cloned proteins from 1440 predicted oömycete effectorsequences, to use Gateway® technology to facilitate the easy transfer of clones into expression vectors, and to make the resulting clones available to thescientific community for further research. When the project is over, the final collection should include 390 clones from P. sojae, 550 clones from P.infestans, 370 clones from P. ramorum, and 130 clones from H. arabidopsidis.251. Extensive chromosomal reshuffling drives evolution of virulence in an asexual pathogen. Ronnie de Jonge 1,2 , Melvin Bolton 3 , Anja Kombrink 1 , KosteYadeta 1 , Grardy van den Berg 1 , Bart Thomma 1 . 1) Laboratory of Phytopathology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, TheNetherlands; 2) VIB Department of Plant Systems Biology, Ghent University, Bioinformatics and Evolutionary Genomics Division, Technologiepark 927, B-9052 Gent, Belgium; 3) United States Department of Agriculture, Agricultural Research Service, Northern Crop Science Laboratory, Fargo, ND 58102-2765,United States.Sexual recombination drives genetic diversity in eukaryotic genomes, and fosters adaptation to novel environmental challenges. Although strictly asexualmicroorganisms are often considered as evolutionary dead ends, they comprise many devastating plant pathogens. Presently, it remains unknown howsuch asexual pathogens generate the genetic variation that is required for quick adaptation and evolution in the arms race with their hosts. Here we showthat extensive chromosomal rearrangements in the strictly asexual plant pathogenic fungus Verticillium dahliae establish highly dynamic ‘plastic’ genomicregions that act as a source for genetic variation to mediate aggressiveness. We show that these plastic regions are greatly enriched for in plantaexpressedeffector genes, encoding secreted proteins that enable host colonization including the previously identified race 1-specific effector Ave1 thatactivates Ve1-mediated resistance in tomato. The plastic regions occur at the flanks of chromosomal breakpoints and are enriched for repetitive sequenceelements, especially retrotransposons. Our results demonstrate that asexual pathogens may evolve by prompting chromosomal rearrangements, enabling182