Program Book - 27th Fungal Genetics Conference

FULL POSTER SESSION ABSTRACTS260. The mitochondrial genomes of Fusarium circinatum, F. verticillioides and F. fujikuroi are unexpectedly similar. G Fourie 1 , N.A. van der Merwe 2 , B.D.Wingfield 2 , B. Tudzynski 3 , M.J. Wingfield 1 , E.T. Steenkamp 1 . 1) Department of Microbiology and Plant Pathology, Forestry and Agricultural BiotechnologyInstitute (FABI), University of Pretoria. Pretoria, South Africa; 2) Department of Genetics, Forestry and Agricultural Biotechnology Institute (FABI),University of Pretoria, Pretoria, South Africa; 3) University of Munster, Germany.The Gibberella fujikuroi species complex consists of species that are of considerable agricultural, medical and veterinary importance. Nevertheless, manyof the relationships among species in this complex remain largely unresolved, irrespective of the markers employed. In this study, we considered thefeasibility of using mitochondrial genes to resolve the higher level evolutionary relationships of the species in the complex. Because there is limitedinformation available regarding the structure and evolution of mitochondrial genomes in the G. fujikuroi species complex, we fully characterized themitochondrial genomes of the representative species; Fusarium circinatum, F. verticillioides and F. fujikuroi. Overall, the mitochondrial genomes of thethree species displayed a high degree of synteny, with all the genes in identical order and orientation. This similarity also extended to the intergenicregions, as well as introns that share similar positions within genes. The results show genome similarity beyond the expected characters common to themitochondrial genomes of the Sordariomycetes. The intergenic regions and introns generally contributed significantly to the size differences and diversityobserved among these genomes. Phylogenetic analysis of the concatenated protein-coding data set separated members of the G. fujikuroi complex fromother Fusarium species. The individual mitochondrial gene trees did not always support the phylogeny of the concatenated data set and at least six distinctphylogenetic trees were recovered. This incongruence could arise from biased selection on some genes or recombination among mitochondrial genomes,potentially linked to a hybridization event. The results suggest that using individual genes for phylogenetic inference could mask the true relationshipsbetween species in this complex.261. Comparative pathogenomics: next generation dissection of mechanisms of pathogenesis on plants. Donald M Gardiner 1 , Jana Sperschneider 3 , PaulaMoolhuijzen 4 , Matthew Bellgard 4 , Kemal Kazan 1 , Jen Taylor 2 , John Manners 2 . 1) Plant Industry, CSIRO, St Lucia, Queensland, Australia; 2) Plant Industry,CSIRO, Canberra, ACT, Australia; 3) Plant Industry, CSIRO, Perth, WA, Australia; 4) Centre for Comparative Genomics Murdoch University Perth, WesternAustralia, 6150.Comparative analyses between fungal plant pathogens that share a common host have revealed important mechanisms of virulence in a number ofdifferent systems. We have an interest in understanding how Fusarium pathogens of wheat and barley cause head blight and crown rot diseases on thesehosts. With modern genome sequencing technologies the power to undertake comparative analyses to assist in the understanding of key molecularmechanisms involved in pathogenesis has undoubtedly increased. We have recently sequenced an additional seven Fusarium isolates that are associatedwith wheat including isolates of F. equiseti, F acuminatum, F. culmorum and F. pseudograminearum and are using these in comparative analyses. Sequencebased homology searching between limited numbers of selected species have been particularly powerful in identifying signatures of horizontal transferbetween phylogenetically diverse species which have been an important force in the evolution of virulence and examples of these that we have shown tobe involved in virulence will be discussed. We are also developing methodologies to predict genes important in virulence that consider more remotehomologies between species that may represent structural and/or functional conservation which also consider phylogenetic distributions and enrichmentin species with particular lifestyles or shared plant hosts.262. Characterisation of stuA homologue in Fusarium culmorum. Matias Pasquali 1 , Francesca Spanu 2 , Virgilio Balmas 2 , Barbara Scherm 2 , Kim HammondKosack 3 , Lucien Hoffmann 1 , Marco Beyer 1 , Quirico Migheli 2,4 . 1) Environment and Agrobiotechnology Dept, CRP GABRIEL LIPPMANN, Belvaux, Luxembourg;2) Dipartimento di Agraria - Sezione di Patologia vegetale ed entomologia and Unità di ricerca Istituto Nazionale di Biostrutture e Biosistemi, Universitàdegli Studi di Sassari, Viale Italia 39, I-07100 Sassari, Italy; 3) Wheat Pathogenomics, Department of Plant Biology and Crop Sciences , RothamstedResearch, Harpenden, Herts AL5 2JQ, UK; 4) Centro interdisciplinare per lo sviluppo della ricerca biotecnologica e per lo studio della biodiversità dellaSardegna e dell'area mediterranea, Università degli Studi di Sassari, Viale Italia 39, I-07100 Sassari, Italy.Fusarium culmorum is one of the most harmful pathogens of durum wheat and the causal agent of foot and root rot (FRR) disease. F. culmorum producesdifferent trichothecene mycotoxins that are involved in the pathogenic process. The role of the gene FcStuA, a stuA ortholog protein with an APSESdomain sharing 98.5% homology to the FgStuA protein (FGSG10129), was determined by functional characterisation of deletion mutants obtained fromtwo F. culmorum wild-type strains, namely FcUK99 (a highly pathogenic trichothecene producer) and Fc233B (unable to produce toxin and with a mildpathogenic ability). The DFcStuA mutants originating from both strains showed common phenotypic characters including stunted vegetative growth, lossof mycelium hydrophobicity, altered pigmentation, decreased production of polygalacturonases, altered and reduced conidiation, delayed sporegermination patterns and complete loss of pathogenicity towards wheat stem base/root tissue. Toxin production in mutants originating from FcUK99strain was significantly decreased in vitro to 5% of the original production. Moreover, both sets of mutants were unable to colonise non-cereal planttissues, i.e. apple and tomato fruits and potato tubers. No differences between mutants, ectopic and wild-type strains were observed concerning the levelof resistance towards four fungicides belonging to three classes, the demethylase inhibitors epoxiconazole and tebuconzole, the succinate dehydrogenaseinhibitor isopyrazam and the cytochrome bc1 inhibitor trifloxystrobin. StuA is a global regulator in F. culmorum and is a potential target for novelfungistatic / fungicidal molecules.263. Comparative analysis of noncoding sequences in the Gibberella fujikuroi species complex. Christian Sieber 1 , Ulrich Güldener 1 , MartinMünsterkötter 1 , Karsten Suhre 1,2 . 1) Helmholtz-Zentrum München, Neuherberg, Bayern, GermanyHelmholtz Zentrum München, German Research Centerfor Environmental Health, Institute of Bioinformatics and Systems Biology, 85764 Neuherberg, Germany; 2) Department of Physiology and Biophysics,Weill Cornell Medical College, Education City, Qatar.Initially genome analysis methods focused on the coding part and its resulting proteins, therefore the role of noncoding DNA features was widelyunregarded for a long time. Due to the luxuriance of new sequencing technologies a plurality of genome sequences are now available and many differentrepeat families could been identified already, which exhibit a diversity of functions such as mRNA stabilization or the control of translation (Khemici 2004,Espeli 2001). Interspersed repeats account for a considerable amount of noncoding sequence in fungal genomes. The proportion of repetitive elementsand the compositions of repeat families differ from species to species whereas little is known about their origin and impact on the genomic functionality.The availability of new Fusarium genome sequences facilitate an extensive comparative approach across the Gibberella fujikuroi species complex. Besidesknown transposable elements and satellite repeats, a diversity of previously unknown interspersed repeat families are prominent in F.fujikuroi and closelyrelated species. While some of them are distributed through the whole complex, others can exclusively be found in only one genome. Interestingly thepredicted secondary structures of the elements exhibit a stable fold in terms of free energy and complementary base pairing. Moreover gene-chip andRNA-seq experiments reveal that some elements are part of the transcriptome and still seem to propagate further in the genome. Main questions are:What influence do interspersed repeats have on genome structure and the speciation process of fungi? How can repeats contribute to host-pathogen27th Fungal Genetics Conference | 185