Program Book - 27th Fungal Genetics Conference

FULL POSTER SESSION ABSTRACTSVan de Wouw 2 , Barbara J. Howlett 2 . 1) Marcroft Grains Pathology, Grains Innovation Park, Horsham, 3400, Vic., Australia; 2) School of Botany, theUniversity of Melbourne, 3010, Vic., Australia.Blackleg caused by Leptosphaeria maculans, is the most important disease of Brassica napus (canola) worldwide. Field populations of this sexuallyoutcrossing fungus rapidly adapt to selection pressure from extensive sowing of varieties with major gene resistance and can ‘overcome’ resistance. Thishigh evolutionary potential of the fungus is reflected in its genome structure. Effector genes are embedded in AT-rich, gene- poor regions withtransposable elements that have been degenerated by Repeat Induced Point (RIP) mutations. Thus effectors are easily gained, lost or inactivated. For thelast decade we have monitored virulence of blackleg populations and disease severity of varieties in field trials across Australia. In 2003 after two seasonsof extensive sowing, blackleg resistance of a set of varieties ‘broke down’ in the Eyre Peninsula, South Australia, causing 90% yield losses and withdrawal ofthese varieties from sale. By 2005, virulence of populations towards these varieties declined appreciably. Thus the blackleg-canola interaction behaves in a‘Boom and Bust’ manner. Analysis of isolates collected before and after the resistance breakdown showed that deletions, RIP mutations and amino acidsubstitutions accounted for rapid evolution of four linked effectors, including the avirulence gene complementary to the resistance gene that had beenovercome. After this resistance breakdown, Eyre Peninsula farmers sowed varieties with a different source of resistance. However in November 2011significant levels of disease in trial sites and commercial paddocks were observed, which led to a warning in February this year that these varieties shouldnot be sown. Growers heeded this advice and sowed varieties with different resistance sources. Our prediction of a resistance ‘breakdown’ was vindicated,as this variety had high disease levels in field trials on Eyre Peninsula, but not in other canola-growing regions. Commercial crops of other varieties on EyrePeninsula had only low levels of disease. By sowing other varieties, not only have farmers have been saved $20 million (based on conservative estimates ofarea sown, predicted yield loss and current canola prices), but seed companies have been able to sell the ‘at risk’ varieties in other canola-growing regions,where resistance breakdown was not predicted.654. Experimental demonstration of Crozier's paradox in fungi. Eric Bastiaans, Alfons J.M. Debets, Duur K. Aanen. Plant Science Group, WageningenUniversity, Wageningen, Netherlands.Kin selection can favour cooperation between individuals. This requires assortment between genetically related individuals and genetic kin recognition isthe predominant means to achieve this. However, Crozier realised that the diversity of kin-recognition alleles necessary for kin recognition, observed inmany social organisms, poses a paradox: common alleles will receive more cooperation than rare alleles, and therefore increase in frequency, thus erodinggenetic kin recognition diversity. We provide experimental evidence for Crozier’s theoretical prediction using somatic fusion between fungal individuals(mycelia) as a model for cooperation. Using fusion mutants and incompatible strains, we first show that fitness is strongly correlated with the degree offusion, which demonstrates that fusion between mycelia is mutually beneficial. We then experimentally demonstrate Crozier’s prediction that positivefrequency-dependent selection erodes kin-recognition diversity.655. A completely unknown lifecycle in mushrooms: cyclical inbreeding and haplo-diploidy. Duur K. Aanen 1 , Tim Möhlman 1 , Eric Bastiaans 1 , BartNieuwenhuis 1 , Bertha Koopmanschap 1 , Thomas W. Kuyper 2 . 1) Plant Science Group, Wageningen University, Wageningen, Netherlands; 2) Department ofSoil Quality, Wageningen University, Wageningen, The Netherlands.Mycena galericulata (Basidiomycota, Agaricales) occurs in two forms, a clampless with two-spored basidia and a clamped with four-spored basidia. It isgenerally accepted that the two-spored form is haploid asexual (apomictic), and the four-spored form sexual (dikaryotic and heterothallic). In order tostudy the interrelationship between both forms, we performed mating tests and phylogenetic and genetic analyses of a sample of both forms. Surprisingly,our results are inconsistent with any currently known life-cycle. While the four-spored form is heterothallic indeed, we show that the two-spored form isdiploid, and produces diploid spores via intra-tetrad selfing. However, the absence of genetic differentiation between both forms, and the high degree ofheterozygosity in the two-spored form, indicate that the two-spored form frequently arises from the four-spored. We hypothesise that the two-sporedform can again give rise to four-spored forms. Consistent with this, we discovered that a small percentage of fruiting bodies has both two-spored and foursporedbasidia.656. Diversity and evolution of ABC proteins in basidiomycetes. Andriy Kovalchuk 1 , Yong-Hwan Lee 1,2 , David Hibbet 3 , Fred O. Asiegbu 1 . 1) Department ofForest Sciences, University of Helsinki, Finland; 2) Department of Agricultural Biotechnology, Seoul National University, Seoul, Korea; 3) Department ofBiology, Clark University, Worcester MA 01610, USA.ABC proteins constitute one of the largest families of proteins. They are implicated in a wide variety of cellular processes ranging from ribosomebiogenesis to multidrug resistance. With the advance of fungal genomics, the number of known fungal ABC proteins increases rapidly, but the informationon their biological functions remains scarce. In this work, we extended our previous analysis of fungal ABC proteins to include recently genome sequencedspecies of basidiomycetes. We performed an identification and initial cataloguing of ABC proteins from 23 new species representing 10 orders from withinthe class of Ascomycotina. To identify gene loci encoding ABC proteins in the fungal genomes, multiple tblastn and blastp searches against selectedgenomes were performed at the website of the Fungal Genomics Program of the Department of Energy Joint Genome Institute (JGI). Sequences ofCoprinopsis cinerea ABC proteins representing all known subfamilies were used as queries. Phylogenetic analysis was performed with the programpackage MEGA5 using neighbor-joining, minimum evolution and maximum likelihood algorithms and bootstrapping with 500 replicates. ABC proteins ofeach species were separated into subfamilies by their comparison with S. cerevisiae, C. cinerea, C. neoformans and U. maydis proteins. Set of ABC proteinsidentified in basidiomycetes and ascomycetes were compared, and their common features and principal differences are discussed. Two groups of ABCproteins specific for basidiomycetes were identified. Results of the survey should contribute to a better understanding of evolution of ABC proteins in fungiand support further experimental work on their characterization.657. Co-evolution and life cycle specialization of plant cell wall degrading enzymes in a hemibiotrophic pathogen. Patrick C. Brunner 1 , Stefano F. F.Torriani 1 , Daniel Croll 1 , Eva H. Stukenbrock 2 , Bruce A. McDonald 1 . 1) Integrative Biology, ETH Zurich, Zurich, Switzerland; 2) Max Planck Institute forTerrestrial Microbiology, Marburg, Germany.Co-evolution of species has long been recognized as a driving force in generating and maintaining biodiversity. Co-evolution is an ubiquitousphenomenon investigated in prey and predator, plant and herbivore, or mutualistic interrelationships. However, signatures of co-evolution are likely to bestrongest in host-pathogen systems because of the strong selective pressures that each can exert directly on the other. While traditional studies mainlysought phenomenological evidence for co-evolution, more recent approaches look directly at the molecular/gene level. We hypothesized four mainscenarios for host-pathogen co-evolution and predicted the corresponding genetic signatures. We combined comparative genomics, transcriptomics andselection analyses to investigate genes that are likely affected by co-evolution to assign them to one of these scenarios. Zymoseptoria tritici is animportant fungal pathogen on wheat and has two closely related sister species Z. pseudotritici and Z. ardabiliae that infect wild grasses. This recently282