Program Book - 27th Fungal Genetics Conference

FULL POSTER SESSION ABSTRACTSOne of Znf2 downstream targets is extracellular protein Cfl1. Cfl1 is a cell-wall bound adhesin and a signaling molecule when it is released. This matrixprotein Cfl1 plays a similar but less prominent role than Znf2 in orchestrating morphogenesis and virulence in C. neoformans. Through transcriptomeanalyses and screening Znf2 downstream targets by overexpression, we identified an additional player in the control of morphogenesis and biofilmformation. This factor is an intracellular RNA-binding protein Pum1. As expected, Pum1 affects filamentation in a Znf2 dependent manner. However, theeffect of Pum1 on morphogenesis is independent of Cfl1. The pum1D cfl1D double mutant shows a more severe defect in filamentation than either of thesingle mutant, indicating that Pum1 and Cfl1 act in two parallel pathways. Two of Pum1’s targets, Fad1 and Fad2, form a Cryptococcus-specific adhesinfamily. Like Cfl1, these two extracellular adhesins show regulatory roles in conducting morphogenesis and virulence in C. neoformans and thus may beinvolved in extracellular signaling transduction. Our results indicate that complex regulatory cascades composed of extracellular and intracellular circuitsmay be responsible for mediating morphological transition in response to the cues in the environments and the host.511. Evidence for alkaloid diversity and independent hybridization events of Elymus endophytes. Nikki D. Charlton 1 , Juan Pan 2 , Daniel G. Panaccione 3 ,Christopher L. Schardl 2 , Carolyn A. Young 1 . 1) Forage Improvement Division, The Samuel Roberts Noble Foundation, Ardmore, OK; 2) Department of PlantPathology, University of Kentucky, Lexington, KY; 3) Division of Plant & Soil Sciences, West Virginia University, Morgantown, WV.The epichloae form mutualistic symbioses with cool-season grasses and have been shown to impart biotic and abiotic fitness benefits to their hosts.Endophyte-infected plants often have greater resistance to biotic stresses such as mammalian and insect herbivory due to the presence of fungalsynthesized alkaloids. Four classes of bioprotective alkaloids have been described, which include ergot alkaloids, indole-diterpenes, a pyrrolopyrazine(peramine), and saturated aminopyrrolizidines (lolines). Elymus species, such as Elymus canadensis and E. virginicus, are cool-season bunchgrasses nativeto much of North America and are known to harbor Epichloë endophytes. Three species are able to associate with Elymus: the non-hybrids Epichloëamarillans and Epichloë elymi and Epichloë canadensis, a hybrid with E. elymi and E. amarillans ancestral progenitors. The distribution and alkaloidgenotypic variation of these fungi was examined to determine endophyte variation that may provide ecological benefits to the host. Endophyte infectionfrequencies from natural populations and germplasm resources ranged from uninfected to highly infected. Analyses of microsatellite loci and mating typegenes characterized the prevalence and distribution of hybrid and non-hybrid endophytes among and between Elymus populations. Overall, non-hybridswere more prevalent than hybrids in the northern region of the U.S., whereas hybrids were more ubiquitous in the southern region. Genotypic analysisbased on presence and absence of key alkaloid biosynthesis genes provided information about the potential alkaloid diversity within these populations.Thirteen unique alkaloid genotypes were identified that showed variation within the EAS (ergot alkaloid), LOL (loline) and PER (peramine) loci thatindicates some genotypes are likely to accumulate pathway intermediates. Evaluation of the mating-type idiomorphs from the hybrid E. canadensisindicates this species has resulted more than once through independent hybridization events thus explaining variation found among the alkaloid genes.Chemical analyses of representative endophyte-infected plants are being conducted to correlate alkaloid predictions with actual alkaloid production.Chemotype diversity will be evaluated to determine how this translates into differences in fitness and persistence of the host.512. The functional characterization of candidate genes involved in host specialization of Zymoseptoria grass pathogens. Stephan Poppe, Petra Happel,Eva Stukenbrock. Fungal Biodiversity, Max Planck Institute Marburg, Marburg, Germany.The ascomycete fungus Zymoseptoria tritici (synonym: Mycosphaerella graminicola) emerged as a new pathogen of cultivated wheat during cropdomestication about 11.000 years ago. To understand the molecular basis of host specialization in this pathogen we have sequenced complete genomes ofZ. tritici and closely related species infecting wild grasses. Evolutionary genomic analyses allowed us to identify 17 genes that show strong evidence ofpositive selection between Z. tritici and the closely related sister species Zymoseptoria pseudotritici. We hypothesize these evolved in a co-evolutionaryarms race with different hosts. None of the genes encode proteins with known function. In this study we focus on three candidate genes Mgr80707, Mgr89160 & Mgr 103264 and investigate their role in Z. tritici and its two closest relatives Z. pseudotritici and Z. ardabiliae during host infection. QuantitativeReal time PCR experiments from the three fungal species infecting four different grass species show that the three genes are strongly up-regulated inplanta and that candidate gene expression differs over a time course of 28 days supporting a role in host pathogen interaction. In addition, we show thatthree different host species (wheat, Elymus repens and Lolium multiflorum) differentially induce gene expression in the fungi. Confocal Laser ScanningMicroscopy conducted at different time points reveals clear differences between Zymoseptoria species during infection and within host development inwheat and Brachypodium distachyon. Deletion strains for each candidate gene have been created by Agrobacterium tumefaciens mediatedtransformation. The single deletion of two candidate genes Mgr80707 & Mgr103264 led to a reduced virulence of Z. tritici on wheat. The deletion of thethird gene Mgr89160 led to a hyper-virulence phenotype suggesting an avirulence function of the gene product. Our study confirms that genes involved inhost specialization can be identified based on footprints of natural selection.513. Diversity and Phylogeny of genus Suillus (Suillaceae, Boletales) from Pakistan (Asia). Samina Sarwar, Abdul Nasir Khalid. Botany, University of thePunjab, Lahore, Punjab, Pakistan.Coniferous forests of Pakistan are rich in mycodiversity. However, only a few scientific researches have been conducted in these forests. This paper aimsto document diversity of Suillus in these forests. During a survey conducted during 2008-2010, a total of thirty two (32) basidiomata were collected. Mostof them were found associated with Pinus wallichiana and Abies pindrow. Only a few were found with Cedrus deodara, Populus ciliata and Quercus spp.These basidiomata were characterized morphologically as well as by molecular analysis by amplifying rDNA. Fungal specific primers ITS3 & ITS6R and ITS2& ITS8F were used to amplify the ITS1 and ITS2 along with partially 5.8S gene. Out of these, twelve (13) different Suillus species were found. Among themtwo (2) species seem undescribed and three (3) as new records for Pakistan. Their Phylogenetic relationships have also been discussed.514. Saprolegnia species can switch hosts to cause infection: a new insight into host pathogen interaction. Mohammad N. Sarowar 1* , A. Herbert van denBerg 1 , Debbie McLaggan 1 , Mark Young 2 , Pieter van West 1 . 1) Institute of Medical Sciences, Foresterhill, Aberdeen, AB25 2ZD, United Kingdom; 2)Department of Zoology, University of Aberdeen, Aberdeen, AB24 2TZ, United Kingdom.Saprolegnia species are destructive oomycete pathogens of many aquatic organisms and are found in all parts of the world. Phylogenetic analysis hasshown that Saprolegnia strains isolated from different aquatic organisms have a close relationship to fish pathogenic Saprolegnia species. We have nowdemonstrated, for the first time, that Saprolegnia spp. can actually switch hosts. Saprolegnia australis, Saprolegnia hypogyna and 2 strains of Saprolegniadiclina were isolated from insects. We also collected other oomycete species, including S. australis, S. ferax, Pythium pachycaule and Pythium sp., in waterof a medium to fast running river. The ITS region of all these isolates was sequenced. Four isolates collected from the aquatic insects together with isolatesof S. parasitica (collected from salmon), S. diclina (collected from trout eggs) and S. ferax (collected from an amphibian) were tested for pathogenicity onnymphs of a stonefly (Perla bipunctata), Atlantic salmon eggs and frog (Xenopus leavis) embryos. Most of the isolates were highly pathogenic on all testedaquatic animals. These results suggest that Saprolegnia spp. are capable of switching host, which may be related to seasonal variation of host availability in27th Fungal Genetics Conference | 247