Program Book - 27th Fungal Genetics Conference

FULL POSTER SESSION ABSTRACTScells via type three section systems, a syringe like apparatus that directly penetrates the host cell plasma membrane. Currently, there is no evidence forsuch translocation machinery being present or utilized by fungal and oomycete symbionts to deliver effector proteins. Several bacterial and fungal toxinsutilize external glycosphingolipids to mediate translocation into cells. Upon internalization a subset of these toxins escape endosomal compartments viaretrograde transport to the Golgi-endoplasmic reticulum trans network, while others are capable of flipping across the endosomal membrane. The genusPhytophthora contains a number of highly destructive plant pathogens. Comparative genomics and the sequence availability of known intracellulareffectors resulted in the discovery of a highly conserved N-terminal motif RXLR-dEER that defines an expansive super family of secreted proteins. TheRXLR-dEER motif of PsAvr1b, PsAvr1k, and PsAvh5 has been shown to facilitate effector entry into a plant and animal cells in the absence of any pathogenencoded machinery. Entry is believed to be mediated by binding cell surface phospholipid, phosphatidylinositiol-3-phosphate. Using isothermal titrationcalorimetry we have characterized the phospholipid binding properties of the RXLR effectors PsAvr1b, PiAvr3a, and several RXLR-like effectors to monoand poly phosphatidylinositol-phosphates in a variety of experimental conditions. As controls we have characterized the phospholipid binding propertiesof 2xFYVE and Vam7pX, two known PI3P binding domains.519. Investigating virulence effectors in the poplar-poplar rust pathosystem. Sebastien Duplessis 1 , Benjamin Petre 1 , Hugo Germain 2,3 , Arnaud Hecker 1 ,Stéphane Hacquard 1 , David L Joly 4 , Armand Séguin 2 , Nicolas Rouhier 1 . 1) UMR1136 IAM, INRA, Champenoux, France; 2) Natural Resources Canada,Canadian Forest Service, Laurentian Forestry Centre, Quebec, QC, Canada; 3) Université du Québec à Trois-Rivières, Trois-Rivières, QC, Canada; 4)Agriculture and Agri-Food Canada, Pacific Agri-Food Research Centre, Summerland, BC, Canada.Foliar rust caused by Melampsora larici-populina is a major disease affecting poplar plantations throughout the world. The obligate biotrophic status ofthe fungus and the perennial status of the host plant, make molecular investigation of this interaction a real challenge. However, availability of bothPopulus trichocarpa and Melampsora larici- populina sequenced genomes has allowed for setting an emerging model pathosystem to decipher themolecular bases of disease resistance in trees and of biotrophic growth in rust fungi. Comprehensive analyses of rust transcripts encoding small secretedproteins expressed in planta identified putative virulence factors and we focused our attention on a few candidates that show evidence of purifyingselection between paralogs. In particular, two gene families encode modular SSP with a conserved N-terminal part and a C-terminal part evolving underpositive selection except highly-conserved cysteine residues. Gene family 5464 contains 13 members, homologs of Melampsora lini AvrP4 avirulencefactors whereas H1 family gather 31 genes specific to M. larici-populina. Some of these genes present a transient peak of expression during the biotrophicgrowth of the fungus in poplar leaves, and the corresponding proteins are able to enhance bacterial growth when delivered in Arabidopsis thaliana fromPseudomonas syringae pv tomato DC3000. Currently, we combine a range of approaches including biochemical and structural characterization ofrecombinant proteins, yeast two-hybrid and pull-down assays to characterize these candidate effectors.520. Functional analysis of Aphanomyces euteiches effectors, a legume root pathogen. D. Ramirez-Garces, L. Camborde, H. San Clemente, A. Cerutti, B.Dumas, E. Gaulin. LRSV UMR5546 CNRS/UPS, Castanet-Tolosan, France.Aphanomyces euteiches is an oomycete infecting roots of various legumes species such as pea, alfalfa and the model legume Medicago truncatula. Thegenus Aphanomyces, which belongs to the group of Saprolegniales, is phylogenically distant from the well known Phytophthora genus and comprises bothanimal pathogen and plant pathogen species. The first genome draft of Aphanomyces euteiches (ATCC201684, 57 Mb) will be soon released and genomesequencing of zoo- and phytopathogen species are under progress. A. euteiches genome miming revealed the expansion of CRNs (Crinkling and Necrosis)genes, initially identified in Phytophthora infestans. These modular proteins contain a conserved N-terminal characterized by the presence of a LFLAKamino acid motif implicated in the protein translocation from the pathogen to the host cell, whereas the modular C-terminal effector domain is highlydiverse. The proposed role of the CRNs effectors is to suppress plant defense or to modulate other host cell processes that increase susceptibility andenhance pathogen virulence. In A. euteiches, the active translocation LYLAK motif was detected, and conserved, as well as original effector subdomains,were identified. Functional studies conducted on two types of A. euteiches CRNS, AeCRN5 and AeCRN13, showed that both proteins are highly inducedduring infection of M. truncatula roots. In planta expression of both proteins revealed host nucleus localization and cell-death induction or alteration ofroots architecture when expressed in plant cells. Such observations suggest that A. euteiches CRNs are virulence proteins exerting their function throughthe interaction with nuclear compounds. Latest results regarding the putative function of AeCRNs will be presented.521. Participation of effector proteins from Trichoderma spp. in interaction with Arabidopsis thaliana. P. Guzman-Guzman 1 , M.I. Aleman-Duarte 2,3 , L.J.Delaye-Arredondo 3 , A. Herrera-Estrella 2 , V. Olmedo-Monfil 1 . 1) Biology Dept,University of Guanajuato, Guanajuato, Guanajuato, Mexico; 2) CINVESTAV,Langebio Unit, Irapuato Unit, Irapuato, Guanajuato, Mexico; 3) CINVESTAV, Irapuato Unit, Irapuato, Guanajuato, Mexico.When a plant-pathogen interaction is established, plant activates its immune response system, recognizing pathogen’s virulence factors. In plantresponse are involved several phytohormones. Studies on plant pathogenic processes triggered by different organisms have shown the involvement ofsome pathogen proteins that are capable of altering the function and structure of the host cell, facilitating their entry and affecting overall host physiology,these proteins are known as "effectors". The effectors activity inside the host takes place through conserved mechanisms of molecular interaction, such aseffectors that have the RXLR translocation motif, which is highly conserved among different pathogens, directing its entry into the host cells. In plantpathogeninteractions, effectors are recognized, activating the plant response system. However, some of these molecules have been involved in theestablishment of plant interactions with non-pathogenic organisms; little is known about the mechanisms controlling the establishment of this beneficialinteraction. Fungi of the genus Trichoderma establish beneficial interactions with plants, promoting their growth and defense systems. To betterunderstand this biological process, it is important to identify effector-like molecules in species like Trichoderma, and to establish their role in promotingplant development and defense systems activation. To achieve this goal, we will test the interaction of Trichoderma species with Arabidopsis thaliana,focusing on the selection and identification of effector-like molecules that are expressed during this interaction process. Additionally, we will generate nullTrichoderma mutants on these effector-like candidates to evaluate their participation in the plant-fungus interaction. Until now, we have establishedinteraction conditions, confirming the effect of the fungus presence over plant biomass production and root growth, showing interesting morphologicchanges in the root system, such as a significant increase in lateral root formation. Based on conserved characteristics and bioinformatics tools, weselected 16 encoding sequences for effector-like molecules among T. virens and T. atroviride genomes, and we confirmed the differential expression of 7of them in interaction with A. thaliana, by RT-PCR analysis.522. The role of LysM effectors in fungal fitness. Anja Kombrink 1 , Jason Rudd 2 , Dirk-Jan Valkenburg 1 , Bart Thomma 1 . 1) Phytopathology, WageningenUniversity, Wageningen, Netherlands; 2) Department of Plant Pathology and Microbiology, Rothamsted Research, Harpenden, Hertfordshire, UnitedKingdom.LysM effector genes are found in the genomes of a wide range of fungal species. The encoded LysM effectors are secreted proteins that contain a varying27th Fungal Genetics Conference | 249