Résumé
Over the past decade, considerable advances have been made in the understanding of the role of fungal effectors, and especially small secreted proteins (SSPs), in the infectious process. NGS technologies offer powerful tools to study, at the genomic scale, how deep are SSPs involved in the adaptation of fungal populations to different host plants. We addressed this question in the plant pathogenic fungus Magnaporthe oryzae, the agent of blast on rice and other Poaceae. This species encompasses isolated genetic lineages specifically attacking different hosts. In the GEMO project, we sequenced eight strains of M. oryzae representing different genetic groups pathogenic of different species of Poacees (5 strains attacking rice Oryza sativa, 1 attacking wheat Triticum sp., 1 attacking foxtail millet Setaria sp., 1 attacking finger millet Eleusine sp.), and one strain of the sister species M. grisea (attacking fonio millet Digitaria sp). The nine genomes have been sequenced using NGS technologies (454 and Solexa/Illumina) and assembled by the Genoscope (Evry, France). We included the public reference strain of M. oryzae 70-15 in our analyses. Gene annotation and orthology predictions have been carried out. We also annotated transposable elements and assessed the amount of horizontal transfers. Here we present the characterization of the repertoires of SSPs in the nine genomes, established using classical predictors of peptide signals (SignalP), transmembrane domains (TMHMM), GPI anchors (PrediGPI) and subcellular location assignment (TargetP). These lists were then curated using two complementary approaches: systematic tBlastn searches of the SSP predicted in each genome against the nine genomic databases of the project (including its own), and gene mining through the RNAseq analysis of the in planta transcriptome of one of the strain. We will compare these lists with orthology predictions to analyze the core-secretome and the dynamics of gains/losses/duplications of SSPs in the different lineages. We will also address the question of co-localization of SSPs with transposable elements. Finally we will search for signatures of adaptive evolution in SSPs.