Résumé
Magnaporthe oryzae is a fungal species complex gathering pathogens of different Poaceaes that causes the main fungal disease of rice and severe epidemics on wheat in South America. This project aims at characterizing genomic determinants and evolutionary events involved in the adaptation of fungi to different host plants. Eight strains from M. oryzae species complex pathogenic on either rice, wheat, Setaria or Eleusine and one strain of the related species M. grisea pathogenic on Digitaria, have been sequenced using NGS. De novo annotation was carried out with Eugene for gene and with REPET for transposons. Most frequent families are LTR retro-transposons, but some DNA transposons were found. Repeats cover about 10-12% of these genomes. Variable genome sizes (36- 42 Mb) and gene contents (12 300-20 500 genes) were estimated for these genomes, even though 4 genomes were more fragmented (poor scaffolding, short and truncated CDS). OrthoMCL analysis including M. oryzae 70-15 reference genome, identified 20 443 clusters, including 8 154 single copy shared by-all families (core genome) and variable number of species-specific gene families (305-1550). Gene families expected to be involved in pathogenicity including genes encoding enzymes involved in the biosynthesis of secondary metabolites, enzymes involved in plant cell wall degradation and small secreted peptides are currently analyzed. 12- 14% of the predicted CDS encode putative secreted proteins with a median length of 260 aa. A dedicated database was developed to facilitate evolutionary analyses and integration of RNAseq data from in planta infection kinetics. Additional comparative analyses will be presented. (Texte intégral)