Résumé
For more than a century, Coffee Leaf Rust caused by the biotrophic fungus Hemileia vastatrix, has increasingly stood out as one of the major factors hampering Arabica coffee production. Since its first historical outburst in the 19th century in Sri Lanka, this disease has rapidly spread worldwide and currently occurs in nearly all the regions of the world where coffee is grown. Despite its widespread distribution and negative economic impact, little is known about its evolutionary origin and phylogenetic placement in the fungal tree of life. Attaining this knowledge, however, would provide fundamental insights on the evolutionary context in which H. vastatrix emerged, which in turn could have important implications to understand the evolution of pathogenicity in this pathogen and in other rusts as well. With this in mind, we are undertaking a genomescale approach that will allow H. vastatrix and other rust fungi to be placed in the fungal tree of life with unprecedented detail by using complete proteomes of five Pucciniomycotina species, approximately 250 000 publicly available EST sequences from several Pucciniomycotina species and H. vastatrix’s recently obtained transcriptome. A high quality matrix that includes orthologs, co-orthologs and recent paralogs is currently being prepared with a sophisticated orthology detection strategy. On a first approach, we have been able to indentify at least 1040 single-copy orthologs that will be used for the phylogenetic analyses. Providing robust and resolved phylogenetic relationships will lay the ground for the identification of genes or gene families that are exclusive to H. vastatrix as well as genes of rapid evolution and/or subject of positive selection, which would be prime targets for functional studies aiming at disease control and prevention. This information will ultimately contribute significantly to advance our knowledge on H. vastatrix’s pathogenicity.