Comparative Genomics of -Associated Members of the Species Complex Reveals Traits Supporting Co-evolution and Host Adaptation.

Members of the species complex cause symptoms that are ranging from leaf spots to cankers on a multitude of plant species, including some of the genus . To date, a total of two species of the species complex and six different pathovars have been associated with diseases on spp., which were shown to belong to different phylogenetic units (phylogroups, PG) based on sequence similarity of housekeeping genes or whole genomes, suggesting that virulence to spp. may be the result of convergent pathoadaptation. In this study, a comparative genomics approach was used to determine genes significantly associated with strains isolated from spp. across a phylogeny of 97 strains belonging to the species complex. Our study revealed the presence of a set of orthologous proteins which were significantly associated with strains isolated from spp. than in strains isolated from other hosts or from non-agricultural environments. Among them, the type III effector HopAY predicted to encode for a C58 cysteine protease was found to be highly associated with strains isolated from spp. and revealed patterns supporting co-evolution and host adaptation.