Dressing like a pathogen: Comparative analysis of different Pseudomonas genomospecies wearing different features to infect Corylus avellana

Abstract

During the last decade, the European hazelnut (Corylus avellana) has been threatened by several bacterial and fungal infections. In particular, at least four different Pseudomonas species have developed the capability to converge into the same host. However, one of these species, Pseudomonas avellanae, may infect other hosts as well. Here, we newly provide the complete genome sequence of two Pseudomonas avellanae strains obtained by a combination of long Oxford Nanopore Technologies reads (ONT) and short Illumina reads. These have been included in a comparative analysis with all the genomes of Pseudomonas strains known to infect Corylus avellana available on the NCBI database, and the genomes of Pseudomonas avellanae strains infecting other host plants, like Prunus, Actinidia and from the river epilithon. The Pseudomonas strains clustered according to their taxonomy, host and geographic origins. The identification of specific traits related to each population cluster could give us insights regarding the host–pathogen interaction and the host range specificity. Indeed, the Pseudomonas avellanae strains infecting hazelnut have a peculiar set of three type III secretion effectors, while the Pseudomonas avellanae infecting Prunus and Actinidia are carrying the genomic WHOP island, necessary for woody-host infection. The syringae cluster, instead, contains more phytotoxins, the ice nucleation cluster, but less effectors. Thus, here, we confirmed that the convergence into the same host was possible due to different unrelated mechanisms of infection.