Pseudomonas syringae pv. syringae Genome sequencing and assembly. Pseudomonas syringae pv. syringae

Pseudomonas syringae pv. syringae has recently been identified as the main causal agent of bacterial canker in the Western Cape Province of South Africa. In addition to pathovar syringae, several other pathovars including morsprunorum, cerasicola, avii and recently Pseudomonas cerasi have been identified as stone fruit pathogens. Even though more genomes of stone fruit pathogens are becoming available, the genetic basis of the epidemiology of these pathogens is still poorly understood. In this study, two genomes of P. syringae pv. syringae isolated from diseased cherry trees in South Africa were sequenced using the Illumina MiSeq platform and compared to P. syringae genomes from other stone fruit trees. The genomes were compared in terms of genomic features, genes associated with an epiphytic life style, virulence genes and genes specifically associated with the woody niche. In addition, genomic islands (GI’s) and plasmids were identified by SeqWord genomic island and SPAdes genome assembler respectively and their role in conferring strains with fitness on woody hosts was investigated. This study shows that P. syringae pathogenic on stone fruit have a genetic make-up suitable for an extensive epiphytic phase and that fitness genes appear to be linked to Phylogroup (PG). It also shows that HGT and plasmids plays a minor role in host specific fitness of these pathogens.