Complete Genome Sequence Resources for <i>Pseudomonas syringae</i> Strains 508 and TLP2

Some naturally occurring isolates of the ubiquitous phytopathogen Pseudomonas syringae have been reported to be nonpathogenic despite sharing common pathology-associated genetic features. Here, we present the complete genome of two putatively nonphytopathogenic Pseudomonas strains, P. syringae strain 508 and P. syringae TLP2, which are members of Phylogroup 2c within the P. syringae species complex. Comparison with the closely related reference strain P. syringae pv. syringae B728a reveals at least two major structural rearrangements that are likely involved in bacteria–bacteria or bacteria–host interactions. One key rearrangement is the relocation of the pathogenicity island encoding the atypical variant of the type III secretion system (T3SS) to a location more than 270 kbp downstream, decoupling the genomic island from many genes in both the canonical conserved and exchangeable effector loci. This change coincides with a reduction of effector genes within the T3SS pathogenicity island and, more generally, a reduction of effector genes in the genomes of both nonphytopathogenic strains. Identification of regions of genetic mobility and novel targets using complete positional data will aid in the study of the genetic associations with phenotypic variability in phytopathology in P. syringae strains. [Formula: see text] Copyright © 2025 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .