Genetic and pathogenic diversity of Pseudomonas syringae strains isolated from cucurbits

Abstract

This work was done to determine the diversity of pathogenic Pseudomonas syringae pv. lachrymans and pv. syringae strains, isolated from cucurbit plants. Pathogenicity tests performed in this work on cucumber indicated that the 22 tested strains differed dramatically in virulence level. Genetic characterization using MLST loci, as well as ITS1, ERIC and REP fingerprinting, allowed the grouping of strains into four phylogenetic groups. After amplicon sequencing and BLAST alignment the collected strains comply with P. syringae pathovars: lachrymans and syringae and with saprophytic P. fluorescens. The strains of Pseudomonas syringae pv. lachrymans may be categorized into at least two types differing in both disease symptoms and molecular characteristics. We confirmed that MLST-loci-based grouping of strains corresponds well to grouping based on pathogenicity tests.

Genome analysis of Pseudomonas syringae pv. lachrymans strain 814/98 indicates diversity within the pathovar

“…The symptoms caused by strain 814/98 on cucumber leaves never failed to develop in every single test over the course of many years of testing. This strain did not produce fluorescent pigment on King's medium B but displayed the typical phenotypic and biochemical characteristics of P. syringae in LOPAT tests (Olczak-Woltman et al 2007;Olczak-Woltman et al 2008;Słomnicka et al 2015).…”

“…We previously attempted to describe the collected cucumber strains (OlczakWoltman et al 2007;Słomnicka et al 2015); however, a more precise methodology and new data are beginning to challenge old conclusions. Baltrus (2016) proposed a sequence-based classification system that is unambiguous and would enable microbial classification without abandoning previous taxonomic systems.…”

“…In order to identify plasmids in strain 814/98, we simultaneously incorporated various methodologies, e.g. a search for similarity to known plasmids, bioinformatic analysis of structural plasmid genes, genome coverage with reads and laboratory plasmid isolation (Słomnicka et al 2015). The bioinformatic analysis showed that strain 814/98 contains at least three plasmids.…”

“…The bacterial strain Both virulence and genetic diversity of the strains collected at the Department of Plant Genetics, Breeding and Biotechnology of WULS were described previously (Olczak-Woltman et al 2007;Słomnicka et al 2015). Based on those studies, pathovar lachrymans strain 814/98, recognized as the most virulent strain to cucumber, was chosen for genome sequencing.…”

“…BLAST results for gene sequences present on the plasmids and their descriptions are presented in Table S7. Plasmid identification on Eckhardt gels was performed previously (Słomnicka et al 2015).…”