Genetic, biochemical and pathogenic diversity of Pseudomonas syringae pv. pisi strains

Abstract

Pseudomonas syringae pv. pisi is a seedborne pathogen distributed worldwide that causes pea bacterial blight. Previous characterization of this pathogen has been carried out with relatively small and ⁄ or geographically limited samples. Here, a collection of 91 strains are examined that include strains from recent outbreaks in Spain (53 strains) and from 14 other countries, and that represent all races and the new race 8, including the type race strains. This collection was characterized on the basis of 55 nutritional tests, genetic analysis (rep-PCR, amplification of AN3 and AN7 specific markers, and multilocus sequence typing (MLST)) and pathogenicity on the differential pea cultivars to identify races. Principal component analysis and distance dendrograms confirm the existence of two genetic lineages within this pathovar, which are clearly discriminated by the AN3 ⁄ AN7 markers, rep-PCR and MLST. Strains from races 1 and 7 amplified the AN3 marker; those from races 2, 6 and 8 amplified AN7, while strains of races 3, 4 and 5 amplified either AN3 or AN7. Nevertheless, strains were not grouped by race type by any of the genetic or biochemical tests. Likewise, there was no significant association between metabolic and ⁄ or genetic profiling and the geographical origin of the strains. The Spanish collection diversity reflects the variability found in the worldwide collection, suggesting multiple introductions of the bacteria into Spain by contaminated seed lots.

Host Range Determinants of Pseudomonas savastanoi Pathovars of Woody Hosts Revealed by Comparative Genomics and Cross-Pathogenicity Tests

“…First, the Psv genomes are distributed in two separated clades, clustering with either Psr or Psn genomes ( Figure 2 ). Although intriguing, the occurrence of different genetic lineages for a given pathovar is not new nor surprising ( Gironde and Manceau, 2012 ; Martín-Sanz et al., 2012 ; Martín-Sanz et al., 2013 ; Hulin et al., 2018 ), because pathovars are defined for causing distinctive disease syndromes and not necessarily for their genetic relatedness ( Young et al., 1992 ). Nevertheless, olive is a frequent host for the four pathovars and, since strains of P. savastanoi can cause knots in diverse species ( Caballo-Ponce et al., 2017a ), it is also possible that the two Psv genetic lineages show differing host ranges.…”

Breeding for Biotic Stress Resistance in Pea

“…pisi have been reported to affect peas [107]. Race-specific monogenic resistances have been identified and mapped [108][109][110][111]. Additional QTLs have also been reported [112].…”

The Mangotoxin Biosynthetic Operon ( mbo ) Is Specifically Distributed within Pseudomonas syringae Genomospecies 1 and Was Acquired Only Once during Evolution

“…syringae pv. pisi lineages (54), the possibility that the previously analyzed strains belong to a phylogenetic lineage that does not produce toxins.…”