Members of the pPT23A plasmid family of Pseudomonas syringae play an important role in the interaction of this bacterial pathogen with host plants. Complete sequence analysis of several pPT23A family plasmids (PFPs) has provided a glimpse of the gene content and virulence function of these plasmids. We constructed a macroarray containing 161 genes to estimate and compare the gene contents of 23...

In gram-negative bacteria, transporters belonging to the RND family are the transporters most relevant for resistance to antimicrobial compounds. In Pseudomonas aeruginosa, a clinically important pathogen, the RND-type pump MexAB-OprM has been recognized as one of the major multidrug efflux systems. Here, homologues of MexAB-OprM in the plant pathogens Pseudomonas syringae pv. phaseolicola 1448...

Pseudomonas syringae strains deliver variable numbers of type III effector proteins into plant cells during infection. These proteins are required for virulence, because strains incapable of delivering them are nonpathogenic. We implemented a whole-genome, high-throughput screen for identifying P. syringae type III effector genes. The screen relied on FACS and an arabinose-inducible hrpL sigma ...

The bean (Phaseolus spp.) plant pathogen Pseudomonas syringae pv. phaseolicola is characterized by the ability to produce phaseolotoxin (Tox(+)). We recently reported that the majority of the Spanish P. syringae pv. phaseolicola population is unable to synthesize this toxin (Tox(-)). These Tox(-) isolates appear to lack the entire DNA region for the biosynthesis of phaseolotoxin (argK-tox gene ...

Phytopathogenic strains of Pseudomonas syringae are exposed to plant-produced, detrimental levels of hydrogen peroxide during invasion and colonization of host plant tissue. When P. syringae strains were investigated for their capacity to resist H2O2, they were found to contain 10- to 100-fold-higher levels of total catalase activity than selected strains belonging to nonpathogenic related taxa...

The extent to which diel changes in the physical environment affect changes in population size and ice nucleation activity of Pseudomonas syringae on snap bean leaflets was determined under field conditions. To estimate bacterial population size and ice nucleation activity, bean leaflets were harvested at 2-h intervals during each of three 26-h periods. A tube nucleation test was used to assay ...

Pseudomonas syringae pv. tomato, the causal agent of bacterial speck of tomato, and the plant growth-promoting bacterium Azospirillum brasilense were inoculated onto tomato plants, either alone, as a mixed culture, or consecutively. The population dynamics in the rhizosphere and foliage, the development of bacterial speck disease, and their effects on plant growth were monitored. When inoculate...

The structure elucidation of the cyclic (lactonic) forms of the pyoverdins with a succinamide side chain originally produced by the closely related species Pseudomonas syringae and P. cichorii is reported. Mass spectrometry and nuclear magnetic resonance analyses as well as the determination of the configuration of the amino acids after degradation indicate that these two pyoverdins differ only...

To assess the role of MORC1 in epigenetics in relation to plant immunity, genome-wide chromatin accessibility was compared between mock- or Pseudomonas syringae pv. tomato-inoculated wild type (WT) Arabidopsis, the morc1/2 double mutant, or both. Most changes in chromatin accessibility, scored by DNase I hypersensitive sites (DHSs), were located in the promoters of genes and transposable elemen...

Phylogenetic relationships among 77 bacterial strains belonging to Pseudomonas syringae and Pseudomonas viridiflava species were assessed by analysis of the PCR-restriction fragment length polymorphism (RFLP) patterns of three DNA fragments corresponding to rrs and rrl genes and the internal transcribed spacer, ITS1. No difference among all strains in rrs and rrl genes was observed with 14 rest...