The N-acetyltransferase gene-implicated iron acquisition contributes to host specificity of Pseudomonas cichorii strain SPC9018 and its virulence

• Published in: Physiological and molecular plant pathology 2015-10, Vol.92, p.14-21
• Main Authors: Wali, Ullah Md, Mori, Yuka, Maenaka, Risa, Kai, Kenji, Tanaka, Masayuki, Ohnishi, Kouhei, Kiba, Akinori, Hikichi, Yasufumi
• Format: Article
• Language: English
• Subjects: Host specificity; Iron acquisition; N-acetyltransferase gene; Pseudomonas cichorii; Virulence
• ISSN: 0885-5765; 1096-1178
• DOI: 10.1016/j.pmpp.2015.08.008

A pathogenicity island within the genome of a multi-host plant bacterium, Pseudomonas cichorii strain SPC9018, comprises the hrp genes encoding a type III secretion system and the pat gene encoding an N-acetyltransferase proposed to play a role in virulence. However, the function of the N-acetyltransferase remains poorly characterized. Interestingly, limiting the iron condition using a phytosiderophore, mugineic acid, resulted in reduced virulence of strain SPC9018 on respective host plants, including eggplant, similar to the reduced virulence observed with a pat gene-deletion mutant. Spectroscopic analyses showed that the pat deletion reduced the concentration of pyoverdine, which is the main siderophore produced by strain SPC9018, leading to a reduction in pyoverdine-mediated iron acquisition. Furthermore, the pat gene deletion mutant showed enhanced expression of the fecA, pvdL, and pvdR genes, whose expression is induced under deficient siderophore-mediated iron uptake. The pat-deletion mutant showed a hyper-swarming phenotype, and the addition of iron decreased this swarming motility. The pat deletion also reduced the adhesion ability of the bacteria, similar to the effect of iron-limited conditions. Furthermore, deletion of the pat gene enhanced expression of the hrp genes. These findings suggested that the pat gene encoding the N-acetyltransferase may be implicated in iron acquisition, contributing to host specificity of P. cichorii strain SPC9018 and its virulence. •The iron-limiting condition resulted in reduced virulence of Pseudomonas cichorii.•Deletion of the pat encoding an N-acetyltransferase also reduced its virulence.•The pat was involved in extracellular concentration of a siderophore, pyoverdine.•Reduced extracellular concentration of pyoverdine led to the iron-limiting condition.•The pat-involved iron acquisition contributed to its host specificity and virulence.