Genetic and functional diversity of PsyI/PsyR quorum-sensing system in the Pseudomonas syringae complex

作者：Tomohiro Morohoshi, Akinori Oshima, Xiaonan Xie, Nobutaka Someya · 发表于：FEMS Microbiology Ecology · 年份：2020 · DOI：10.1093/femsec/fiaa254 · 被引用次数：7 · 研究领域：Bacterial biofilms and quorum sensing、Plant Pathogenic Bacteria Studies、Plant-Microbe Interactions and Immunity

Strains belonging to the Pseudomonas syringae complex often possess quorum-sensing systems that comprise N-acyl-l-homoserine lactone (AHL) synthases (PsyI) and AHL receptors (PsyR). Here, we investigated the diversity of PsyI/PsyR quorum-sensing systems in 630 strains of the P. syringae complex. AHL production was observed in most strains of Pseudomonas amygdali and Pseudomonas meliae, and a few strains of Pseudomonas coronafaciens and P. syringae. The DNA sequences of psyIR and their upstream and downstream regions were categorized into eight types. P. amygdali pv. myricae, Pseudomonas savastanoi, and P. syringae pv. solidagae, maculicola, broussonetiae, and tomato encoded psyI, but did not produce detectable amounts of AHL. In P. savastanoi, an amino acid substitution (R27S) in PsyI caused defective AHL production. The psyI gene of P. syringae pv. tomato was converted to pseudogenes by frameshift mutations. Escherichia coli harboring psyI genes from P. amygdali pv. myricae, P. syringae pv. solidagae and broussonetiae showed high levels of AHL production. Forced expression of functional psyR restored AHL production in P. amygdali pv. myricae and P. syringae pv. solidagae. In conclusion, our study indicates that the PsyI/PsyR quorum-sensing systems in P. syringae strains are genetically and functionally diverse, with diversity being linked to phylogenetic and pathovar classifications.