ABSTRACT

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.

中文翻译：

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丁香假单胞菌复合体中PsyI / PsyR群体感应系统的遗传和功能多样性。

摘要

属于假单胞菌（Sseudomonas syringae）复合物的菌株通常具有群体感应系统，该系统包括N-酰基-1-高丝氨酸内酯（AHL）合酶（PsyI）和AHL受体（PsyR）。在这里，我们调查了丁香假单胞菌复合体的630个菌株中PsyI / PsyR群体感应系统的多样性。在大部分的杏仁假单胞菌和假单胞菌以及少数的假单胞菌和丁香假单胞菌中均观察到AHL的产生。psyIR的DNA序列及其上游和下游区域被分类为八种类型。杏仁核p。杨梅，假单胞菌和丁香假单胞菌pv。solidagae，maculicola，楮实，和番茄编码psyI，但没有产生AHL的检测量。在萨瓦氏疟原虫中，PsyI中的氨基酸取代（R27S）导致AHL产生缺陷。丁香假单胞菌pv的psyI基因。番茄通过移码突变转化为假基因。携带来自杏仁核pv的psyI基因的大肠杆菌。杨梅，丁香假单胞菌pv。solidagae和楮实表现出较高的水平AHL生产。功能性psyR的强制表达恢复了杏仁核pv中AHL的产生。杨梅和丁香假单胞菌。Solidagae。总之，我们的研究表明，丁香假单胞菌菌株中的PsyI / PsyR群体感应系统具有遗传和功能多样性，其多样性与系统发育和病原体分类相关。