γ-Aminobutyric acid (GABA) is a widely distributed non-proteinogenic amino acid that accumulates in plants under biotic and abiotic stress conditions. Recent studies suggested that GABA also functions as an intracellular signaling molecule in plants and in signals mediating interactions between plants and phytopathogenic bacteria. However, the molecular mechanisms underlying GABA responses to bacterial pathogens remain unknown. In the present study, a GABA receptor, named McpG, was conserved in the highly motile plant-pathogenic bacteria Pseudomonas syringae pv. tabaci 6605 (Pta6605). We generated a deletion mutant of McpG to further investigate its involvement in GABA chemotaxis using quantitative capillary and qualitative plate assays. The wild-type strain of Pta6605 was attracted to GABA, while the ΔmcpG mutant abolished chemotaxis to 10 mM GABA. However, ΔmcpG retained chemotaxis to proteinogenic amino acids and succinic semialdehyde, a structural analog of GABA. Furthermore, ΔmcpG was unable to effectively induce disease on host tobacco plants in three plant inoculation assays: flood, dip, and infiltration inoculations. These results revealed that the GABA sensing of Pta6605 is important for the interaction of Pta6605 with its host tobacco plant.

中文翻译：

---

γ-氨基丁酸趋化性对丁香假单胞菌的毒力的要求。烟粉虱 6605


γ-氨基丁酸（GABA）是一种广泛分布的非蛋白氨基酸，在生物和非生物胁迫条件下在植物中积累。最近的研究表明，GABA 还充当植物中的细胞内信号分子以及介导植物与植物病原细菌之间相互作用的信号。然而，GABA 对细菌病原体反应的分子机制仍然未知。在本研究中，一种名为 McpG 的 GABA 受体在高活力植物病原菌丁香假单胞菌中保守。烟粉虱 6605 (Pta6605)。我们生成了 McpG 的缺失突变体，以使用定量毛细管和定性平板测定进一步研究其在 GABA 趋化性中的参与。 Pta6605 野生型菌株被 GABA 吸引，而 ΔmcpG 突变体则消除了对 10 mM GABA 的趋化性。然而，ΔmcpG 保留了对蛋白氨基酸和琥珀半醛（GABA 的结构类似物）的趋化性。此外，在三种植物接种试验中：淹没接种、浸渍接种和渗透接种，ΔmcpG 无法有效诱导宿主烟草植物发病。这些结果表明，Pta6605 的 GABA 感应对于 Pta6605 与其宿主烟草植物的相互作用非常重要。