破坏传感器激酶 phoQ 基因会降低植物促生根瘤菌 Rahnella aquatilis HX2 的耐酸性。

Disruption of the sensor kinase phoQ gene decreases acid resistance in plant growth-promoting rhizobacterium Rahnella aquatilis HX2.

机构信息

College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China.

Beijing Key Laboratory of Biodiversity and Organic Farming, China Agricultural University, Beijing 100193, China.

出版信息

J Appl Microbiol. 2023 Feb 16;134(2). doi: 10.1093/jambio/lxad009.

DOI:10.1093/jambio/lxad009

PMID:36748653

Abstract

AIMS

Rahnella aquatilis HX2, a promising plant growth-promoting rhizobacterium (PGPR) in the field, contains genes homologous to the PhoP/PhoQ two-component regulatory system. Although this system regulates stress response in numerous pathogens, PhoP/PhoQ characterization in a PGPR has not received in-depth exploration.

METHODS AND RESULTS

The phoQ gene was mutated in strain HX2 using an in-frame deletion strategy. Compared to the wild type, the phoQ mutant exhibited increased sensitivity to acidic conditions (pH 4.0) in a chemically defined medium and in mild acidic natural soil (pH 5.7). The phoQ mutant also exhibited increased swimming motility under acidic conditions. Acid resistance was restored in the mutant by introducing the phoQ gene on a plasmid. Three acid resistance genes, add, cfa, and fur were downregulated significantly, whereas the chaperone encoding gene, dnak, was upregulated when the phoQ mutant was exposed to acid stress.

CONCLUSIONS

This study suggested that the PhoP/PhoQ system positively regulates the acid resistance of R. aquatilis HX2.

摘要

目的

水生拉恩氏菌 HX2 是一种有前途的植物促生根际细菌（PGPR），其含有与 PhoP/PhoQ 双组分调控系统同源的基因。尽管该系统在许多病原体中调节应激反应，但 PGPR 中的 PhoP/PhoQ 特性尚未得到深入探讨。

方法和结果

利用框内缺失策略在菌株 HX2 中突变 phoQ 基因。与野生型相比，在化学定义培养基和温和酸性天然土壤（pH5.7）中，phoQ 突变体对酸性条件（pH4.0）的敏感性增加。在酸性条件下，phoQ 突变体的泳动性也增加。在突变体中通过质粒引入 phoQ 基因可恢复其耐酸性。当 phoQ 突变体暴露于酸性胁迫时，三个耐酸基因 add、cfa 和 fur 显著下调，而伴侣蛋白编码基因 dnak 上调。