荧光假单胞菌2P24中(p)ppGpp结合TrmE蛋白调控PcoI/PcoR群体感应系统

doi:10.1016/j.jia.2024.09.031

Journal of Integrative Agriculture ›› 2026, Vol. 25 ›› Issue (6): 2462-2474.DOI: 10.1016/j.jia.2024.09.031

荧光假单胞菌2P24中(p)ppGpp结合TrmE蛋白调控PcoI/PcoR群体感应系统

收稿日期:2024-06-12 修回日期:2024-09-26 接受日期:2024-08-11 出版日期:2026-06-20 发布日期:2026-05-06

(p)ppGpp interacts with TrmE and regulates the PcoI/PcoR quorum-sensing system of Pseudomonas fluorescens 2P24

Ruijing Shang¹, Shihai Liang¹, Qing Yan², Bingxin Wang³, Guoliang Qian³, Lang Yang⁴, Xiaogang Wu¹^*

¹Guangxi Key Laboratory of Agro-Environment and Agro-Product Safety/College of Agriculture, Guangxi University, Nanning 530004, China
² Department of Plant Sciences and Plant Pathology, Montana State University, Bozeman 59717, USA
³College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
⁴ Institute of Plant Protection, Guangxi Academy of Agricultural Sciences, Nanning 530007, China

Received:2024-06-12 Revised:2024-09-26 Accepted:2024-08-11 Online:2026-06-20 Published:2026-05-06
About author:#Correspondence Xiaogang Wu, Tel/Fax: +86-771-3235643, E-mail: wux@gxu.edu.cn
Supported by:
The authors would like to thank Dr. Liqun Zhang from China Agricultural University, for sharing bacteria strains. This work was supported by the Natural Science Foundation of Guangxi, China (2021GXNSFDA220006) and the Guangxi Key Laboratory of Agro-Environment and Agro-Product Safety Open Projects Fund, China (GKLAEAPS2023-04).

摘要/Abstract

摘要：

[目的]植物有益假单胞菌（Pseudomonas spp.）在植物根围的有效定殖是其发挥生防功能的先决条件，而前期研究表明荧光假单胞菌（P. fluorescens）2P24中PcoI/PcoR群体感应（quorum sensing；QS）系统正调控其在植物根围的定殖。定殖过程中，菌株2P24会受到植物来源活性氧和其他环境胁迫的多重影响，但不利环境条件影响QS系统的分子机制尚不清楚。[方法]以菌株2P24为出发菌，通过同源重组技术构建了relA突变体、spoT突变体和relA spoT双突变体。利用转录融合等技术检测了(p)ppGpp合成酶RelA和(p)ppGpp合成酶/水解酶SpoT对QS系统的调控作用；微量热泳动技术检测了(p)ppGpp与TrmE蛋白互作关系。[结果]菌株2P24中同时缺失spoT和relA基因可显著提高QS系统中信号合成基因pcoI的表达，而缺失spoT基因则显著抑制pcoI基因的表达。遗传学和微量热泳动试验表明TrmE蛋白（一种tRNA修饰GTP酶）可结合(p)ppGpp且是(p)ppGpp调控QS系统所必需的遗传因子。此外，spoT和relA基因还参与菌株2P24中游动性、生物膜形成、氧化应激、渗透耐受性和根围定殖等多种生防相关性状。[结论]菌株2P24中relA基因和spoT基因介导的(p)ppGpp信号通路对QS系统的功能起重要调控作用，并对研究生防菌株通过(p)ppGpp调控通路影响其定殖能力的分子机制具有重要意义。

Abstract:

The efficient colonization of plant-beneficial Pseudomonas spp. is a prerequisite for their biocontrol capacity. Prior work revealed that the PcoI/PcoR quorum-sensing (QS) system plays a pivotal role in the root colonization of P. fluorescens 2P24. During the colonization, strain 2P24 has faced diverse impacts from plant-derived reactive oxygen species and other environmental stress. However, the molecular mechanism by which the PcoI/PcoR QS system is regulated under unfavored conditions remains unclear. Thus, in this study, the role of the (p)ppGpp synthetase RelA and the bifunctional (p)ppGpp synthase/hydrolase SpoT in the PcoI/PcoR QS system of P. fluorescens was investigated. Our data indicated that the deficiency of relA and spoT genes remarkably improved the expression of the pcoI gene, whereas the mutation of the spoT gene significantly repressed the expression of the pcoI gene. We further demonstrated that the regulation of the PcoI/PcoR QS system by (p)ppGpp was dependent on the function of the trmE gene, which encodes a tRNA modification GTPase. Furthermore, the mutation of relA, spoT, or both significantly influenced the motility, biofilm formation, oxidative stress, osmotic tolerance, and rhizosphere colonization. Collectively, our data indicated that the (p)ppGpp signaling pathway mediated by the relA gene and spoT gene was important to the function of the PcoI/PcoR QS system and had important implications for the understanding of the molecular mechanism of (p)ppGpp in epiphytic fitness via TrmE of P. fluorescens.

Key words: Pseudomonas fluorescens , quorum sensing , relA , spoT , trmE

Ruijing Shang, Shihai Liang, Qing Yan, Bingxin Wang, Guoliang Qian, Lang Yang, Xiaogang Wu. 荧光假单胞菌2P24中(p)ppGpp结合TrmE蛋白调控PcoI/PcoR群体感应系统[J]. Journal of Integrative Agriculture, 2026, 25(6): 2462-2474.

Ruijing Shang, Shihai Liang, Qing Yan, Bingxin Wang, Guoliang Qian, Lang Yang, Xiaogang Wu. (p)ppGpp interacts with TrmE and regulates the PcoI/PcoR quorum-sensing system of Pseudomonas fluorescens 2P24[J]. Journal of Integrative Agriculture, 2026, 25(6): 2462-2474.

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荧光假单胞菌2P24中(p)ppGpp结合TrmE蛋白调控PcoI/PcoR群体感应系统

(p)ppGpp interacts with TrmE and regulates the PcoI/PcoR quorum-sensing system of Pseudomonas fluorescens 2P24

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