Guangxi Key Laboratory of Agro-Environment and Agro-Product Safety/College of Agriculture, Guangxi Universitygrid.256609.e, Nanning, China.
College of Plant Protection, China Agricultural Universitygrid.22935.3f, Beijing, China.
Appl Environ Microbiol. 2022 Jul 12;88(13):e0062522. doi: 10.1128/aem.00625-22. Epub 2022 Jun 13.
Pseudomonas fluorescens 2P24 is a beneficial plant root-associated microorganism capable of suppressing several soilborne plant diseases. The capacity of P. fluorescens to aggressively colonize the rhizosphere is an important requirement for its biocontrol trait. We previously found that the PcoI/PcoR quorum-sensing system (QS) is involved in regulating the rhizosphere colonization of P. fluorescens. Here, we revealed a sophisticated regulatory network that connects PcoR, RsaL, and MvaT proteins to fine-tune the PcoI/PcoR QS system. Our data showed that PcoR could directly bind to the promoter region of thereby inducing the PcoI/PcoR QS system, whereas RsaL binds simultaneously with PcoR to the promoter region of and represses the PcoR-dependent activation of gene. In addition, RsaL indirectly downregulates the expression of . Furthermore, we showed that disruption of enhanced the expression of , , and , whereas MvaT controls the PcoI/PcoR QS in a RsaL-independent manner. Overall, this study elucidates that PcoR, RsaL, and MvaT regulate the PcoI/PcoR QS through a multi-tiered regulatory mechanism and that PcoR is necessary in the RsaL- and MvaT-mediated repression on the expression of . The PcoI/PcoR quorum-sensing system of Pseudomonas fluorescens 2P24 is important for its effective colonization in the plant rhizosphere. Many regulatory elements appear to directly or indirectly influence the QS system. Here, we found a complex regulatory network employing transcriptional factors PcoR, RsaL, and MvaT to influence the expression of the PcoI/PcoR QS in P. fluorescens 2P24. Our results indicate that PcoR and RsaL directly bind to the promoter region of and then positively and negatively regulate the expression of , respectively. Furthermore, the H-NS family protein MvaT negatively controls the PcoI/PcoR QS in a RsaL-independent manner. Taken together, our data provide new insights into the interplays between different regulatory elements that fine-tune the QS system of P. fluorescens.
荧光假单胞菌 2P24 是一种有益的植物根际相关微生物，能够抑制几种土传植物病害。荧光假单胞菌积极定殖根际的能力是其生物防治特性的重要要求。我们之前发现，PcoI/PcoR 群体感应系统 (QS) 参与调节荧光假单胞菌的根际定殖。在这里，我们揭示了一个复杂的调控网络，将 PcoR、RsaL 和 MvaT 蛋白连接起来，精细调节 PcoI/PcoR QS 系统。我们的数据表明，PcoR 可以直接结合到 的启动子区域，从而诱导 PcoI/PcoR QS 系统，而 RsaL 同时与 PcoR 结合到 的启动子区域，抑制 PcoR 依赖性的 基因激活。此外，RsaL 间接下调 的表达。此外，我们表明破坏 增强了 、 和 的表达，而 MvaT 以 RsaL 不依赖的方式控制 PcoI/PcoR QS。总的来说，这项研究阐明了 PcoR、RsaL 和 MvaT 通过多层次调控机制调节 PcoI/PcoR QS，并且 PcoR 是 RsaL 和 MvaT 介导的对 表达抑制所必需的。荧光假单胞菌 2P24 的 PcoI/PcoR 群体感应系统对其在植物根际的有效定殖很重要。许多调节元件似乎直接或间接地影响 QS 系统。在这里，我们发现了一个复杂的调控网络，利用转录因子 PcoR、RsaL 和 MvaT 来影响 P. fluorescens 2P24 中 PcoI/PcoR QS 的表达。我们的结果表明，PcoR 和 RsaL 直接结合到 的启动子区域，然后分别正向和负向调节 的表达。此外，H-NS 家族蛋白 MvaT 以 RsaL 不依赖的方式负调控 PcoI/PcoR QS。总之，我们的数据为不同调节元件之间的相互作用提供了新的见解，这些相互作用可以精细调节 P. fluorescens 的 QS 系统。
