Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Darwin 2, 28049 Madrid, Spain.
Department of Fundamental Microbiology, University of Lausanne, CH-1015 Lausanne, Switzerland.
Microb Genom. 2022 Jan;8(1). doi: 10.1099/mgen.0.000750.
Rhizosphere colonization by bacteria involves molecular and cellular mechanisms, such as motility and chemotaxis, biofilm formation, metabolic versatility, or biosynthesis of secondary metabolites, among others. Nonetheless, there is limited knowledge concerning the main regulatory factors that drive the rhizosphere colonization process. Here we show the importance of the AmrZ and FleQ transcription factors for adaption in the plant growth-promoting rhizobacterium (PGPR) and rhizosphere colonization model F113. RNA-Seq analyses of F113 grown in liquid cultures either in exponential and stationary growth phase, and rhizosphere conditions, revealed that rhizosphere is a key driver of global changes in gene expression in this bacterium. Regarding the genetic background, this work has revealed that a mutation in causes considerably more alterations in the gene expression profile of this bacterium than a mutation in under rhizosphere conditions. The functional analysis has revealed that in F113, the transcription factors AmrZ and FleQ regulate genes involved in diverse bacterial functions. Notably, in the rhizosphere, these transcription factors antagonistically regulate genes related to motility, biofilm formation, nitrogen, sulfur, and amino acid metabolism, transport, signalling, and secretion, especially the type VI secretion systems. These results define the regulon of two important bifunctional transcriptional regulators in pseudomonads during the process of rhizosphere colonization.
细菌的根际定殖涉及分子和细胞机制，例如运动性和趋化性、生物膜形成、代谢多功能性或次生代谢物的生物合成等。然而，对于驱动根际定殖过程的主要调节因子，我们的了解有限。在这里，我们展示了 AmrZ 和 FleQ 转录因子对于植物促生根际细菌（PGPR）和根际定殖模型 F113 适应的重要性。F113 在液体培养中无论是在指数生长期还是静止生长期以及根际条件下生长的 RNA-Seq 分析表明，根际是该细菌中全局基因表达变化的关键驱动因素。关于遗传背景，这项工作表明，与根际条件下的突变相比，突变导致该细菌的基因表达谱发生了更大的变化。功能分析表明，在 F113 中，转录因子 AmrZ 和 FleQ 调节涉及多种细菌功能的基因。值得注意的是，在根际中，这些转录因子拮抗地调节与运动性、生物膜形成、氮、硫和氨基酸代谢、运输、信号转导和分泌相关的基因，尤其是 VI 型分泌系统。这些结果定义了假单胞菌在根际定殖过程中两个重要双功能转录调节因子的调控组。
