Yu Chao, Nguyen Doan-Phuong, Yang Fenghuan, Shi Jia, Wei Yiming, Tian Fang, Zhao Xiuxiang, Chen Huamin
State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.
College of Plant Protection, Shenyang Agricultural University, Shenyang, China.
Front Microbiol. 2021 Mar 4;12:653354. doi: 10.3389/fmicb.2021.653354. eCollection 2021.
σ factor (RpoN) plays a crucial role in bacterial motility, virulence, growth, and other biological functions. In our previous study, two homologous σ factors, RpoN1 and RpoN2, were identified in pv. (), the causative agent of bacterial leaf blight in rice. However, their functional roles, i.e., whether they exert combined or independent effects, remain unknown. In the current study, or deletion in significantly disrupted bacterial swimming motility, flagellar assembly, and virulence. Transcriptome analysis led to the identification of 127 overlapping differentially expressed genes (DEGs) regulated by both RpoN1 and RpoN2. Furthermore, GO and KEGG classification demonstrated that these DEGs were highly enriched in flagellar assembly, chemotaxis, and c-di-GMP pathways. Interestingly, deletion decreased transcription, while deletion did not affect transcription. No interaction between the promoter and RpoN1 was detected, suggesting that RpoN1 indirectly regulates transcription. In addition, RpoN1-regulated DEGs were specially enriched in ribosome, carbon, and nitrogen metabolism pathways. Besides, bacterial growth was remarkably repressed in Δ but not in Δ. Taken together, this study demonstrates the overlapping and unique regulatory roles of RpoN1 and RpoN2 in motility, virulence, growth and provides new insights into the regulatory mechanism of σ factors in .
σ因子（RpoN）在细菌运动性、毒力、生长及其他生物学功能中发挥着关键作用。在我们之前的研究中，在水稻白叶枯病病原菌（）中鉴定出了两个同源σ因子RpoN1和RpoN2。然而，它们的功能作用，即它们是发挥联合作用还是独立作用，仍然未知。在当前研究中，（）中RpoN1或RpoN2的缺失显著破坏了细菌的游动性、鞭毛组装及毒力。转录组分析导致鉴定出了127个受RpoN1和RpoN2共同调控的重叠差异表达基因（DEG）。此外，基因本体（GO）和京都基因与基因组百科全书（KEGG）分类表明，这些DEG在鞭毛组装、趋化性和环二鸟苷酸（c-di-GMP）途径中高度富集。有趣的是，RpoN1缺失降低了（）的转录，而RpoN2缺失不影响（）的转录。未检测到（）启动子与RpoN1之间的相互作用，这表明RpoN1间接调控（）的转录。此外，RpoN1调控的DEG在核糖体、碳和氮代谢途径中特别富集。此外，（）中细菌生长受到显著抑制，而（）中则没有。综上所述，本研究证明了RpoN1和RpoN2在运动性、毒力、生长方面的重叠和独特调控作用，并为（）中σ因子的调控机制提供了新的见解。
