State Key Laboratory of Rice Biology, Ministry of Agriculture Key Lab of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, 310058, Hangzhou, China; Department of Crop Protection, Federal University of Agriculture Abeokuta, Abeokuta, Nigeria.
State Key Laboratory of Rice Biology, Ministry of Agriculture Key Lab of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, 310058, Hangzhou, China.
Microb Pathog. 2019 Jan;126:343-350. doi: 10.1016/j.micpath.2018.11.017. Epub 2018 Nov 20.
Type IV secretion system (T4SS) is a specialized nanomachine that is utilized for the pathogenicity of gram-negative bacteria. However, the role of T4SS genes in virulence of rice bacterial brown stripe pathogen Acidovorax oryzae (Ao) strain RS-2 is not clear, which contains T4SS gene cluster based on genome-wide analysis. Here we compared the virulence-related phenotypes between the wild-type strain RS-2 and nine T4SS mutants, which were constructed in this study. Results indicated that mutation of pilT, pilM, pilQ, or pilZ3 genes not only significantly reduced bacterial virulence, but also caused a reduction of 20.4-62.0% in biofilm formation and 37.7-47.7% reduction in motility, but had no effect on exopolysaccharide (EPS) production or extracellular enzymatic activities when compared to the wild type. The four T4SS genes had a differential effect on bacterial growth after 24 h post-incubation. The complemented strains of the four T4SS mutants restored similar virulence symptom as the wild type. In addition, no change was observed in bacterial virulence by mutation of the other five T4SS genes. Totally, these results demonstrated that T4SS played vital roles in bacterial virulence, motility and biofilm formation in plant pathogen Ao strain RS-2.
IV 型分泌系统（T4SS）是一种专门的纳米机器，用于革兰氏阴性菌的致病性。然而，T4SS 基因在水稻细菌性条斑病菌（Ao）菌株 RS-2 毒力中的作用尚不清楚，该菌株基于全基因组分析含有 T4SS 基因簇。在这里，我们比较了野生型菌株 RS-2 和本研究构建的九个 T4SS 突变体之间的与毒力相关的表型。结果表明，pilT、pilM、pilQ 或 pilZ3 基因突变不仅显著降低了细菌的毒力，而且还导致生物膜形成减少了 20.4-62.0%，运动性降低了 37.7-47.7%，而与野生型相比，对胞外多糖（EPS）的产生或细胞外酶活性没有影响。这四个 T4SS 基因在孵育 24 小时后对细菌生长有不同的影响。四个 T4SS 突变体的互补菌株恢复了与野生型相似的毒力症状。此外，突变其他五个 T4SS 基因对细菌毒力没有影响。总的来说，这些结果表明 T4SS 在植物病原菌 Ao 菌株 RS-2 的细菌毒力、运动性和生物膜形成中起着至关重要的作用。
