Little Richard H, Woodcock Stuart D, Campilongo Rosaria, Fung Rowena K Y, Heal Robert, Humphries Libby, Pacheco-Moreno Alba, Paulusch Stefan, Stigliano Egidio, Vikeli Eleni, Ward Danny, Malone Jacob G
Department of Molecular Microbiology, John Innes Centre, Norwich, United Kingdom.
Internal Medicine, Universitätsklinikum Bonn, Bonn, Germany.
Front Microbiol. 2019 May 16;10:1089. doi: 10.3389/fmicb.2019.01089. eCollection 2019.
Bacteria belonging to the genus are highly successful colonizers of the plant rhizosphere. The ability of different species to live either commensal lifestyles or to act as agents of plant-growth promotion or disease is reflected in a large, highly flexible accessory genome. Nevertheless, adaptation to the plant environment involves a commonality of phenotypic outputs such as changes to motility, coupled with synthesis of nutrient uptake systems, stress-response molecules and adherence factors including exopolysaccharides. Cyclic-di-GMP (cdG) is a highly important second messenger involved in the integration of environmental signals with appropriate adaptive responses and is known to play a central role in mediating effective rhizosphere colonization. In this study, we examined the transcription of multiple, reportedly plant-upregulated cdG metabolism genes during colonization of the wheat rhizosphere by the plant-growth-promoting strain SBW25. While transcription of the tested genes generally increased in the rhizosphere environment, we additionally observed a tightly orchestrated response to environmental cues, with a distinct transcriptional pattern seen for each gene throughout the colonization process. Extensive phenotypical analysis of deletion and overexpression strains was then conducted and used to propose cellular functions for individual cdG signaling genes. Finally, in-depth genetic analysis of an important rhizosphere colonization regulator revealed a link between cdG control of growth, motility and stress response, and the carbon sources available in the rhizosphere.
属于该属的细菌是植物根际非常成功的定殖者。不同物种以共生方式生活或作为植物生长促进剂或病原体的能力反映在一个庞大、高度灵活的辅助基因组中。然而，对植物环境的适应涉及表型输出的共性，如运动性的变化，以及营养吸收系统、应激反应分子和包括胞外多糖在内的粘附因子的合成。环二鸟苷酸（cdG）是一种非常重要的第二信使，参与将环境信号与适当的适应性反应整合，并且已知在介导有效的根际定殖中起核心作用。在本研究中，我们检测了植物生长促进菌株SBW25在小麦根际定殖过程中多个据报道在植物中上调的cdG代谢基因的转录情况。虽然测试基因的转录在根际环境中总体上增加，但我们还观察到对环境线索的紧密协调反应，在整个定殖过程中每个基因都有独特的转录模式。然后对缺失和过表达菌株进行了广泛的表型分析，并用于推测单个cdG信号基因的细胞功能。最后，对一个重要的根际定殖调节因子进行深入的遗传分析，揭示了cdG对生长、运动性和应激反应的控制与根际中可用碳源之间的联系。
