Elucidating the molecular basis of effector-triggered host susceptibility mediated by the TAL-like effector Brg11 from the bacterial pathogen Ralstonia solanacearum

阐明细菌病原体青枯菌中 TAL 样效应子 Brg11 介导的效应子触发宿主易感性的分子基础

• 批准号: 413908990
• 负责人: Professor Dr. Thomas Lahaye
• 金额: --
• 依托单位: Abteilung für Allgemeine Genetik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/413908990?language=en
• 关键词: Elucidating; molecular; basis; effector; triggered

Plant pathogens pose a permanent thread to global food security. To invade plants, phytopathogenic microbes rely on effector proteins that they inject into host cells to promote host susceptibility. Knowledge of effector targets inside host cells provides a possibility for knowledge-based breeding of pest-resistant crops. Thus, elucidation of the molecular basis of effector-triggered host susceptibility remains a major aim of fundamental and applied plant pathology.We study Ralstonia solanacearum a devastating bacterial pathogen that triggers bacterial wilt disease on numerous crop species. We have characterized Brg11, a R. solanacearum effector with high similarity to transcription activator-like effectors (TALEs) from the bacterial genus Xanthomonas. TALEs bind to effector binding elements (EBEs) present in host promoters and transcriptionally activate downstream host susceptibility (S) genes to promote disease. Given its relatedness to TALEs it’s conceivable that Brg11 promotes disease by transcriptional activation of host S genes. Thus, we aimed to identify host genes that are transcriptionally activated by Brg11 to clarify how it promotes disease.To identify Brg11 host target genes we determined a preferred target sequence of Brg11 (Brg11-EBE). A 18bp-motif resembling Brg11-EBE was identified upstream of all arginine decarboxylase (ADC) genes in R. solanacearum host genomes and accordingly this motif was designated as ADC-box. Combined analysis of RNA-Seq data and target site prediction suggests that ADC1 and ADC2 are the only direct target genes of Brg11 in tomato. Inspection of Brg11-induced versus intrinsic ADC transcripts revealed short (100 bps) and long (450 bps) 5’UTRs, respectively. Preliminary data suggest that differences in their 5’UTRs cause that translation of intrinsic but not Brg11-induced transcripts is feedback regulated by metabolites that accumulate due to activity of ADC enzymes. Thus, Brg11-induced ADC transcripts likely evade translational control mechanisms that limit translation from intrinsic transcripts. In summary, our findings suggest that R. solanacearum Brg11 promotes bacterial wilt disease by transcriptional activation of host ADC genes.In the framework of this proposal we aim to:- study translational regulation of intrinsic versus Brg11-induced ADC transcripts- establish a catalogue of metabolites that change as consequence of elevated ADC protein levels- Analyze growth-inhibiting/promoting activity of Brg11-induced metabolites on plant associated microbes- Establish cellular reporters to visualize Brg11 target cells and Brg11-induced changes- Investigate Brg11-induced changes at the transcriptional and translational levelIn summary, these studies shall provide insights into how Brg11-induced activation of ADC genes promotes bacterial wilt disease.

植物病原体对全球粮食安全构成永久威胁。为了入侵植物，植物病原微生物依赖于它们注入宿主细胞以促进宿主易感性的效应蛋白。对宿主细胞内效应靶点的了解为基于知识的抗虫作物育种提供了可能性。因此，阐明效应子触发的宿主易感性的分子基础仍然是基础和应用plant pathology.We研究Ralstonia solanacearum一种毁灭性的细菌病原体，引发细菌性枯萎病在许多作物物种的主要目标。我们对R.与来自细菌黄单胞菌属的转录激活因子样效应子（TALE）具有高度相似性的青枯菌效应子。TALE与宿主启动子中存在的效应子结合元件（EBE）结合，并转录激活下游宿主易感性（S）基因以促进疾病。鉴于其与TALE的相关性，可以想象Brg 11通过宿主S基因的转录激活促进疾病。因此，我们的目的是确定宿主基因的转录激活的Brg 11，以澄清它如何促进diseases.To确定Brg 11宿主靶基因，我们确定了一个首选的目标序列的Brg 11（Brg 11-EBE）。在所有的精氨酸脱羧酶（ADC）基因上游都发现了一个类似Brg 11-EBE的18 bp基序。因此，将该基序命名为ADC盒。RNA-Seq数据和靶位点预测的结合分析表明，ADC 1和ADC 2是Brg 11在番茄中的唯一直接靶基因。对Brg 11诱导的ADC转录物与内在ADC转录物的检查分别显示短（100 bps）和长（450 bps）的5 'UTR。初步数据表明，其5 'UTR的差异导致内源性而非Brg 11诱导的转录物的翻译受到ADC酶活性导致的代谢物积累的反馈调节。因此，Brg 11诱导的ADC转录物可能逃避限制内在转录物翻译的翻译控制机制。综上所述，我们的研究结果表明，R。青枯菌Brg 11通过宿主ADC基因的转录激活促进青枯病的发生。- 研究内在的相对于Brg 11诱导的ADC转录物的翻译调节-建立作为ADC蛋白水平升高的结果而改变的代谢物的目录-分析Brg 11诱导的代谢物对植物相关微生物的生长抑制/促进活性-建立细胞报告子以可视化Brg 11靶细胞和Brg 11诱导的变化-在转录和翻译水平上研究Brg 11诱导的变化总之，这些研究将提供Brg 11诱导的ADC基因激活如何促进细菌性枯萎病的见解。