Elucidating in planta target genes of Ralstonia solanacearum TALE-like proteins

青枯病病原菌青枯病是美国和欧盟的检疫性生物，是农作物中最具破坏性的微生物之一。我们的目标是在分子水平上研究青枯病菌与寄主植物之间的相互作用，并期望从长远来看，我们的发现将使我们能够开发出有效的对策来对抗这种毁灭性的病原菌。由细菌病原体注入宿主细胞的效应蛋白要么促进疾病，要么触发植物免疫。因此，它们是植物-微生物相互作用结果的关键决定因素。在这个建议的框架内，我们将研究RipTALs，这是青枯菌中广泛存在的一类效应器，它与细菌黄单胞菌属的转录激活器样效应器(TALE)具有同源性。TALE代码描述了给定故事DNA结合域中定义的氨基酸与其效应器结合元件(EBE)中特定DNA碱基的相关性。这允许对已知序列的故事进行EBE的电子预测。在初步研究中，我们表明，就像故事一样，RipTAL EBE可以用故事代码来预测。此外，像TALS一样，RipTALs被注射到宿主细胞中，并能够转录激活带有预测的EBE的启动子。因此，可以想象，RipTALs和TALS一样，通过转录激活宿主基因来促进宿主植物的易感性。鉴于青枯病菌是一种根部病原菌，而黄单胞菌通常侵染气生组织，可以想象它们通过激活寄主易感性(S)基因来促进疾病，这些基因编码功能不同的蛋白质。我们的目标是鉴定RipTAL激活的宿主S基因，当特定的RipTAL转录上调时，促进细菌疾病的基因。一旦宿主S基因被分离和功能验证，我们就想从分子水平上阐明S基因产物是如何促进青枯病菌发病的。青枯病菌从世界各地分离的菌株可以分为四个系统型，这与它们的地理起源有关。值得注意的是，青枯病菌系统类型I、II和IV包含的RipTAL在其N-末端和C-末端区域以及它们预测的EBE上都不同。到目前为止，对RipTALs的分子研究主要集中在I型RipTALs上。在本研究的框架内，我们的目标是也研究I型和IV型菌株的RipTALs，长期目标是鉴定和鉴定相应的寄主S基因和基因产物。综上所述，我们的目标是从不同的青枯病菌系统型中鉴定和鉴定RipTALs激活的寄主S基因。我们期待我们的发现将为青枯病的防治策略提供深入的见解，有助于开发有效的对策来保护作物。

Ralstonia solanacearum, the causal agent of bacterial wilt disease, is a quarantine organism in the USA and EU that ranks among the most devastating microbial pathogens in crop plants. We aim to study the interaction between R. solanacearum and its host plants at the molecular level and anticipate that our findings will enable us, in the long run, to develop effective countermeasures against this devastating pathogen. The effector proteins injected by bacterial pathogens into host cells either promote disease or trigger plant immunity. They are thus key determinants for the outcome of plant-microbe interactions. In the framework of this proposal we will study RipTALs, one class of effectors that are widespread in R. solanacearum and that share homology with Transcription Activator Like Effectors (TALEs) from the bacterial genus Xanthomonas.The TALE code describes the correlation of defined amino acids in a given TALE DNA binding domain with specific DNA bases in its effector binding element (EBE). This allows in silico prediction of EBEs for TALEs of known sequence. In preliminary studies we showed that, like for TALEs, RipTAL EBEs can be predicted with the TALE code. Furthermore RipTALs, like TALEs are injected into host cells and are capable of transcriptionally activating promoters bearing a predicted EBE. It is thus conceivable that RipTALs, like TALEs, transcriptionally activate host genes to promote susceptibility in host plants. Given that R. solanacearum is a root pathogen, while xanthomonads typically infect aerial tissues, it is conceivable that they promote disease by activation of host susceptibility (S) genes that encode functionally distinct proteins.We aim to identify RipTAL activated host S genes that promote bacterial disease when being transcriptionally upregulated by a given RipTAL. Once host S genes have been isolated and functionally validated we want to clarify how S gene products promote R. solanacearum disease at the molecular level.R. solanacearum strains isolated from all over the world can be subdivided into four phylotypes, which correlate with their geographical origin. Notably R. solanacearum phylotypes I, II and IV contain RipTALs that differ in their N- and C-terminal regions and their predicted EBEs. Till now molecular studies of RipTALs have been conducted almost exclusively on RipTALs from phylotype I. In the framework of this proposal we aim to also characterize RipTALs from phylotype II and IV strains with the long term goal to identify and characterize corresponding host S genes and gene products.In summary we aim to identify and characterize host S genes that are activated by RipTALs from diverse R. solanacearum phylotypes. We anticipate that our findings will provide insights into the disease strategies of R. solanacearum, aiding the development of efficient countermeasures to protect crop plants.