Control strategies and dynamic gene expression in plant pathogen ralstonia solanacearum
- Autores: Marina Puigvert Sanchez
- Directores de la Tesis: Marc Valls (dir. tes.)
- Lectura: En la Universitat de Barcelona ( España ) en 2018
- Idioma: español
- Tribunal Calificador de la Tesis: Fabienne Vailleau (presid.), Carlos Balsalobre Parra (secret.), Carmen Rosario Beuzon Lopez (voc.)
- Programa de doctorado: Programa de Doctorado en Genética por la Universidad de Barcelona
- Materias:
- Enlaces
- Tesis en acceso abierto en: TDX
- Resumen
he plant pathogen Ralstonia solanacearum is the causal agent of bacterial wilt, a highly aggressive disease responsible for important worldwide economic losses. Many virulence factors in R. solanacearum have been already identified; however, their transcriptional regulation during disease development remained unknown.
In an effort to better characterize the gene expression changes driving bacterial virulence, we first provided the complete genome sequence of the potato R. solanacearum UY031 strain as a tool to perform robust transcriptomics in planta. By taking advantage of the novel sequencing technology called SMRT, we also supplied hints on the methylome profile and its contribution to virulence gene expression in UY031.
In this work, we performed two different in planta transcriptome approaches at different potato infection stages. On one hand, we analyzed the bacterial gene expression during root colonization and demonstrated that, although it is cost-ineffective, microbial transcriptomes in planta at low bacterial densities are possible without a prior enrichment of prokaryotic RNA. Furthermore, we identified a novel player controlling bacterial fitness during early infection stages that we named RepR for Repressor Regulator, since we discovered that it is a repressor of specific metabolic pathways. On the other hand, we performed a time-course transcriptome and show that expression of R. solanacearum virulence factors and metabolism is dynamic along the infection process. With our system, we validated the expression patterns of known virulence factors such as the Type III Secretion System (T3SS) or the flagellum, and unraveled the profiles of others like Type IVb pili or the T6SS. Contrary to the assumption that the T3SS might play only a role at early infection stages, we demonstrate that effector transcription is extremely high in advanced disease stages.
Finally, we performed a pilot test to identify T3SS inhibitors and demonstrate that some salicylidene acylhydrazides can potentially prevent bacterial plant diseases via T3SS transcription inhibition. This work adds growing knowledge on the pathogen behavior and its physiology at different points of the disease, which could eventually lead to the identification of new drugs targeting keys steps in disease development.
