In Vitro and In Vivo Secretion/Translocation Assays to Identify Novel Ralstonia solanacearum Type 3 Effectors

Lonjon, Fabien; Peeters, Nemo; Genin, Stéphane; Vailleau, Fabienne

doi:10.1007/978-1-4939-7604-1_17

Cited by 11 publications

(9 citation statements)

References 29 publications

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“…Regulation‐based strategies include gene expression studies (Cunnac et al ., 2004b; Occhialini et al ., 2005) and genetic screens using random transposon‐insertion mutagenesis (Mukaihara et al ., 2004). Verification of the T3SS‐dependency of the secretion or translocation is typically required to confirm the bona fide T3E status of in silico predicted or candidate T3Es (Lonjon et al ., 2018). Most translocation analyses exploit the adenylate cyclase (Cya) reporter system (Cunnac et al ., 2004b; Mukaihara and Tamura, 2009; Mukaihara et al ., 2010).…”

Section: The Rssc Type III Effectome a Large And Varied Arsenalmentioning

confidence: 99%

The large, diverse, and robust arsenal of Ralstonia solanacearum type III effectors and their in planta functions

Landry

González‐Fuente

Deslandes

et al. 2020

Molecular Plant Pathology

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The type III secretion system with its delivered type III effectors (T3Es) is one of the main virulence determinants of Ralstonia solanacearum, a worldwide devastating plant pathogenic bacterium affecting many crop species. The pan‐effectome of the R. solanacearum species complex has been exhaustively identified and is composed of more than 100 different T3Es. Among the reported strains, their content ranges from 45 to 76 T3Es. This considerably large and varied effectome could be considered one of the factors contributing to the wide host range of R. solanacearum. In order to understand how R. solanacearum uses its T3Es to subvert the host cellular processes, many functional studies have been conducted over the last three decades. It has been shown that R. solanacearum effectors, as those from other plant pathogens, can suppress plant defence mechanisms, modulate the host metabolism, or avoid bacterial recognition through a wide variety of molecular mechanisms. R. solanacearum T3Es can also be perceived by the plant and trigger immune responses. To date, the molecular mechanisms employed by R. solanacearum T3Es to modulate these host processes have been described for a growing number of T3Es, although they remain unknown for the majority of them. In this microreview, we summarize and discuss the current knowledge on the characterized R. solanacearum species complex T3Es.

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Section: The Rssc Type III Effectome a Large And Varied Arsenalmentioning

confidence: 99%

The large, diverse, and robust arsenal of Ralstonia solanacearum type III effectors and their in planta functions

Landry

González‐Fuente

Deslandes

et al. 2020

Molecular Plant Pathology

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“…With the development of genomics, an increasing number of R. solanacearum strains have been sequenced, and a plethora of effectors have been identified (Burstein et al ., , Peeters et al ., ; Petnickiocwieja et al ., ). Currently, more than 100 effectors have been reported in the R. solanacearum species complex (Deslandes and Genin, ; Lonjon et al ., ; Peeters et al ., ). Hence, a larger scale functional screening of effectors is essential for both the provision of more basic information on the effector inventory and acceleration of research on host resistance.…”

Section: Introductionmentioning

confidence: 99%

“…Compared with Pseudomonas and Xanthomonas , Ralstonia harbours a larger effector repertoire of approximately 110 members (Lonjon et al ., ; Peeters et al ., ). To date, the biochemical functions of a small number of these effectors and their targets have been described.…”

Section: Introductionmentioning

confidence: 99%

A systematic screen of conserved Ralstonia solanacearum effectors reveals the role of RipAB, a nuclear‐localized effector that suppresses immune responses in potato

Zheng

Wang

et al. 2019

Molecular Plant Pathology

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Summary Both Solanum tuberosum and Ralstonia solanacearum phylotype IIB originated in South America and share a long‐term co‐evolutionary history. However, our knowledge of potato bacterial wilt pathogenesis is scarce as a result of the technical difficulties of potato plant manipulation. Thus, we established a multiple screening system (virulence screen of effector mutants in potato, growth inhibition of yeast and transient expression in Nicotiana benthamiana ) of core type III effectors (T3Es) of a major potato pathovar of phylotype IIB, to provide more research perspectives and biological tools. Using this system, we identified four effectors contributing to virulence during potato infection, with two exhibiting multiple phenotypes in two other systems, including RipAB. Further study showed that RipAB is an unknown protein with a nuclear localization signal (NLS). Furthermore, we generated a ripAB complementation strain and transgenic ripAB ‐expressing potato plants, and subsequent virulence assays confirmed that R. solanacearum requires RipAB for full virulence. Compared with wild‐type potato, transcriptomic analysis of transgenic ripAB ‐expressing potato plants showed a significant down‐regulation of Ca 2+ signalling‐related genes in the enriched Plant–Pathogen Interaction (PPI) gene ontology (GO) term. We further verified that, during infection, RipAB is required for the down‐regulation of four Ca 2+ sensors, Stcml5 , Stcml23 , Stcml‐cast and Stcdpk2 , and a Ca 2+ transporter, Stcngc1 . Further evidence showed that the immune‐associated reactive oxygen species (ROS) burst is attenuated in ripAB transgenic potato plants. In conclusion, a systematic screen of conserved R. solanacearum effectors revealed an important role for RipAB, which interferes with Ca 2+ ‐dependent gene expression to promote disease development in potato.

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“…The final expression vectors were transformed into the R. pseudosolanacearum GMI1000 strain and in the hrcV mutant (type III secretion defective mutant, used as a negative control) as previously described (Perrier, Barberis & Genin, 2018). In-vitro secretion assays and western blot analysis were performed as previously described (Lonjon et al, 2018).…”

Section: Methodsmentioning

confidence: 99%

Pangenomic type III effector database of the plant pathogenicRalstoniaspp.

Sabbagh

Carrère

Lonjon

et al. 2019

PeerJ

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Background The bacterial plant pathogenic Ralstonia species belong to the beta-proteobacteria class and are soil-borne pathogens causing vascular bacterial wilt disease, affecting a wide range of plant hosts. These bacteria form a heterogeneous group considered as a “species complex” gathering three newly defined species. Like many other Gram negative plant pathogens, Ralstonia pathogenicity relies on a type III secretion system, enabling bacteria to secrete/inject a large repertoire of type III effectors into their plant host cells. Type III-secreted effectors (T3Es) are thought to participate in generating a favorable environment for the pathogen (countering plant immunity and modifying the host metabolism and physiology). Methods Expert genome annotation, followed by specific type III-dependent secretion, allowed us to improve our Hidden-Markov-Model and Blast profiles for the prediction of type III effectors. Results We curated the T3E repertoires of 12 plant pathogenic Ralstonia strains, representing a total of 12 strains spread over the different groups of the species complex. This generated a pangenome repertoire of 102 T3E genes and 16 hypothetical T3E genes. Using this database, we scanned for the presence of T3Es in the 155 available genomes representing 140 distinct plant pathogenic Ralstonia strains isolated from different host plants in different areas of the globe. All this information is presented in a searchable database. A presence/absence analysis, modulated by a strain sequence/gene annotation quality score, enabled us to redefine core and accessory T3E repertoires.

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In Vitro and In Vivo Secretion/Translocation Assays to Identify Novel Ralstonia solanacearum Type 3 Effectors

Cited by 11 publications

References 29 publications

The large, diverse, and robust arsenal of Ralstonia solanacearum type III effectors and their in planta functions

The large, diverse, and robust arsenal of Ralstonia solanacearum type III effectors and their in planta functions

A systematic screen of conserved Ralstonia solanacearum effectors reveals the role of RipAB, a nuclear‐localized effector that suppresses immune responses in potato

Pangenomic type III effector database of the plant pathogenicRalstoniaspp.

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