Xanthomonas

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Lionel Gagnevin - One of the best experts on this subject based on the ideXlab platform.

  • crispr elements provide a new framework for the genealogy of the citrus canker pathogen Xanthomonas citri pv citri
    BMC Genomics, 2019
    Co-Authors: Kwanho Jeong, Lionel Gagnevin, Alejandra Munozbodnar, Nathalia Arias Rojas, Lucie Poulin, Luis M Rodriguezr, Christian Verniere
    Abstract:

    Xanthomonads are an important clade of Gram-negative bacteria infecting a plethora of economically important host plants, including citrus. Knowledge about the pathogen’s diversity and population structure are prerequisite for epidemiological surveillance and efficient disease management. Rapidly evolving genetic loci, such as Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR), are of special interest to develop new molecular typing tools. We analyzed CRISPR loci of 56 Xanthomonas citri pv. citri strains of world-wide origin, a regulated pathogen causing Asiatic citrus canker in several regions of the world. With one exception, 23 unique sequences built up the repertoire of spacers, suggesting that this set of strains originated from a common ancestor that already harbored these 23 spacers. One isolate originating from Pakistan contained a string of 14 additional, probably more recently acquired spacers indicating that this genetic lineage has or had until recently the capacity to acquire new spacers. Comparison of CRISPR arrays with previously obtained molecular typing data, such as amplified fragment length polymorphisms (AFLP), variable-number of tandem-repeats (VNTR) and genome-wide single-nucleotide polymorphisms (SNP), demonstrated that these methods reveal similar evolutionary trajectories. Notably, genome analyses allowed to generate a model for CRISPR array evolution in X. citri pv. citri, which provides a new framework for the genealogy of the citrus canker pathogen. CRISPR-based typing will further improve the accuracy of the genetic identification of X. citri pv. citri outbreak strains in molecular epidemiology analyses, especially when used concomitantly with another genotyping method.

  • a mlva genotyping scheme for global surveillance of the citrus pathogen Xanthomonas citri pv citri suggests a worldwide geographical expansion of a single genetic lineage
    PLOS ONE, 2014
    Co-Authors: Olivier Pruvost, Lionel Gagnevin, Maxime Magne, Karine Boyer, Alice Leduc, Christophe Tourterel, Christine Drevet, Virginie Ravigne, Fabien Guerin, Frederic Chiroleu
    Abstract:

    MultiLocus Variable number of tandem repeat Analysis (MLVA) has been extensively used to examine epidemiological and evolutionary issues on monomorphic human pathogenic bacteria, but not on bacterial plant pathogens of agricultural importance albeit such tools would improve our understanding of their epidemiology, as well as of the history of epidemics on a global scale. Xanthomonas citri pv. citri is a quarantine organism in several countries and a major threat for the citrus industry worldwide. We screened the genomes of Xanthomonas citri pv. citri strain IAPAR 306 and of phylogenetically related xanthomonads for tandem repeats. From these in silico data, an optimized MLVA scheme was developed to assess the global diversity of this monomorphic bacterium. Thirty-one minisatellite loci (MLVA-31) were selected to assess the genetic structure of 129 strains representative of the worldwide pathological and genetic diversity of X. citri pv. citri. Based on Discriminant Analysis of Principal Components (DAPC), four pathotype-specific clusters were defined. DAPC cluster 1 comprised strains that were implicated in the major geographical expansion of X. citri pv. citri during the 20th century. A subset of 12 loci (MLVA-12) resolved 89% of the total diversity and matched the genetic structure revealed by MLVA-31. MLVA-12 is proposed for routine epidemiological identification of X. citri pv. citri, whereas MLVA-31 is proposed for phylogenetic and population genetics studies. MLVA-31 represents an opportunity for international X. citri pv. citri genotyping and data sharing. The MLVA-31 data generated in this study was deposited in the Xanthomonas citri genotyping database (http://www.biopred.net/MLVA/). (Resume d'auteur)

  • polyphasic characterization of xanthomonads pathogenic to members of the anacardiaceae and their relatedness to species of Xanthomonas
    International Journal of Systematic and Evolutionary Microbiology, 2009
    Co-Authors: Nathalie Ahyou, Lionel Gagnevin, Frederic Chiroleu, Emmanuel Jouen, Patrick A D Grimont, Sylvain Brisse, Xavier Nesme, Bui Thi L Ngoc, Pierre Lefeuvre, Christian Verniere
    Abstract:

    We have used amplified fragment length polymorphism (AFLP), multilocus sequence analysis (MLSA) and DNA–DNA hybridization for genotypic classification of Xanthomonas pathovars associated with the plant family Anacardiaceae. AFLP and MLSA results showed congruent phylogenetic relationships of the pathovar mangiferaeindicae (responsible for mango bacterial canker) with strains of Xanthomonas axonopodis subgroup 9.5. This subgroup includes X. axonopodis pv. citri (synonym Xanthomonas citri). Similarly, the pathovar anacardii, which causes cashew bacterial spot in Brazil, was included in X. axonopodis subgroup 9.6 (synonym Xanthomonas fuscans). Based on the thermal stability of DNA reassociation, consistent with the AFLP and MLSA data, the two pathovars share a level of similarity consistent with their being members of the same species. The recent proposal to elevate X. axonopodis pv. citri to species level as X. citri is supported by our data. Therefore, the causal agents of mango bacterial canker and cashew bacterial spot should be classified as pathovars of X. citri, namely X. citri pv. mangiferaeindicae (pathotype strain CFBP 1716) and X. citri pv. anacardii (pathotype strain CFBP 2913), respectively. Xanthomonas fuscans should be considered to be a later heterotypic synonym of Xanthomonas citri.

  • pathological variations within Xanthomonas campestris pv mangiferaeindicae support its separation into three distinct pathovars that can be distinguished by amplified fragment length polymorphism
    Phytopathology, 2007
    Co-Authors: Nathalie Ahyou, Lionel Gagnevin, Frederic Chiroleu, Emmanuel Jouen, Rodrigues J Neto, Olivier Pruvost
    Abstract:

    ABSTRACT Bacterial black spot, caused by Xanthomonas campestris pv. mangiferaeindicae, is an important disease of mango (Mangifera indica). Several other plant genera of the family Anacardiaceae were described as host species for xanthomonads. We studied pathological variations among strains in a worldwide collection from several Anacardiaceae genera. Strains were classified into three pathogenicity groups. Group I strains (from the Old World) multiplied markedly in leaf tissue of mango and cashew (Anacardium occidentale). Group II strains (from Brazil) multiplied markedly in cashew leaf tissue, but not in mango. Moreover, mango leaves inoculated with group I and group II strains exhibited lesions with different morphologies, consistent with variations in symptomology previously reported on mango under field conditions. Group I strains produced black, raised lesions, consistent with the original description of the pathovar, whereas group II strains produced brownish, flat lesions. Group III strains produc...

  • Assessment of genomic variability in Xanthomonas campestris pv. mangiferae-indicae, causal agent of mango black spot.
    1993
    Co-Authors: Lionel Gagnevin
    Abstract:

    Xanthomonas campestris pv. mangiferaeindicae, agent causal de la maladie des tâches noires de la mangue est la principale menace de cette culture. La structure des populations et la variabilite genetique des souches de Xanthomonas campestris pv. mangiferaeindicae ont ete etudiees dans ce travail. Les experiences ont consiste a cloner un fragment a partir d'une banque genomique partielle de Xanthomonas campestris pv. mangiferaeindicae et utiliser les clones comme sondes pour analyse RFLP entre les differentes souches. Les resultats ont montre que toutes les souches testees se groupent de facon compatible avec leur phenotype ou leur hote d'origine, quelle que soit la sonde utilisee. Cela suggere que les souches du pathovar sont genetiquement dissemblables et que la classification de certaines d'entre elles dans le pathovar devrait etre reconsideree. L'idee est confirmee selon laquelle la classification du genre Xanthomonas en pathovars ne reflete pas les relations entre souches, et que des caracteres genotypiques ou phenotypiques autres que le spectre d'hote sont plus appropries pour evaluer la variabilite au sein d'un pathovar

Ulla Bonas - One of the best experts on this subject based on the ideXlab platform.

  • Xanthomonas avrbs3 family type iii effectors discovery and function
    Annual Review of Phytopathology, 2010
    Co-Authors: Jens Boch, Ulla Bonas
    Abstract:

    Xanthomonads are bacterial plant pathogens that cause diseases on many plant species, including important crops. Key to pathogenicity of most Xanthomonas pathovars is a Hrp-type III secretion (T3S) system that translocates effector proteins into plant cells. Within the eukaryotic cell, the effectors are thought to perform a variety of tasks to support bacterial virulence, proliferation, and dissemination. We are only beginning to understand the host targets of different effectors. The largest effector family found in Xanthomonas spp. is the AvrBs3/PthA or TAL (transcription activator-like) family. TAL effectors act as transcriptional activators in the plant cell nucleus. Specificity of TAL effectors is determined by a novel modular DNA-binding domain. Here, we describe the discovery of TAL effectors and their structure, activity, and host targets.

  • how Xanthomonas type iii effectors manipulate the host plant
    Current Opinion in Microbiology, 2009
    Co-Authors: Ulla Bonas
    Abstract:

    Pathogenicity of Xanthomonas and most other Gram-negative phytopathogenic bacteria depends on a conserved type III secretion (T3S) system which injects more than 25 different effector proteins into the plant cell. Extensive studies in the last years on the molecular mechanisms of type III effector function revealed that effector proteins with enzymatic functions seem to play important roles in the interaction of Xanthomonas with its host plants, for example, the SUMO protease XopD. In addition, xanthomonads express a unique class of type III effectors to pursue another strategy. Effectors of the AvrBs3 family, so far only identified in Xanthomonas spp. and Ralstonia solanacearum, mimic plant transcriptional activators and manipulate the plant transcriptome.

  • hrpxv an arac type regulator activates expression of five of the six loci in the hrp cluster of Xanthomonas campestris pv vesicatoria
    Journal of Bacteriology, 1996
    Co-Authors: Kai Wengelnik, Ulla Bonas
    Abstract:

    hrp genes, basic pathogenicity genes of the pepper and tomato pathogen Xanthomonas campestris pv. vesicatoria, are regulated dependent on environmental conditions. We isolated the hrpXv gene, which was found to be outside the large hrp cluster comprising the six loci hrpA to hrpF. The predicted HrpXv protein is 476 amino acids long and has a molecular mass of 52.5 kDa. HrpX is highly conserved among xanthomonads and is a member of the AraC family of regulatory proteins. An hrpXv insertion mutant has a typical hrp phenotype and no longer allows induction of the five hrp loci hrpB to hrpF in the new hrp induction medium XVM2, indicating that HrpXv is the positive regulator of these loci. An hrpXv mutant could be partially complemented by the related hrpB gene of Burkholderia solanacearum, the protein product of which shows 40 and 58% amino acid identity and similarity, respectively, to HrpXv. The hrpXv gene itself has a low basal level of expression that is enhanced in XVM2. Expression of hrpXv as well as that of the hrpA locus is independent of the hrpXv gene. The transcription start site of hrpXv was mapped. Comparison between the hrpXv promoter and the corresponding region of the hrpXc gene from X. campestris pv. campestris revealed sequence conservation up to position -84. A putative helix-turn-helix motif in the C-terminal region of HrpXv and its possible interaction with a conserved hrp promoter element, the plant-inducible promoter box, are discussed.

Frederic Chiroleu - One of the best experts on this subject based on the ideXlab platform.

  • a mlva genotyping scheme for global surveillance of the citrus pathogen Xanthomonas citri pv citri suggests a worldwide geographical expansion of a single genetic lineage
    PLOS ONE, 2014
    Co-Authors: Olivier Pruvost, Lionel Gagnevin, Maxime Magne, Karine Boyer, Alice Leduc, Christophe Tourterel, Christine Drevet, Virginie Ravigne, Fabien Guerin, Frederic Chiroleu
    Abstract:

    MultiLocus Variable number of tandem repeat Analysis (MLVA) has been extensively used to examine epidemiological and evolutionary issues on monomorphic human pathogenic bacteria, but not on bacterial plant pathogens of agricultural importance albeit such tools would improve our understanding of their epidemiology, as well as of the history of epidemics on a global scale. Xanthomonas citri pv. citri is a quarantine organism in several countries and a major threat for the citrus industry worldwide. We screened the genomes of Xanthomonas citri pv. citri strain IAPAR 306 and of phylogenetically related xanthomonads for tandem repeats. From these in silico data, an optimized MLVA scheme was developed to assess the global diversity of this monomorphic bacterium. Thirty-one minisatellite loci (MLVA-31) were selected to assess the genetic structure of 129 strains representative of the worldwide pathological and genetic diversity of X. citri pv. citri. Based on Discriminant Analysis of Principal Components (DAPC), four pathotype-specific clusters were defined. DAPC cluster 1 comprised strains that were implicated in the major geographical expansion of X. citri pv. citri during the 20th century. A subset of 12 loci (MLVA-12) resolved 89% of the total diversity and matched the genetic structure revealed by MLVA-31. MLVA-12 is proposed for routine epidemiological identification of X. citri pv. citri, whereas MLVA-31 is proposed for phylogenetic and population genetics studies. MLVA-31 represents an opportunity for international X. citri pv. citri genotyping and data sharing. The MLVA-31 data generated in this study was deposited in the Xanthomonas citri genotyping database (http://www.biopred.net/MLVA/). (Resume d'auteur)

  • polyphasic characterization of xanthomonads pathogenic to members of the anacardiaceae and their relatedness to species of Xanthomonas
    International Journal of Systematic and Evolutionary Microbiology, 2009
    Co-Authors: Nathalie Ahyou, Lionel Gagnevin, Frederic Chiroleu, Emmanuel Jouen, Patrick A D Grimont, Sylvain Brisse, Xavier Nesme, Bui Thi L Ngoc, Pierre Lefeuvre, Christian Verniere
    Abstract:

    We have used amplified fragment length polymorphism (AFLP), multilocus sequence analysis (MLSA) and DNA–DNA hybridization for genotypic classification of Xanthomonas pathovars associated with the plant family Anacardiaceae. AFLP and MLSA results showed congruent phylogenetic relationships of the pathovar mangiferaeindicae (responsible for mango bacterial canker) with strains of Xanthomonas axonopodis subgroup 9.5. This subgroup includes X. axonopodis pv. citri (synonym Xanthomonas citri). Similarly, the pathovar anacardii, which causes cashew bacterial spot in Brazil, was included in X. axonopodis subgroup 9.6 (synonym Xanthomonas fuscans). Based on the thermal stability of DNA reassociation, consistent with the AFLP and MLSA data, the two pathovars share a level of similarity consistent with their being members of the same species. The recent proposal to elevate X. axonopodis pv. citri to species level as X. citri is supported by our data. Therefore, the causal agents of mango bacterial canker and cashew bacterial spot should be classified as pathovars of X. citri, namely X. citri pv. mangiferaeindicae (pathotype strain CFBP 1716) and X. citri pv. anacardii (pathotype strain CFBP 2913), respectively. Xanthomonas fuscans should be considered to be a later heterotypic synonym of Xanthomonas citri.

  • pathological variations within Xanthomonas campestris pv mangiferaeindicae support its separation into three distinct pathovars that can be distinguished by amplified fragment length polymorphism
    Phytopathology, 2007
    Co-Authors: Nathalie Ahyou, Lionel Gagnevin, Frederic Chiroleu, Emmanuel Jouen, Rodrigues J Neto, Olivier Pruvost
    Abstract:

    ABSTRACT Bacterial black spot, caused by Xanthomonas campestris pv. mangiferaeindicae, is an important disease of mango (Mangifera indica). Several other plant genera of the family Anacardiaceae were described as host species for xanthomonads. We studied pathological variations among strains in a worldwide collection from several Anacardiaceae genera. Strains were classified into three pathogenicity groups. Group I strains (from the Old World) multiplied markedly in leaf tissue of mango and cashew (Anacardium occidentale). Group II strains (from Brazil) multiplied markedly in cashew leaf tissue, but not in mango. Moreover, mango leaves inoculated with group I and group II strains exhibited lesions with different morphologies, consistent with variations in symptomology previously reported on mango under field conditions. Group I strains produced black, raised lesions, consistent with the original description of the pathovar, whereas group II strains produced brownish, flat lesions. Group III strains produc...

Christian Verniere - One of the best experts on this subject based on the ideXlab platform.

  • crispr elements provide a new framework for the genealogy of the citrus canker pathogen Xanthomonas citri pv citri
    BMC Genomics, 2019
    Co-Authors: Kwanho Jeong, Lionel Gagnevin, Alejandra Munozbodnar, Nathalia Arias Rojas, Lucie Poulin, Luis M Rodriguezr, Christian Verniere
    Abstract:

    Xanthomonads are an important clade of Gram-negative bacteria infecting a plethora of economically important host plants, including citrus. Knowledge about the pathogen’s diversity and population structure are prerequisite for epidemiological surveillance and efficient disease management. Rapidly evolving genetic loci, such as Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR), are of special interest to develop new molecular typing tools. We analyzed CRISPR loci of 56 Xanthomonas citri pv. citri strains of world-wide origin, a regulated pathogen causing Asiatic citrus canker in several regions of the world. With one exception, 23 unique sequences built up the repertoire of spacers, suggesting that this set of strains originated from a common ancestor that already harbored these 23 spacers. One isolate originating from Pakistan contained a string of 14 additional, probably more recently acquired spacers indicating that this genetic lineage has or had until recently the capacity to acquire new spacers. Comparison of CRISPR arrays with previously obtained molecular typing data, such as amplified fragment length polymorphisms (AFLP), variable-number of tandem-repeats (VNTR) and genome-wide single-nucleotide polymorphisms (SNP), demonstrated that these methods reveal similar evolutionary trajectories. Notably, genome analyses allowed to generate a model for CRISPR array evolution in X. citri pv. citri, which provides a new framework for the genealogy of the citrus canker pathogen. CRISPR-based typing will further improve the accuracy of the genetic identification of X. citri pv. citri outbreak strains in molecular epidemiology analyses, especially when used concomitantly with another genotyping method.

  • polyphasic characterization of xanthomonads pathogenic to members of the anacardiaceae and their relatedness to species of Xanthomonas
    International Journal of Systematic and Evolutionary Microbiology, 2009
    Co-Authors: Nathalie Ahyou, Lionel Gagnevin, Frederic Chiroleu, Emmanuel Jouen, Patrick A D Grimont, Sylvain Brisse, Xavier Nesme, Bui Thi L Ngoc, Pierre Lefeuvre, Christian Verniere
    Abstract:

    We have used amplified fragment length polymorphism (AFLP), multilocus sequence analysis (MLSA) and DNA–DNA hybridization for genotypic classification of Xanthomonas pathovars associated with the plant family Anacardiaceae. AFLP and MLSA results showed congruent phylogenetic relationships of the pathovar mangiferaeindicae (responsible for mango bacterial canker) with strains of Xanthomonas axonopodis subgroup 9.5. This subgroup includes X. axonopodis pv. citri (synonym Xanthomonas citri). Similarly, the pathovar anacardii, which causes cashew bacterial spot in Brazil, was included in X. axonopodis subgroup 9.6 (synonym Xanthomonas fuscans). Based on the thermal stability of DNA reassociation, consistent with the AFLP and MLSA data, the two pathovars share a level of similarity consistent with their being members of the same species. The recent proposal to elevate X. axonopodis pv. citri to species level as X. citri is supported by our data. Therefore, the causal agents of mango bacterial canker and cashew bacterial spot should be classified as pathovars of X. citri, namely X. citri pv. mangiferaeindicae (pathotype strain CFBP 1716) and X. citri pv. anacardii (pathotype strain CFBP 2913), respectively. Xanthomonas fuscans should be considered to be a later heterotypic synonym of Xanthomonas citri.

Jens Boch - One of the best experts on this subject based on the ideXlab platform.

  • colonization of rice leaf blades by an african strain of Xanthomonas oryzae pv oryzae depends on a new tal effector that induces the rice nodulin 3 os11n3 gene
    Molecular Plant-microbe Interactions, 2011
    Co-Authors: Yanhua Yu, Ralf Koebnik, Jens Boch, Jana Streubel, Sandrine Balzergue, Antony Champion, Jiaxun Feng, Valerie Verdier, Boris Szurek
    Abstract:

    African strains of Xanthomonas oryzae pv. oryzae contain fewer TAL effectors than Asian strains, and their contribution to pathogenicity is unknown. Systematic mutagenesis of tal genes was used to decipher the contribution of each of the eight TAL effector paralogs to pathogenicity of African X. oryzae pv. oryzae BAI3. A strain mutated in talC was severely affected in the production of disease symptoms. Analysis of growth in planta upon leaf-clip inoculation showed that mutant bacteria multiplied only at the site of inoculation at the apex of the leaf, suggesting a requirement for talC during colonization of vascular tissues. Such tissue-specific effect of a tal mutant is a novel phenotype, which has not yet been characterized in other xanthomonads. Microarray experiments comparing the host response of rice leaves challenged with BAI3R vs. BAI3RΔtalC were performed to identify genes targeted by TalC. A total of 120 upregulated and 21 downregulated genes were identified, among them Os11N3, which is a membe...

  • Xanthomonas avrbs3 family type iii effectors discovery and function
    Annual Review of Phytopathology, 2010
    Co-Authors: Jens Boch, Ulla Bonas
    Abstract:

    Xanthomonads are bacterial plant pathogens that cause diseases on many plant species, including important crops. Key to pathogenicity of most Xanthomonas pathovars is a Hrp-type III secretion (T3S) system that translocates effector proteins into plant cells. Within the eukaryotic cell, the effectors are thought to perform a variety of tasks to support bacterial virulence, proliferation, and dissemination. We are only beginning to understand the host targets of different effectors. The largest effector family found in Xanthomonas spp. is the AvrBs3/PthA or TAL (transcription activator-like) family. TAL effectors act as transcriptional activators in the plant cell nucleus. Specificity of TAL effectors is determined by a novel modular DNA-binding domain. Here, we describe the discovery of TAL effectors and their structure, activity, and host targets.

  • insights into genome plasticity and pathogenicity of the plant pathogenic bacterium Xanthomonas campestris pv vesicatoria revealed by the complete genome sequence
    Journal of Bacteriology, 2005
    Co-Authors: Frank Thieme, Thomas Bekel, Ralf Koebnik, Carolin Berger, Daniela Buttner, Camila Caldana, Lars Gaigalat, Jens Boch, Alexander Goesmann, Oliver Kirchner
    Abstract:

    The gram-negative plant-pathogenic bacterium Xanthomonas campestris pv. vesicatoria is the causative agent of bacterial spot disease in pepper and tomato plants, which leads to economically important yield losses. This pathosystem has become a well-established model for studying bacterial infection strategies. Here, we present the whole-genome sequence of the pepper-pathogenic Xanthomonas campestris pv. vesicatoria strain 85-10, which comprises a 5.17-Mb circular chromosome and four plasmids. The genome has a high G+C content (64.75%) and signatures of extensive genome plasticity. Whole-genome comparisons revealed a gene order similar to both Xanthomonas axonopodis pv. citri and Xanthomonas campestris pv. campestris and a structure completely different from Xanthomonas oryzae pv. oryzae. A total of 548 coding sequences (12.2%) are unique to X. campestris pv. vesicatoria. In addition to a type III secretion system, which is essential for pathogenicity, the genome of strain 85-10 encodes all other types of protein secretion systems described so far in gram-negative bacteria. Remarkably, one of the putative type IV secretion systems encoded on the largest plasmid is similar to the Icm/Dot systems of the human pathogens Legionella pneumophila and Coxiella burnetii. Comparisons with other completely sequenced plant pathogens predicted six novel type III effector proteins and several other virulence factors, including adhesins, cell wall-degrading enzymes, and extracellular polysaccharides.