The Experts below are selected from a list of 144 Experts worldwide ranked by ideXlab platform

Céline Lavire - One of the best experts on this subject based on the ideXlab platform.

  • development of a dna based real time pcr assay to quantify Allorhizobium vitis over time in grapevine vitis vinifera l plantlets
    2021
    Co-Authors: Trong Nguyenhuu, Céline Lavire, Ludovic Vial, Jeanne Dore, Essaid Ait Barka, Christophe Clement, Lisa Sanchez
    Abstract:

    Allorhizobium vitis is the primary causal pathogen of grapevine crown gall disease. Because this endophytic bacterium can survive as a systemic latent (symptomless) infection in grapevine, detecting and monitoring its development in planta is of great importance. In plant bacteria studies, plate counting is routinely used as a simple and reliable method to evaluate the bacterial population level in planta. However, isolation techniques are time-consuming and present some disadvantages such as the risk of contamination and the need for fresh samples for research. In this study, we developed a DNA-based real-time PCR assay that can replace the classical method to monitor the development of Allorhizobium vitis in grapevine plantlets. Primers targeting Allorhizobium vitis chromosomic genes and the virulent tumor-inducing plasmid were validated. The proposed quantitative real-time PCR technique is highly reliable and reproducible to assess Allorhizobium vitis numeration at the earliest stage of infection until tumor development in grapevine plantlets. Moreover, this low-cost technique provides rapid and robust in planta quantification of the pathogen and is suitable for fundamental research to monitor bacterial development over time.

  • Development of a DNA based real time PCR assay to quantify Allorhizobium vitis over time in grapevine ( Vitis vinifera L.) plantlets
    2020
    Co-Authors: Trong Huu Nguyen, Céline Lavire, Ludovic Vial, Jeanne Dore, Christophe Clement, Essaid Ait Barka, Lisa Sanchez
    Abstract:

    Allorhizobium vitis is the primary causal pathogen of grapevine crown gall disease. As this endophytic bacterium can survive as systemic latent (symptomless) infections in grapevine, there is a great importance to detect and monitor its development in planta. In plant-bacteria studies, plate counting is routinely used as a simple and reliable method to evaluate the level of bacterial populations in planta. However, isolation techniques present some disadvantages such as necessity of working on fresh samples, time-consuming and risk of contamination. In this study, we developed a DNA-based real-time PCR assay that can replace the classical method to monitor the development of A. vitis in grapevine plantlets. Primers targeting A. vitis chromosomic genes and the virulent Ti plasmid were validated. The proposed qPCR technique is highly reliable and reproducible to assess A. vitis numeration at the earliest stage of infection until tumor development in grapevine plantlets. Moreover, this is a low-cost technique which provides rapid and robust in planta quantification of the pathogen, suitable for fundamental research to monitor bacterial development over time.

  • characterization and phylogenetic diversity of Allorhizobium vitis isolated from grapevine in morocco
    2020
    Co-Authors: Céline Lavire, David Chapulliot, K. Habbadi, Q. Duplay, Isabelle Kerzaon, R. Benkirane, A. Benbouazza, Florence Wisniewskidye, E.h. Achbani
    Abstract:

    AIMS: Crown gall, a phytobacteriosis characterized by the formation of tumours on plant roots was observed in recently planted vineyards of the Meknes region (Morocco). The objective of this research was to analyse the diversity of pathogenic agrobacteria isolated from grapevine in Morocco. METHODS AND RESULTS: Eighty‐two isolates from 11 affected vineyards were characterized by recA sequencing and were found to belong to Agrobacterium tumefaciens genomospecies G1, G4 or G7, Rhizobium rhizogenes, and to Allorhizobium vitis. Only the All. vitis isolates appeared to be pathogenic on tomato and multilocus sequence analysis phylogenetic analyses revealed a weak genetic diversity, with the definition of only four genomic groups. Definition of the All. vitis genomic groups correlated with specific pathogenic traits: indeed, genomic groups differed with respect to the severity of hypersensitive response symptoms on tobacco leaves, the intensity of necrotic response on grapevine explants and opine profiles. Both vitopine and octopine were detected by UHPLC in tumours induced by isolates of three genomic groups, an opine signature scarcely ever reported. CONCLUSIONS: Allorhizobium vitis is the only causative agent of crown gall on grape in Morocco, pathogenic isolates can be separated into four genomic groups. SIGNIFICANCE AND IMPACT OF THE STUDY: This study of recently crown‐gall‐infested vineyards demonstrated that All. vitis is the only causative agent and revealed the presence of nonpathogenic Agrobacterium strain within tumours. Moreover, as the genetic diversity of the All. vitis isolates is relatively narrow, this study lays the basis for further analyses on the evolution of the disease, on the dissemination of the pTi and more globally on the fate of the different genomic groups in this newly colonized environment.

  • Characterization and phylogenetic diversity of Allorhizobium vitis isolated from grapevine in Morocco
    2019
    Co-Authors: K. Habbadi, Céline Lavire, David Chapulliot, Q. Duplay, Isabelle Kerzaon, R. Benkirane, A. Benbouazza, Florence Wisniewski-dyé, E.h. Achbani, Ludovic Vial
    Abstract:

    AIMS: Crown gall, a phytobacteriosis characterized by the formation of tumours on plant roots was observed in recently planted vineyards of the Meknes region (Morocco). The objective of this research was to analyze the diversity of pathogenic agrobacteria isolated from grapevine in Morocco. METHODS AND RESULTS: Eighty-two isolates from 11 affected vineyards were characterized by recA sequencing and were found to belong to A. tumefaciens genomospecies G1, G4 or G7, Rhizobium rhizogenes, and to Allorhizobium vitis. Only the A. vitis isolates appeared to be pathogenic on tomato and MLSA phylogenetic analyses revealed a weak genetic diversity, with the definition of only four genomic groups. Definition of the A. vitis genomic groups correlateds with specific pathogenic traits: indeed, genomic groups differed with respect to the severity of hypersensitive response symptoms on tobacco leaves, the intensity of necrotic response on grapevine explants, and opine profiles. Both vitopine and octopine were detected by UHPLC in tumors induced by isolates of three genomic groups, an opine signature scarcely ever reported. CONCLUSIONS: Allorhizobium vitis is the only causative agent of crown gall on grape in Morocco, pathogenic isolates can be separated into four genomic groups. SIGNIFICANCE AND IMPACT OF THE STUDY: This study of recently crown-gall-infested vineyards demonstrated that Allorhizobium vitis is the only causative agent and revealed the presence of non-pathogenic Agrobacterium strain within tumors. Moreover, as the genetic diversity of the A. vitis isolates is relatively narrow, this study lays the basis for further analyses on the evolution of the disease, on the dissemination of the pTi and more globally on the fate of the different genomic groups in this newly colonized environment.

  • Essential oils of Origanum compactum and Thymus vulgaris exert a protective effect against the phytopathogen Allorhizobium vitis
    2017
    Co-Authors: K. Habbadi, Ludovic Vial, Isabelle Kerzaon, R. Benkirane, A. Benbouazza, E.h. Achbani, Thibault Meyer, Vincent Gaillard, Céline Lavire
    Abstract:

    Allorhizobium (Agrobacterium) vitis is a host-specific pathogenic bacterium that causes grapevine crown gall disease, affecting vine growth and production worldwide. The antibacterial activities of different aromatic plant essential oils were tested in vitro and in planta against A. vitis. Among the essential oils tested, those of Origanum compactum and Thymus vulgaris showed the most significant in vitro antibacterial activities, with a MIC of 0.156 and 0.312 mg/mL, respectively. A synergistic effect of these two essential oils (1:1) was observed and confirmed by the checkerboard test. Carvacrol (61.8%) and thymol (47.8%) are, respectively, the major compounds in the essential oils of O. compactum and T. vulgaris and they have been shown to be largely responsible for the antibacterial activities of their corresponding essential oils. Results obtained in vitro were reinforced by an in planta pathogenicity test. A mixture of O. compactum and T. vulgaris essential oils (1:1), inoculated into the injured stem of a tomato plant and a grapevine at 0.312 mg/mL as a preventive treatment, reduced both the number of plants developing gall symptoms and the size of the tumors.

Ludovic Vial - One of the best experts on this subject based on the ideXlab platform.

  • development of a dna based real time pcr assay to quantify Allorhizobium vitis over time in grapevine vitis vinifera l plantlets
    2021
    Co-Authors: Trong Nguyenhuu, Céline Lavire, Ludovic Vial, Jeanne Dore, Essaid Ait Barka, Christophe Clement, Lisa Sanchez
    Abstract:

    Allorhizobium vitis is the primary causal pathogen of grapevine crown gall disease. Because this endophytic bacterium can survive as a systemic latent (symptomless) infection in grapevine, detecting and monitoring its development in planta is of great importance. In plant bacteria studies, plate counting is routinely used as a simple and reliable method to evaluate the bacterial population level in planta. However, isolation techniques are time-consuming and present some disadvantages such as the risk of contamination and the need for fresh samples for research. In this study, we developed a DNA-based real-time PCR assay that can replace the classical method to monitor the development of Allorhizobium vitis in grapevine plantlets. Primers targeting Allorhizobium vitis chromosomic genes and the virulent tumor-inducing plasmid were validated. The proposed quantitative real-time PCR technique is highly reliable and reproducible to assess Allorhizobium vitis numeration at the earliest stage of infection until tumor development in grapevine plantlets. Moreover, this low-cost technique provides rapid and robust in planta quantification of the pathogen and is suitable for fundamental research to monitor bacterial development over time.

  • Development of a DNA based real time PCR assay to quantify Allorhizobium vitis over time in grapevine ( Vitis vinifera L.) plantlets
    2020
    Co-Authors: Trong Huu Nguyen, Céline Lavire, Ludovic Vial, Jeanne Dore, Christophe Clement, Essaid Ait Barka, Lisa Sanchez
    Abstract:

    Allorhizobium vitis is the primary causal pathogen of grapevine crown gall disease. As this endophytic bacterium can survive as systemic latent (symptomless) infections in grapevine, there is a great importance to detect and monitor its development in planta. In plant-bacteria studies, plate counting is routinely used as a simple and reliable method to evaluate the level of bacterial populations in planta. However, isolation techniques present some disadvantages such as necessity of working on fresh samples, time-consuming and risk of contamination. In this study, we developed a DNA-based real-time PCR assay that can replace the classical method to monitor the development of A. vitis in grapevine plantlets. Primers targeting A. vitis chromosomic genes and the virulent Ti plasmid were validated. The proposed qPCR technique is highly reliable and reproducible to assess A. vitis numeration at the earliest stage of infection until tumor development in grapevine plantlets. Moreover, this is a low-cost technique which provides rapid and robust in planta quantification of the pathogen, suitable for fundamental research to monitor bacterial development over time.

  • Characterization and phylogenetic diversity of Allorhizobium vitis isolated from grapevine in Morocco
    2019
    Co-Authors: K. Habbadi, Céline Lavire, David Chapulliot, Q. Duplay, Isabelle Kerzaon, R. Benkirane, A. Benbouazza, Florence Wisniewski-dyé, E.h. Achbani, Ludovic Vial
    Abstract:

    AIMS: Crown gall, a phytobacteriosis characterized by the formation of tumours on plant roots was observed in recently planted vineyards of the Meknes region (Morocco). The objective of this research was to analyze the diversity of pathogenic agrobacteria isolated from grapevine in Morocco. METHODS AND RESULTS: Eighty-two isolates from 11 affected vineyards were characterized by recA sequencing and were found to belong to A. tumefaciens genomospecies G1, G4 or G7, Rhizobium rhizogenes, and to Allorhizobium vitis. Only the A. vitis isolates appeared to be pathogenic on tomato and MLSA phylogenetic analyses revealed a weak genetic diversity, with the definition of only four genomic groups. Definition of the A. vitis genomic groups correlateds with specific pathogenic traits: indeed, genomic groups differed with respect to the severity of hypersensitive response symptoms on tobacco leaves, the intensity of necrotic response on grapevine explants, and opine profiles. Both vitopine and octopine were detected by UHPLC in tumors induced by isolates of three genomic groups, an opine signature scarcely ever reported. CONCLUSIONS: Allorhizobium vitis is the only causative agent of crown gall on grape in Morocco, pathogenic isolates can be separated into four genomic groups. SIGNIFICANCE AND IMPACT OF THE STUDY: This study of recently crown-gall-infested vineyards demonstrated that Allorhizobium vitis is the only causative agent and revealed the presence of non-pathogenic Agrobacterium strain within tumors. Moreover, as the genetic diversity of the A. vitis isolates is relatively narrow, this study lays the basis for further analyses on the evolution of the disease, on the dissemination of the pTi and more globally on the fate of the different genomic groups in this newly colonized environment.

  • Essential oils of Origanum compactum and Thymus vulgaris exert a protective effect against the phytopathogen Allorhizobium vitis
    2017
    Co-Authors: K. Habbadi, Ludovic Vial, Isabelle Kerzaon, R. Benkirane, A. Benbouazza, E.h. Achbani, Thibault Meyer, Vincent Gaillard, Céline Lavire
    Abstract:

    Allorhizobium (Agrobacterium) vitis is a host-specific pathogenic bacterium that causes grapevine crown gall disease, affecting vine growth and production worldwide. The antibacterial activities of different aromatic plant essential oils were tested in vitro and in planta against A. vitis. Among the essential oils tested, those of Origanum compactum and Thymus vulgaris showed the most significant in vitro antibacterial activities, with a MIC of 0.156 and 0.312 mg/mL, respectively. A synergistic effect of these two essential oils (1:1) was observed and confirmed by the checkerboard test. Carvacrol (61.8%) and thymol (47.8%) are, respectively, the major compounds in the essential oils of O. compactum and T. vulgaris and they have been shown to be largely responsible for the antibacterial activities of their corresponding essential oils. Results obtained in vitro were reinforced by an in planta pathogenicity test. A mixture of O. compactum and T. vulgaris essential oils (1:1), inoculated into the injured stem of a tomato plant and a grapevine at 0.312 mg/mL as a preventive treatment, reduced both the number of plants developing gall symptoms and the size of the tumors.

  • Phylogeny of the Rhizobium-Allorhizobium-Agrobacterium clade supports the delineation of Neorhizobium gen. nov.
    2014
    Co-Authors: Seyed Abdollah Mousavi, Céline Lavire, Xavier Nesme, Niklas Wahlberg, Ludovic Vial, Lars Paulin, Philippe De Lajudie, Kristina Lindström
    Abstract:

    The genera Agrobacterium, Allorhizobium, and Rhizobium belong to the family Rhizobiaceae. However, the placement of a phytopathogenic group of bacteria, the genus Agrobacterium, among the nitrogen-fixing bacteria and the unclear position of Rhizobium galegae have caused controversy in previous taxonomic studies. To resolve uncertainties in the taxonomy and nomenclature within this family, the phylogenetic relationships of generic members of Rhizobiaceae were studied, but with particular emphasis on the taxa included in Agrobacterium and the "R. galegae complex" (R. galegae and related taxa), using multilocus sequence analysis (MLSA) of six protein-coding housekeeping genes among 114 rhizobial and agrobacterial taxa. The results showed that R. galegae, R. vignae, R. huautlense, and R. alkalisoli formed a separate clade that clearly represented a new genus, for which the name Neorhizobium is proposed. Agrobacterium was shown to represent a separate cluster of mainly pathogenic taxa of the family Rhizobiaceae. A. vitis grouped with Allorhizobium, distinct from Agrobacterium, and should be reclassified as Allorhizobium vitis, whereas Rhizobium rhizogenes was considered to be the proper name for former Agrobacterium rhizogenes. This phylogenetic study further indicated that the taxonomic status of several taxa could be resolved by the creation of more novel genera.

Lisa Sanchez - One of the best experts on this subject based on the ideXlab platform.

  • development of a dna based real time pcr assay to quantify Allorhizobium vitis over time in grapevine vitis vinifera l plantlets
    2021
    Co-Authors: Trong Nguyenhuu, Céline Lavire, Ludovic Vial, Jeanne Dore, Essaid Ait Barka, Christophe Clement, Lisa Sanchez
    Abstract:

    Allorhizobium vitis is the primary causal pathogen of grapevine crown gall disease. Because this endophytic bacterium can survive as a systemic latent (symptomless) infection in grapevine, detecting and monitoring its development in planta is of great importance. In plant bacteria studies, plate counting is routinely used as a simple and reliable method to evaluate the bacterial population level in planta. However, isolation techniques are time-consuming and present some disadvantages such as the risk of contamination and the need for fresh samples for research. In this study, we developed a DNA-based real-time PCR assay that can replace the classical method to monitor the development of Allorhizobium vitis in grapevine plantlets. Primers targeting Allorhizobium vitis chromosomic genes and the virulent tumor-inducing plasmid were validated. The proposed quantitative real-time PCR technique is highly reliable and reproducible to assess Allorhizobium vitis numeration at the earliest stage of infection until tumor development in grapevine plantlets. Moreover, this low-cost technique provides rapid and robust in planta quantification of the pathogen and is suitable for fundamental research to monitor bacterial development over time.

  • Development of a DNA based real time PCR assay to quantify Allorhizobium vitis over time in grapevine ( Vitis vinifera L.) plantlets
    2020
    Co-Authors: Trong Huu Nguyen, Céline Lavire, Ludovic Vial, Jeanne Dore, Christophe Clement, Essaid Ait Barka, Lisa Sanchez
    Abstract:

    Allorhizobium vitis is the primary causal pathogen of grapevine crown gall disease. As this endophytic bacterium can survive as systemic latent (symptomless) infections in grapevine, there is a great importance to detect and monitor its development in planta. In plant-bacteria studies, plate counting is routinely used as a simple and reliable method to evaluate the level of bacterial populations in planta. However, isolation techniques present some disadvantages such as necessity of working on fresh samples, time-consuming and risk of contamination. In this study, we developed a DNA-based real-time PCR assay that can replace the classical method to monitor the development of A. vitis in grapevine plantlets. Primers targeting A. vitis chromosomic genes and the virulent Ti plasmid were validated. The proposed qPCR technique is highly reliable and reproducible to assess A. vitis numeration at the earliest stage of infection until tumor development in grapevine plantlets. Moreover, this is a low-cost technique which provides rapid and robust in planta quantification of the pathogen, suitable for fundamental research to monitor bacterial development over time.

Philippe De Lajudie - One of the best experts on this subject based on the ideXlab platform.

  • Two novel genomospecies in the Agrobacterium tumefaciens species complex associated with rose crown gall
    2019
    Co-Authors: Mafakheri H., Philippe De Lajudie, Taghavi S. M., Pulawska J., Lassalle F., Osdaghi E.
    Abstract:

    In this study, we explored the pathogenicity and phylogenetic position of Agrobacterium spp. strains isolated from crown gall tissues on annual, perennial, and ornamental plants in Iran. Of the 43 strains studied, 10 strains were identified as Allorhizobium vitis (formerly Agrobacterium vitis) using the species-specific primer pair PGF/PGR. Thirty-three remaining strains were studied using multilocus sequence analysis of four housekeeping genes (i.e., atpD, gyrB, recA, and rpoB), from which seven strains were identified as A. larrymoorei and one strain was identified as A. rubi (Rer); the remaining 25 strains were scattered within the A. tumefaciens species complex. Two strains were identified as genomospecies 1 (G1), seven strains were identified as A. radiobacter (G4), seven strains were identified as A. deltaense (G7), two strains were identified as A. nepotum (G14), and one strain was identified as "A. viscosum" (G15). The strains Rnr, Rnw, and Rew as well as the two strains OT33 and R13 all isolated from rose and the strain Ap1 isolated from apple were clustered in three atypical clades within the A. tumefaciens species complex. All but eight strains (i.e., Nec10, Ph38, Ph49, fic9, Fic72, R13, OT33, and Ap1) were pathogenic on tomato and sunflower seedlings in greenhouse conditions, whereas all but three strains (i.e., fic9, Fic72, and OT33) showed tumorigenicity on carrot root discs. The phylogenetic analysis and nucleotide diversity statistics suggested the existence of two novel genomospecies within the A. tumefaciens species complex, which we named "G19" and "G20." Hence, we propose the strains Rew, Rnw, and Rnr as the members of "G19" and the strains R13 and OT33 as the members of G20, whereas the phylogenetic status of the atypical strain Ap1 remains undetermined

  • Revised phylogeny of [i]Rhizobiaceae[/i]: Proposal of the delineation of [i]Pararhizobium gen. nov.[/i], and 13 new species combinations
    2015
    Co-Authors: Seyed Abdollah Mousavi, Anne Willems, Xavier Nesme, Philippe De Lajudie, Kristina Lindström
    Abstract:

    The family Rhizobiaceae accommodates the seven genera Rhizobium, Neorhizobium, Allorhizobium, Agrobacterium, Ensifer (syn. Sinorhizobium), Shinella and Ciceribacter. However, several so-called Rhizobium species do not exhibit robust phylogenetic positions. Rhizobium is extremely heterogeneous and is in need of major revision. Therefore, a phylogenetic examination of the family Rhizobiaceae by multilocus sequence analysis (MLSA) of four housekeeping genes among 100 strains of the family was undertaken. Based on the results we propose the delineation of the new genus Pararhizobium in the Rhizobiaceae family, and 13 new species combinations: Agrobacterium nepotum comb. nov., Agrobacterium pusense comb. nov., Agrobacterium skierniewicense comb. nov., Allorhizobium yids comb. nov., Allorhizobium taibaishanense comb. nov., Allorhizobium paknamense comb. nov., Allorhizobium oryzae comb. nov., Allorhizobium pseudoryzae comb. nov., Allorhizobium borbori comb. nov., Pararhizobium giardinii comb. nov., Pararhizobium capsulatum comb. nov., Pararhizobium herbae comb. nov., and Pararhizobium sphaerophysae comb. nov.

  • Phylogeny of the Rhizobium-Allorhizobium-Agrobacterium clade supports the delineation of Neorhizobium gen. nov.
    2014
    Co-Authors: Seyed Abdollah Mousavi, Céline Lavire, Xavier Nesme, Niklas Wahlberg, Ludovic Vial, Lars Paulin, Philippe De Lajudie, Kristina Lindström
    Abstract:

    The genera Agrobacterium, Allorhizobium, and Rhizobium belong to the family Rhizobiaceae. However, the placement of a phytopathogenic group of bacteria, the genus Agrobacterium, among the nitrogen-fixing bacteria and the unclear position of Rhizobium galegae have caused controversy in previous taxonomic studies. To resolve uncertainties in the taxonomy and nomenclature within this family, the phylogenetic relationships of generic members of Rhizobiaceae were studied, but with particular emphasis on the taxa included in Agrobacterium and the "R. galegae complex" (R. galegae and related taxa), using multilocus sequence analysis (MLSA) of six protein-coding housekeeping genes among 114 rhizobial and agrobacterial taxa. The results showed that R. galegae, R. vignae, R. huautlense, and R. alkalisoli formed a separate clade that clearly represented a new genus, for which the name Neorhizobium is proposed. Agrobacterium was shown to represent a separate cluster of mainly pathogenic taxa of the family Rhizobiaceae. A. vitis grouped with Allorhizobium, distinct from Agrobacterium, and should be reclassified as Allorhizobium vitis, whereas Rhizobium rhizogenes was considered to be the proper name for former Agrobacterium rhizogenes. This phylogenetic study further indicated that the taxonomic status of several taxa could be resolved by the creation of more novel genera.

  • Allorhizobium undicola gen nov sp nov nitrogen fixing bacteria that efficiently nodulate neptunia natans in senegal
    1998
    Co-Authors: Philippe De Lajudie, Anne Willems, Etike Laurentfulele, Urbain Torek, Renata Coopman, Matthew D Collins, Karel Kersters, Bernard Dreyfus, Monique Gillis
    Abstract:

    A group of nodule isolates from Neptunia natans, an indigenous stemnodulated tropical legume found in waterlogged areas of Senegal, was studied. Polyphasic taxonomy was performed, including SDS-PAGE of total proteins, auxanography using API galleries, host-plant specificity, PCR-RFLP of the internal transcribed spacer region between the 16S and the 23S rRNA coding genes, 16S rRNA gene sequencing and DNA-DNA hybridization. It was demonstrated that this group is phenotypically and phylogenetically separate from the known species of Rhizobium, Sinorhizobium, Mesorhizobium, Agrobacterium, Bradyrhizobium and Azorhizobium. Its closest phylogenetic neighbour, as deduced by 16S rRNA gene sequencing, is Agrobacterium vitis (96·2% sequence homology). The name Allorhizobium undicola gen. nov., sp. nov., is proposed for this group of bacteria, which are capable of efficient nitrogen-fixing symbiosis with Neptunia natans, and the type strain is ORS 992T(= LMG 11875T).

  • Allorhizobium undicola gen. nov., sp. nov., nitrogen-fixing bacteria that efficiently nodulate Neptunia natans in Senegal
    1998
    Co-Authors: Philippe De Lajudie, Laurent-fulele E., Willems A., Torck U., Coopman R., Kersters K., Dreyfus Bernard, Gillis M.
    Abstract:

    A group of nodule isolates form #Neptunia natans$, an indigenous stem-nodulated tropical legume found in waterlogged areas of Senegal, was studied. Polyphasic taxonomy was performed, including SDS-PAGE of total proteins, auxanography using API galleries, host-plant specificity, PCR-RFLP of the internal transcribed spacer region between the 16S and the 23S rRNA coding genes, 16S rRNA gene sequencing and DNA-DNA hybridization. It was demonstrated that this group is phenotypically and phylogenetically separate from the known species of #Rhizobium$, Sinorhizobium$, #Mesorhizobium$, #Agrobacterium$, #Bradyrhizobium$, and #Azorhizobium$. Its closest phylogenetic neighbour, as deduced by 16S rRNA gene sequencing, is #Agrobacterium vitis$ (96.2% sequence homology). The name #Allorhizobium undicola$ gen. nov., sp. nov., is proposed for this group of bacteria, which are capable of efficient nitrogen-fixing symbiosis with #Neptunia natans$, and the type strain is ORS 9925T) (= LMG 11875(T)). (Résumé d'auteur

Q. Duplay - One of the best experts on this subject based on the ideXlab platform.

  • characterization and phylogenetic diversity of Allorhizobium vitis isolated from grapevine in morocco
    2020
    Co-Authors: Céline Lavire, David Chapulliot, K. Habbadi, Q. Duplay, Isabelle Kerzaon, R. Benkirane, A. Benbouazza, Florence Wisniewskidye, E.h. Achbani
    Abstract:

    AIMS: Crown gall, a phytobacteriosis characterized by the formation of tumours on plant roots was observed in recently planted vineyards of the Meknes region (Morocco). The objective of this research was to analyse the diversity of pathogenic agrobacteria isolated from grapevine in Morocco. METHODS AND RESULTS: Eighty‐two isolates from 11 affected vineyards were characterized by recA sequencing and were found to belong to Agrobacterium tumefaciens genomospecies G1, G4 or G7, Rhizobium rhizogenes, and to Allorhizobium vitis. Only the All. vitis isolates appeared to be pathogenic on tomato and multilocus sequence analysis phylogenetic analyses revealed a weak genetic diversity, with the definition of only four genomic groups. Definition of the All. vitis genomic groups correlated with specific pathogenic traits: indeed, genomic groups differed with respect to the severity of hypersensitive response symptoms on tobacco leaves, the intensity of necrotic response on grapevine explants and opine profiles. Both vitopine and octopine were detected by UHPLC in tumours induced by isolates of three genomic groups, an opine signature scarcely ever reported. CONCLUSIONS: Allorhizobium vitis is the only causative agent of crown gall on grape in Morocco, pathogenic isolates can be separated into four genomic groups. SIGNIFICANCE AND IMPACT OF THE STUDY: This study of recently crown‐gall‐infested vineyards demonstrated that All. vitis is the only causative agent and revealed the presence of nonpathogenic Agrobacterium strain within tumours. Moreover, as the genetic diversity of the All. vitis isolates is relatively narrow, this study lays the basis for further analyses on the evolution of the disease, on the dissemination of the pTi and more globally on the fate of the different genomic groups in this newly colonized environment.

  • Characterization and phylogenetic diversity of Allorhizobium vitis isolated from grapevine in Morocco
    2019
    Co-Authors: K. Habbadi, Céline Lavire, David Chapulliot, Q. Duplay, Isabelle Kerzaon, R. Benkirane, A. Benbouazza, Florence Wisniewski-dyé, E.h. Achbani, Ludovic Vial
    Abstract:

    AIMS: Crown gall, a phytobacteriosis characterized by the formation of tumours on plant roots was observed in recently planted vineyards of the Meknes region (Morocco). The objective of this research was to analyze the diversity of pathogenic agrobacteria isolated from grapevine in Morocco. METHODS AND RESULTS: Eighty-two isolates from 11 affected vineyards were characterized by recA sequencing and were found to belong to A. tumefaciens genomospecies G1, G4 or G7, Rhizobium rhizogenes, and to Allorhizobium vitis. Only the A. vitis isolates appeared to be pathogenic on tomato and MLSA phylogenetic analyses revealed a weak genetic diversity, with the definition of only four genomic groups. Definition of the A. vitis genomic groups correlateds with specific pathogenic traits: indeed, genomic groups differed with respect to the severity of hypersensitive response symptoms on tobacco leaves, the intensity of necrotic response on grapevine explants, and opine profiles. Both vitopine and octopine were detected by UHPLC in tumors induced by isolates of three genomic groups, an opine signature scarcely ever reported. CONCLUSIONS: Allorhizobium vitis is the only causative agent of crown gall on grape in Morocco, pathogenic isolates can be separated into four genomic groups. SIGNIFICANCE AND IMPACT OF THE STUDY: This study of recently crown-gall-infested vineyards demonstrated that Allorhizobium vitis is the only causative agent and revealed the presence of non-pathogenic Agrobacterium strain within tumors. Moreover, as the genetic diversity of the A. vitis isolates is relatively narrow, this study lays the basis for further analyses on the evolution of the disease, on the dissemination of the pTi and more globally on the fate of the different genomic groups in this newly colonized environment.

  • la galle du collet chez la vigne de la diversite des pathogenes a l etude des plasmides et du quorum sensing d Allorhizobium vitis s4
    2018
    Co-Authors: Q. Duplay
    Abstract:

    La galle du collet, caracterisee par la formation d'une tumeur, represente la bacteriose la plus repandue chez la vigne et entraine d'importantes pertes economiques a travers le monde. L'agent responsable de cette maladie est le plasmide Ti (pTi) qui confere a ces bacteries hotes, telles que des Allorhizobium vitis, leur pouvoir pathogene. En plus du pTi, les A. vitis sont aussi les hotes d'autres plasmides dont les fonctions et les modes de dissemination sont peu documentes. Afin d'etudier l'adaptation particuliere des souches d'A. vitis a la vigne, nous nous sommes interesses a la diversite de ces pathogenes ainsi qu'au role de ces plasmides et a la regulation de leur dissemination. Tout d'abord, nous avons analyse la diversite des isolats provenant de vignobles du Maroc atteints par la galle du collet. Nous avons pu mettre en evidence que l'ensemble des isolats pathogenes (e.g. porteur d'un pTi) forme 4 groupes genetiques se distinguant par le type d'opine produit. Nous nous sommes par la suite interesses a la souche A. vitis S4 qui heberge 5 plasmides dont 3 possedent un mecanisme de transfert pouvant etre regule par un systeme de communication bacterienne nomme quorum sensing (QS). Nous avons montre que le systeme QS du plasmide p130 (renomme pApi) controle non seulement le transfert conjugatif du pApi mais aussi d'autres fonctions plasmidiques non caracterisees. Ce systeme QS necessite la synthese d'une molecule signal de type N-acyl-homoserine lactone qui d'apres nos travaux de caracterisation possede une structure atypique. De plus, des analyses genomiques couplees a des tests de resistance au cuivre nous ont permis d'identifier, sur le plasmide p79 d'A. vitis S4, un ilot de genes potentiellement impliques dans la resistance au cuivre de cette souche. Via des analyses de diversite ainsi que l'etude d'une souche modele, nos travaux fournissent des connaissances sur l'adaptation d'Allorhizobium vitis a son unique plante hote, la vigne