title: From local surveys to global surveillance: three high-throughput genotyping methods for epidemiological monitoring of Xanthomonas citri pv. citri pathotypes.
abstract: Asiatic citrus canker is a major disease worldwide, and its causal agent, Xanthomonas citri pv. citri, is listed as a quarantine organism in many countries. Analysis of the molecular epidemiology of this bacterium is hindered by a lack of molecular typing techniques suitable for surveillance and outbreak investigation. We report a comparative evaluation of three typing techniques, amplified fragment length polymorphism (AFLP) analysis, insertion sequence ligation-mediated PCR (IS-LM-PCR) typing, and multilocus variable-number tandem-repeat analysis (MLVA), with 234 strains originating from Asia, the likely center of origin of the pathogen, and reference strains of pathotypes A, A*, and A(w), which differ in host range. The typing techniques were congruent in describing the diversity of this strain collection, suggesting that the evolution pattern of the bacterium may be clonal. Based on a hierarchical analysis of molecular variance, the AFLP method best described the genetic variation found among pathotypes whereas MLVA best described the variation found among individual strains from the same countries or groups of neighboring countries. IS-LM-PCR data suggested that the transposition of insertion sequences in the genome of X. citri pv. citri occurs rarely enough not to disturb the phylogenetic signal. This technique may be useful for the global surveillance of non-epidemiologically related strains. Although pathological characteristics of strains could be most often predicted from genotyping data, we report the occurrence in the Indian peninsula of strains genetically related to pathotype A* strains but with a host range similar to that of pathotype A, which makes the classification of this bacterium even more complicated.
authors.affiliation: CIRAD, UMR Peuplements Végétaux et Bioagresseurs en Milieu Tropical CIRAD-Université de la Réunion, Pôle de Protection des Plantes, 7 chemin de l'Irat, 97410 Saint Pierre, La Réunion, France.
authors.forename: Thi Ngoc Lan
authors.initials: TN
authors.lastname: Bui
authors.forename: Christian
authors.initials: C
authors.lastname: Vernière
authors.forename: Philippe
authors.initials: P
authors.lastname: Jarne
authors.forename: Sylvain
authors.initials: S
authors.lastname: Brisse
authors.forename: Fabien
authors.initials: F
authors.lastname: Guérin
authors.forename: Sébastien
authors.initials: S
authors.lastname: Boutry
authors.forename: Lionel
authors.initials: L
authors.lastname: Gagnevin
authors.forename: Olivier
authors.initials: O
authors.lastname: Pruvost
mesh_terms: D015373:Bacterial Typing Techniques / Q000379:methods*; D002957:Citrus / Q000382:microbiology; D016000:Cluster Analysis; D016172:DNA Fingerprinting / Q000379:methods*; D004269:DNA, Bacterial / Q000235:genetics; D005838:Genotype; D007194:India; D017720:Molecular Epidemiology / Q000379:methods; D010935:Plant Diseases / Q000382:microbiology*; D014974:Xanthomonas / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification
chemical_list: D004269:DNA, Bacterial