title: Highly polymorphic markers reveal the establishment of an invasive lineage of the citrus bacterial pathogen Xanthomonas citri pv. citri in its area of origin.
abstract: Investigating the population biology of plant pathogens in their native areas is essential to understand the factors that shape their population structure and favour their spread. Monomorphic pathogens dispatch extremely low genetic diversity in invaded areas, and native areas constitute a major reservoir for future emerging strains. One of these, the gammaproteobacterium Xanthomonas citri pv. citri, causes Asiatic canker and is a considerable threat to citrus worldwide. We studied its population genetic structure by genotyping 555 strains from 12 Vietnam provinces at 14 tandem repeat loci and insertion sequences. Discriminant analysis of principal components identified six clusters. Five of them were composed of endemic strains distributed heterogeneously across sampled provinces. A sixth cluster, VN6, displayed a much lower diversity and a clonal expansion structure, suggesting recent epidemic spread. No differences in aggressiveness on citrus or resistance to bactericides were detected between VN6 and other strains. VN6 likely represents a case of bioinvasion following introduction in a native area likely through contaminated plant propagative material. Highly polymorphic markers are useful for revealing migration patterns of recently introduced populations of a monomorphic bacterial plant pathogen.
authors.affiliation: UMR PVBMT, CIRAD, F-97410, Saint Pierre, La Réunion, France.
authors.forename: Christian
authors.initials: C
authors.lastname: Vernière
authors.forename: Lan
authors.initials: L
authors.lastname: Bui Thi Ngoc
authors.forename: Philippe
authors.initials: P
authors.lastname: Jarne
authors.forename: Virginie
authors.initials: V
authors.lastname: Ravigné
authors.forename: Fabien
authors.initials: F
authors.lastname: Guérin
authors.forename: Lionel
authors.initials: L
authors.lastname: Gagnevin
authors.forename: Nhat
authors.initials: N
authors.lastname: Le Mai
authors.forename: Nguyen M
authors.initials: NM
authors.lastname: Chau
authors.forename: Olivier
authors.initials: O
authors.lastname: Pruvost
mesh_terms: D015373:Bacterial Typing Techniques; D002957:Citrus / Q000382:microbiology*; D005819:Genetic Markers; D014644:Genetic Variation; D005838:Genotype; D058865:Introduced Species; D055029:Inverted Repeat Sequences; D005810:Multigene Family; D010802:Phylogeny; D058974:Phylogeography; D010935:Plant Diseases / Q000382:microbiology; D014744:Vietnam; D014974:Xanthomonas / Q000145:classification* / Q000235:genetics* / Q000378:metabolism
chemical_list: D005819:Genetic Markers