title: Characterization of a variant of Xanthomonas citri subsp. citri that triggers a host-specific defense response.
abstract: Citrus is an economically important fruit crop that is severely afflicted by Asiatic citrus bacterial canker (CBC), a disease caused by the phytopathogen Xanthomonas citri subsp. citri (X. citri). To gain insight into the molecular epidemiology of CBC, 42 Xanthomonas isolates were collected from a range of Citrus spp. across 17 different orchards in Tucumán, Argentina and subjected to molecular, biochemical, and pathogenicity tests. Analysis of genome-specific X. citri markers and DNA polymorphisms based on repetitive elements-based polymerase chain reaction showed that all 42 isolates belonged to X. citri. Interestingly, pathogenicity tests showed that one isolate, which shares >90% genetic similarity to the reference strain X. citri T, has host range specificity. This new variant of X. citri subsp. citri, named X. citri A(T), which is deficient in xanthan production, induces an atypical, noncankerous chlorotic phenotype in Citrus limon and C. paradisi and weak cankerous lesions in C. aurantifolia and C. clementina leaves. In C. limon, suppression of canker development is concomitant with an oxidative burst; xanthan is not implicated in the phenotype induced by this interaction, suggesting that other bacterial factors would be involved in triggering the defense response.
authors.affiliation: Instituto de Biología Molecular y Celular de Rosario (IBR)–Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Área Virología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 590, S2002LRK Rosario, Argentina.
authors.forename: María A
authors.initials: MA
authors.lastname: Chiesa
authors.forename: María F
authors.initials: MF
authors.lastname: Siciliano
authors.forename: Leonardo
authors.initials: L
authors.lastname: Ornella
authors.forename: Roxana A
authors.initials: RA
authors.lastname: Roeschlin
authors.forename: María A
authors.initials: MA
authors.lastname: Favaro
authors.forename: Natalia Pino
authors.initials: NP
authors.lastname: Delgado
authors.forename: Lorena N
authors.initials: LN
authors.lastname: Sendín
authors.forename: Ingrid G
authors.initials: IG
authors.lastname: Orce
authors.forename: L Daniel
authors.initials: LD
authors.lastname: Ploper
authors.forename: Adrian A
authors.initials: AA
authors.lastname: Vojnov
authors.forename: José Gadea
authors.initials: JG
authors.lastname: Vacas
authors.forename: María P
authors.initials: MP
authors.lastname: Filippone
authors.forename: Atilio P
authors.initials: AP
authors.lastname: Castagnaro
authors.forename: María R
authors.initials: MR
authors.lastname: Marano
mesh_terms: D002957:Citrus / Q000276:immunology* / Q000382:microbiology*; D054884:Host-Pathogen Interactions; D015636:Magnesium Chloride; D010935:Plant Diseases / Q000276:immunology* / Q000382:microbiology*; D018515:Plant Leaves; D011135:Polysaccharides, Bacterial; D014974:Xanthomonas / Q000502:physiology*
chemical_list: D011135:Polysaccharides, Bacterial; D015636:Magnesium Chloride; C002563:xanthan gum