title: Biofilm formation, epiphytic fitness, and canker development in Xanthomonas axonopodis pv. citri.
abstract: The phytopathogenic bacterium Xanthomonas axonopodis pv. citri is responsible for the canker disease affecting citrus plants throughout the world. Here, we have evaluated the role of bacterial attachment and biofilm formation in leaf colonization during canker development on lemon leaves. Crystal violet staining and confocal laser scanning microscopy analysis of X. axonopodis pv. citri strains expressing the green fluorescent protein were used to evaluate attachment and biofilm formation on abiotic and biotic (leaf) surfaces. Wild-type X. axonopodis pv. citri attached to and formed a complex, structured biofilm on glass in minimal medium containing glucose. Similar attachment and structured biofilm formation also were seen on lemon leaves. An X. axonopodis pv. citri gumB mutant strain, defective in production of the extracellular polysaccharide xanthan, did not form a structured biofilm on either abiotic or biotic surfaces. In addition, the X. axonopodis pv. citri gumB showed reduced growth and survival on leaf surfaces and reduced disease symptoms. These findings suggest an important role for formation of biofilms in the epiphytic survival of X. axonopodis pv. citri prior to development of canker disease.
authors.affiliation: Fundación Pablo Cassará, Centro de Ciencia y Tecnología Dr. Cesar Milstein, Saladillo 2468 C1440FFX, Ciudad de Buenos Aires, Argentina.
authors.forename: Luciano A
authors.initials: LA
authors.lastname: Rigano
authors.forename: Florencia
authors.initials: F
authors.lastname: Siciliano
authors.forename: Ramón
authors.initials: R
authors.lastname: Enrique
authors.forename: Lorena
authors.initials: L
authors.lastname: Sendín
authors.forename: Paula
authors.initials: P
authors.lastname: Filippone
authors.forename: Pablo S
authors.initials: PS
authors.lastname: Torres
authors.forename: Julia
authors.initials: J
authors.lastname: Qüesta
authors.forename: J Maxwell
authors.initials: JM
authors.lastname: Dow
authors.forename: Atilio P
authors.initials: AP
authors.lastname: Castagnaro
authors.forename: Adrián A
authors.initials: AA
authors.lastname: Vojnov
authors.forename: María Rosa
authors.initials: MR
authors.lastname: Marano
mesh_terms: D001422:Bacterial Adhesion; D018441:Biofilms; D002957:Citrus / Q000378:metabolism / Q000382:microbiology*; D010935:Plant Diseases / Q000382:microbiology*; D018515:Plant Leaves / Q000382:microbiology; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis; D014774:Virulence; D053532:Xanthomonas axonopodis / Q000235:genetics / Q000472:pathogenicity* / Q000502:physiology*
chemical_list: D011135:Polysaccharides, Bacterial; C002563:xanthan gum