title: Multilocus sequence analysis and type III effector repertoire mining provide new insights into the evolutionary history and virulence of Xanthomonas oryzae.
abstract: Multilocus sequence analysis (MLSA) and type III effector (T3E) repertoire mining were performed to gain new insights into the genetic relatedness of Xanthomonas oryzae pv. oryzae (Xoo) and Xanthomonas oryzae pv. oryzicola (Xoc), two major bacterial pathogens of rice. Based on a collection of 45 African and Asian strains, we first sequenced and analysed three housekeeping genes by MLSA, Bayesian clustering and a median-joining network approach. Second, we investigated the distribution of 32 T3E genes, which are known to be major virulence factors of plant pathogenic bacteria, in all selected strains, by polymerase chain reaction and dot-blot hybridization methods. The diversity observed within housekeeping genes, as well as within T3E repertoires, clearly showed that both pathogens belong to closely related, but distinct, phylogenetic groups. Interestingly, these evolutionary groups are differentiated according to the geographical origin of the strains, suggesting that populations of Xoo and Xoc might be endemic in Africa and Asia, and thus have evolved separately. We further revealed that T3E gene repertoires of both pathogens comprise core and variable gene suites that probably have distinct roles in pathogenicity and different evolutionary histories. In this study, we carried out a functional analysis of xopO, a differential T3E gene between Xoo and Xoc, to determine the involvement of this gene in tissue specificity. Altogether, our data contribute to a better understanding of the evolutionary history of Xoo and Xoc in Africa and Asia, and provide clues for functional studies aiming to understand the virulence, host and tissue specificity of both rice pathogens.
authors.affiliation: Département Santé des Plantes et Environnement, Institut National de la Recherche Agronomique, UMR 077 PaVé, 42 rue Georges Morel, 49071 Beaucouzé cedex, France.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Hajri
authors.forename: Chrystelle
authors.initials: C
authors.lastname: Brin
authors.forename: Shuai
authors.initials: S
authors.lastname: Zhao
authors.forename: Perrine
authors.initials: P
authors.lastname: David
authors.forename: Jia-Xun
authors.initials: JX
authors.lastname: Feng
authors.forename: Ralf
authors.initials: R
authors.lastname: Koebnik
authors.forename: Boris
authors.initials: B
authors.lastname: Szurek
authors.forename: Valérie
authors.initials: V
authors.lastname: Verdier
authors.forename: Tristan
authors.initials: T
authors.lastname: Boureau
authors.forename: Stephane
authors.initials: S
authors.lastname: Poussier
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics; D005075:Biological Evolution; D058885:Multilocus Sequence Typing / Q000379:methods*; D012275:Oryza / Q000382:microbiology; D010802:Phylogeny; D014774:Virulence / Q000235:genetics / Q000502:physiology*; D014974:Xanthomonas / Q000145:classification / Q000235:genetics* / Q000472:pathogenicity*
chemical_list: D001426:Bacterial Proteins