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Multilocus sequence analysis and type III effector repertoire mining provide new insights into the evolutionary history and virulence of Xanthomonas oryzae

Authors

  • AHMED HAJRI,

    1. Département Santé des Plantes et Environnement, Institut National de la Recherche Agronomique (INRA), UMR 077 PaVé, 42 rue Georges Morel, 49071 Beaucouzé cedex, France
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  • CHRYSTELLE BRIN,

    1. Département Santé des Plantes et Environnement, Institut National de la Recherche Agronomique (INRA), UMR 077 PaVé, 42 rue Georges Morel, 49071 Beaucouzé cedex, France
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  • SHUAI ZHAO,

    1. Institut de Recherche pour le Développement, UMR RPB IRD-CIRAD-UM2, 911 Avenue Agropolis BP 64501, 34394 Montpellier Cedex 5, France
    2. State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi 530004, China
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  • PERRINE DAVID,

    1. Département Santé des Plantes et Environnement, Institut National de la Recherche Agronomique (INRA), UMR 077 PaVé, 42 rue Georges Morel, 49071 Beaucouzé cedex, France
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  • JIA-XUN FENG,

    1. State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi 530004, China
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  • RALF KOEBNIK,

    1. Institut de Recherche pour le Développement, UMR RPB IRD-CIRAD-UM2, 911 Avenue Agropolis BP 64501, 34394 Montpellier Cedex 5, France
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  • BORIS SZUREK,

    1. Institut de Recherche pour le Développement, UMR RPB IRD-CIRAD-UM2, 911 Avenue Agropolis BP 64501, 34394 Montpellier Cedex 5, France
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  • VALÉRIE VERDIER,

    1. Institut de Recherche pour le Développement, UMR RPB IRD-CIRAD-UM2, 911 Avenue Agropolis BP 64501, 34394 Montpellier Cedex 5, France
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  • TRISTAN BOUREAU,

    Corresponding author
    1. Département de Biologie, Université d'Angers, UMR 077 PaVé, 42 rue Georges Morel, 49071 Beaucouzé cedex, France
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    • These authors contributed equally to this work.

  • STEPHANE POUSSIER

    Corresponding author
    1. Département de Sciences Biologiques, Agrocampus Ouest—centre d'Angers, Institut National d'Horticulture et de Paysage, UMR 077 PaVé, 42 rue Georges Morel, 49071 Beaucouzé cedex, France
    2. Département de Biologie, Université de la Réunion, UMR C53 PVBMT, 15 avenue René Cassin, BP 7151, 97715 Saint-Denis Cedex 9, La Réunion, France
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    • These authors contributed equally to this work.


Email: stephane.poussier@agrocampus-ouest.fr;

Email: tristan.boureau@univ-angers.fr

SUMMARY

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.

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