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TALE1 from Xanthomonas axonopodis pv. manihotis acts as a transcriptional activator in plant cells and is important for pathogenicity in cassava plants

Authors

  • Luisa F. Castiblanco,

    1. Departamento de Ciencias Biológicas, Laboratorio de Micología y Fitopatología, Universidad de Los Andes, Bogota, D.C., Colombia
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    • Present address: Department of Plant Pathology, Michigan State University, East Lansing, MI 48824, USA.
  • Juliana Gil,

    1. Laboratorio de Fitopatología Molecular, Universidad Nacional de Colombia, Bogota, D.C., Colombia
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  • Alejandro Rojas,

    1. Departamento de Ciencias Biológicas, Laboratorio de Micología y Fitopatología, Universidad de Los Andes, Bogota, D.C., Colombia
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    • Present address: Department of Plant Pathology, Michigan State University, East Lansing, MI 48824, USA.
  • Daniela Osorio,

    1. Departamento de Ciencias Biológicas, Laboratorio de Micología y Fitopatología, Universidad de Los Andes, Bogota, D.C., Colombia
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  • Sonia Gutiérrez,

    1. Departamento de Ciencias Biológicas, Laboratorio de Micología y Fitopatología, Universidad de Los Andes, Bogota, D.C., Colombia
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  • Alejandra Muñoz-Bodnar,

    1. Laboratorio de Fitopatología Molecular, Universidad Nacional de Colombia, Bogota, D.C., Colombia
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  • Alvaro L. Perez-Quintero,

    1. Laboratorio de Fitopatología Molecular, Universidad Nacional de Colombia, Bogota, D.C., Colombia
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  • Ralf Koebnik,

    1. Laboratorio de Fitopatología Molecular, Universidad Nacional de Colombia, Bogota, D.C., Colombia
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  • Boris Szurek,

    1. UMR Résistance des Plantes aux Bioagresseurs, Institut de Recherche pour le Développement, IRD–CIRAD–Université de Montpellier II, Montpellier, Cedex 5, France
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  • Camilo López,

    1. Laboratorio de Fitopatología Molecular, Universidad Nacional de Colombia, Bogota, D.C., Colombia
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  • Silvia Restrepo,

    1. Departamento de Ciencias Biológicas, Laboratorio de Micología y Fitopatología, Universidad de Los Andes, Bogota, D.C., Colombia
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  • Valérie Verdier,

    1. UMR Résistance des Plantes aux Bioagresseurs, Institut de Recherche pour le Développement, IRD–CIRAD–Université de Montpellier II, Montpellier, Cedex 5, France
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    • These authors contributed equally to this work.
  • Adriana J. Bernal

    Corresponding author
    • Departamento de Ciencias Biológicas, Laboratorio de Micología y Fitopatología, Universidad de Los Andes, Bogota, D.C., Colombia
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    • These authors contributed equally to this work.

Correspondence: Email: abernal@uniandes.edu.co

Summary

Many plant-pathogenic bacteria suppress pathogen-associated molecular pattern (PAMP)-triggered immunity by injecting effector proteins into the host cytoplasm during infection through the type III secretion system (TTSS). This type III secretome plays an important role in bacterial pathogenicity in susceptible hosts. Xanthomonas axonopodis pv. manihotis (Xam), the causal agent of cassava bacterial blight, injects several effector proteins into the host cell, including TALE1Xam. This protein is a member of the Transcriptional Activator-Like effector (TALE) protein family, formerly known as the AvrBs3/PthA family. TALE1Xam has 13.5 tandem repeats of 34 amino acids each, as well as two nuclear localization signals and an acidic activation domain at the C-terminus. In this work, we demonstrate the importance of TALE1Xam in the pathogenicity of Xam. We use versions of the gene that lack different domains in the protein in structure–function studies to show that the eukaryotic domains at the 3′ end are critical for pathogenicity. In addition, we demonstrate that, similar to the characterized TALE proteins from other Xanthomonas species, TALE1Xam acts as a transcriptional activator in plant cells. This is the first report of the identification of a TALE in Xam, and contributes to our understanding of the pathogenicity mechanisms employed by this bacterium to colonize and cause disease in cassava.

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