RPG acts as a central determinant for infectosome formation and cellular polarization during intracellular rhizobial infections

  1. Beatrice Lace  Is a corresponding author
  2. Chao Su
  3. Daniel Invernot Perez
  4. Marta Rodriguez-Franco
  5. Tatiana Vernié
  6. Morgane Batzenschlager
  7. Sabrina Egli
  8. Cheng-Wu Liu
  9. Thomas Ott  Is a corresponding author
  1. University of Freiburg, Germany
  2. University of Toulouse-Jean Jaurès, France
  3. University of Science and Technology of China, China

Abstract

Host-controlled intracellular accommodation of nitrogen-fixing bacteria is essential for the establishment of a functional Root Nodule Symbiosis (RNS). In many host plants, this occurs via transcellular tubular structures (infection threads - ITs) that extend across cell layers via polar tip-growth. Comparative phylogenomic studies have identified RPG (RHIZOBIUM-DIRECTED POLAR GROWTH) among the critical genetic determinants for bacterial infection. In Medicago truncatula, RPG is required for effective IT progression within root hairs but the cellular and molecular function of the encoded protein remains elusive. Here, we show that RPG resides in the protein complex formed by the core endosymbiotic components VAPYRIN (VPY) and LUMPY INFECTION (LIN) required for IT polar growth, co-localizes with both VPY and LIN in IT tip- and perinuclear-associated puncta of M. truncatula root hairs undergoing infection and is necessary for VPY recruitment into these structures. Fluorescence Lifetime Imaging Microscopy (FLIM) of phosphoinositide species during bacterial infection revealed that functional RPG is required to sustain strong membrane polarization at the advancing tip of the IT. In addition, loss of RPG functionality alters the cytoskeleton-mediated connectivity between the IT tip and the nucleus and affects polar secretion of the cell wall modifying enzyme NODULE PECTATE LYASE (NPL). Our results integrate RPG into a core host machinery required to support symbiont accommodation, suggesting that its occurrence in plant host genomes is essential to co-opt a multimeric protein module committed to endosymbiosis to sustain IT-mediated bacterial infection.

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All data generated or analysed during this study are included in the manuscript and supporting files

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Author details

  1. Beatrice Lace

    Faculty of Biology, Cell Biology, University of Freiburg, Freiburg, Germany
    For correspondence
    beatrice.lace@biologie.uni-freiburg.de
    Competing interests
    The authors declare that no competing interests exist.
  2. Chao Su

    Faculty of Biology, Cell Biology, University of Freiburg, Freiburg, Germany
    Competing interests
    The authors declare that no competing interests exist.
  3. Daniel Invernot Perez

    Faculty of Biology, Cell Biology, University of Freiburg, Freiburg, Germany
    Competing interests
    The authors declare that no competing interests exist.
  4. Marta Rodriguez-Franco

    Faculty of Biology, Cell Biology, University of Freiburg, Freiburg, Germany
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-1183-2075
  5. Tatiana Vernié

    University of Toulouse-Jean Jaurès, Castanet, France
    Competing interests
    The authors declare that no competing interests exist.
  6. Morgane Batzenschlager

    Faculty of Biology, Cell Biology, University of Freiburg, Freiburg, Germany
    Competing interests
    The authors declare that no competing interests exist.
  7. Sabrina Egli

    Faculty of Biology, Cell Biology, University of Freiburg, Freiburg, Germany
    Competing interests
    The authors declare that no competing interests exist.
  8. Cheng-Wu Liu

    Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-6650-6245
  9. Thomas Ott

    Faculty of Biology, Cell Biology, University of Freiburg, Freiburg, Germany
    For correspondence
    Thomas.Ott@biologie.uni-freiburg.de
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-4494-9811

Funding

Bill and Melinda Gates Foundation (OPP1172165)

  • Thomas Ott

Deutsche Forschungsgemeinschaft (431626755)

  • Thomas Ott

Deutsche Forschungsgemeinschaft (39093984)

  • Thomas Ott

Deutsche Forschungsgemeinschaft (414136422)

  • Thomas Ott

Deutsche Forschungsgemeinschaft (426849454)

  • Thomas Ott

China Scholarship Council (201708080016)

  • Chao Su

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Reviewing Editor

  1. Dominique C Bergmann, Stanford University, United States

Version history

  1. Received: June 1, 2022
  2. Preprint posted: June 4, 2022 (view preprint)
  3. Accepted: February 21, 2023
  4. Accepted Manuscript published: March 1, 2023 (version 1)
  5. Version of Record published: March 7, 2023 (version 2)

Copyright

© 2023, Lace et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

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  1. Beatrice Lace
  2. Chao Su
  3. Daniel Invernot Perez
  4. Marta Rodriguez-Franco
  5. Tatiana Vernié
  6. Morgane Batzenschlager
  7. Sabrina Egli
  8. Cheng-Wu Liu
  9. Thomas Ott
(2023)
RPG acts as a central determinant for infectosome formation and cellular polarization during intracellular rhizobial infections
eLife 12:e80741.
https://doi.org/10.7554/eLife.80741

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