Original Article

Planta

, Volume 236, Issue 5, pp 1419-1431

Deciphering the route of Ralstonia solanacearum colonization in Arabidopsis thaliana roots during a compatible interaction: focus at the plant cell wall

  • Catherine DigonnetAffiliated withUniversité de Toulouse, UPS, UMR 5546, Laboratoire de Recherche en Sciences VégétalesCentre National de la Recherche Scientifique, CNRS, UMR 5546, Laboratoire de Recherche en Sciences Végétales
  • , Yves MartinezAffiliated withCentre National de la Recherche Scientifique, CNRS, Plateforme Imagerie-Microscopie, Fédération de Recherche FR3450
  • , Nicolas DenancéAffiliated withUniversité de Toulouse, UPS, UMR 5546, Laboratoire de Recherche en Sciences VégétalesCentre National de la Recherche Scientifique, CNRS, UMR 5546, Laboratoire de Recherche en Sciences Végétales
  • , Marine ChasserayAffiliated withUniversité de Toulouse, UPS, UMR 5546, Laboratoire de Recherche en Sciences VégétalesCentre National de la Recherche Scientifique, CNRS, UMR 5546, Laboratoire de Recherche en Sciences Végétales
  • , Patrick DabosAffiliated withInstitut National de la Recherche Agronomique, INRA, UMR 441, Laboratoire des Interactions Plantes MicroorganismesCentre National de la Recherche Scientifique, CNRS, UMR 2594, Laboratoire des Interactions Plantes Microorganismes
  • , Philippe RanochaAffiliated withUniversité de Toulouse, UPS, UMR 5546, Laboratoire de Recherche en Sciences VégétalesCentre National de la Recherche Scientifique, CNRS, UMR 5546, Laboratoire de Recherche en Sciences Végétales
  • , Yves MarcoAffiliated withInstitut National de la Recherche Agronomique, INRA, UMR 441, Laboratoire des Interactions Plantes MicroorganismesCentre National de la Recherche Scientifique, CNRS, UMR 2594, Laboratoire des Interactions Plantes Microorganismes
  • , Alain JauneauAffiliated withCentre National de la Recherche Scientifique, CNRS, Plateforme Imagerie-Microscopie, Fédération de Recherche FR3450
  • , Deborah GoffnerAffiliated withUniversité de Toulouse, UPS, UMR 5546, Laboratoire de Recherche en Sciences VégétalesCentre National de la Recherche Scientifique, CNRS, UMR 5546, Laboratoire de Recherche en Sciences Végétales Email author 

Rent the article at a discount

Rent now

* Final gross prices may vary according to local VAT.

Get Access

Abstract

The compatible interaction between the model plant, Arabidopsis thaliana, and the GMI1000 strain of the phytopathogenic bacterium, Ralstonia solanacearum, was investigated in an in vitro pathosystem. We describe the progression of the bacteria in the root from penetration at the root surface to the xylem vessels and the cell type-specific, cell wall-associated modifications that accompanies bacterial colonization. Within 6 days post inoculation, R. solanacearum provoked a rapid plasmolysis of the epidermal, cortical, and endodermal cells, including those not directly in contact with the bacteria. Plasmolysis was accompanied by a global degradation of pectic homogalacturonanes as shown by the loss of JIM7 and JIM5 antibody signal in the cell wall of these cell types. As indicated by immunolabeling with Rsol-I antibodies that specifically recognize R. solanacearum, the bacteria progresses through the root in a highly directed, centripetal manner to the xylem poles, without extensive multiplication in the intercellular spaces along its path. Entry into the vascular cylinder was facilitated by cell collapse of the two pericycle cells located at the xylem poles. Once the bacteria reached the xylem vessels, they multiplied abundantly and moved from vessel to vessel by digesting the pit membrane between adjacent vessels. The degradation of the secondary walls of xylem vessels was not a prerequisite for vessel colonization as LM10 antibodies strongly labeled xylem cell walls, even at very late stages in disease development. Finally, the capacity of R. solanacearum to specifically degrade certain cell wall components and not others could be correlated with the arsenal of cell wall hydrolytic enzymes identified in the bacterial genome.

Keywords

Arabidopsis Cell wall Cytology Plant–pathogen interaction Ralstonia Root