Plants respond to pathogen infection by enhancing the antifungal gene expression of root-associated bacteria

Alexandre Jousset, Laurène Rochat, Arnaud Lanoue, Michael Bonkowski, Christoph Keel, Stefan Scheu

Research output: Contribution to journalArticleAcademicpeer-review


Plant health and fitness widely depend on interactions with soil microorganisms. Some bacteria such as pseudomonads can inhibit pathogens by producing antibiotics, and controlling these bacteria could help improve plant fitness. In the present study, we tested whether plants induce changes in the antifungal activity of root-associated bacteria as a response to root pathogens. We grew barley plants in a split-root system with one side of the root system challenged by the pathogen Pythium ultimum and the other side inoculated with the biocontrol strain Pseudomonas fluorescens CHA0. We used reporter genes to follow the expression of ribosomal RNA indicative of the metabolic state and of the gene phlA, required for production of 2,4-diacetylphloroglucinol, a key component of antifungal activity. Infection increased the expression of the antifungal gene phlA. No contact with the pathogen was required, indicating that barley influenced gene expression by the bacteria in a systemic way. This effect relied on increased exudation of diffusible molecules increasing phlA expression, suggesting that communication with rhizosphere bacteria is part of the pathogen response of plants. Tripartite interactions among plants, pathogens, and bacteria appear as a novel determinant of plant response to root pathogens. © 2011 The American Phytopathological Society.
Original languageEnglish
Pages (from-to)352-358
Number of pages7
JournalMolecular Plant-Microbe Interactions
Issue number3
Publication statusPublished - 1 Mar 2011
Externally publishedYes


  • 2,4 diacetylphloroglucinol
  • 2,4-diacetylphloroglucinol
  • para coumaric acid
  • antifungal agent
  • coumaric acid
  • drug derivative
  • fumaric acid
  • fumaric acid derivative
  • phloroglucinol
  • vanillic acid
  • article
  • bacterial gene
  • barley
  • biological pest control
  • gene expression
  • gene expression regulation
  • genetics
  • growth, development and aging
  • metabolism
  • microbiology
  • parasitology
  • pathogenicity
  • plant disease
  • plant root
  • Pseudomonas fluorescens
  • Pythium
  • rhizosphere
  • RNA gene
  • species difference


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