title: The interaction of Arabidopsis with Piriformospora indica shifts from initial transient stress induced by fungus-released chemical mediators to a mutualistic interaction after physical contact of the two symbionts.
abstract: BACKGROUND
  Piriformospora indica, an endophytic fungus of Sebacinales, colonizes the roots of many plant species including Arabidopsis thaliana. The symbiotic interaction promotes plant performance, growth and resistance/tolerance against abiotic and biotic stress.
  
  
  RESULTS
  We demonstrate that exudated compounds from the fungus activate stress and defense responses in the Arabidopsis roots and shoots before the two partners are in physical contact. They induce stomata closure, stimulate reactive oxygen species (ROS) production, stress-related phytohormone accumulation and activate defense and stress genes in the roots and/or shoots. Once a physical contact is established, the stomata re-open, ROS and phytohormone levels decline, and the number and expression level of defense/stress-related genes decreases.
  
  
  CONCLUSIONS
  We propose that exudated compounds from P. indica induce stress and defense responses in the host. Root colonization results in the down-regulation of defense responses and the activation of genes involved in promoting plant growth, metabolism and performance.
authors: Khabat
authors: K
authors: Vahabi
authors: Irena
authors: I
authors: Sherameti
authors: Madhunita
authors: M
authors: Bakshi
authors: Anna
authors: A
authors: Mrozinska
authors: Anatoli
authors: A
authors: Ludwig
authors: Michael
authors: M
authors: Reichelt
authors: Ralf
authors: R
authors: Oelmüller
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000382:microbiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D001487:Basidiomycota / Q000254:growth & development / Q000502:physiology*; D015536:Down-Regulation / Q000187:drug effects / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant; D006861:Hydrogen Peroxide / Q000378:metabolism; D008954:Models, Biological; D010937:Plant Growth Regulators / Q000494:pharmacology; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics / Q000378:metabolism / Q000382:microbiology; D018520:Plant Shoots / Q000187:drug effects / Q000235:genetics / Q000378:metabolism / Q000382:microbiology; D054046:Plant Stomata / Q000187:drug effects / Q000502:physiology; D036226:Seedlings / Q000187:drug effects / Q000378:metabolism / Q000382:microbiology; D013312:Stress, Physiological / Q000187:drug effects / Q000235:genetics; D013559:Symbiosis / Q000187:drug effects / Q000235:genetics; D059467:Transcriptome / Q000187:drug effects / Q000235:genetics; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics
chemical_list: D029681:Arabidopsis Proteins; D010937:Plant Growth Regulators; D006861:Hydrogen Peroxide