Trichoderma virens, a plant beneficial fungus, enhances biomass production and promotes lateral root growth through an auxin-dependent mechanism in Arabidopsis

Plant Physiol. 2009 Mar;149(3):1579-92. doi: 10.1104/pp.108.130369. Epub 2009 Jan 28.


Trichoderma species belong to a class of free-living fungi beneficial to plants that are common in the rhizosphere. We investigated the role of auxin in regulating the growth and development of Arabidopsis (Arabidopsis thaliana) seedlings in response to inoculation with Trichoderma virens and Trichoderma atroviride by developing a plant-fungus interaction system. Wild-type Arabidopsis seedlings inoculated with either T. virens or T. atroviride showed characteristic auxin-related phenotypes, including increased biomass production and stimulated lateral root development. Mutations in genes involved in auxin transport or signaling, AUX1, BIG, EIR1, and AXR1, were found to reduce the growth-promoting and root developmental effects of T. virens inoculation. When grown under axenic conditions, T. virens produced the auxin-related compounds indole-3-acetic acid, indole-3-acetaldehyde, and indole-3-ethanol. A comparative analysis of all three indolic compounds provided detailed information about the structure-activity relationship based on their efficacy at modulating root system architecture, activation of auxin-regulated gene expression, and rescue of the root hair-defective phenotype of the rhd6 auxin response Arabidopsis mutant. Our results highlight the important role of auxin signaling for plant growth promotion by T. virens.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / drug effects
  • Arabidopsis / genetics
  • Arabidopsis / growth & development*
  • Arabidopsis / microbiology*
  • Arabidopsis Proteins / metabolism
  • Basic Helix-Loop-Helix Transcription Factors / metabolism
  • Biomass*
  • Gene Expression Regulation, Plant / drug effects
  • Indoleacetic Acids / chemistry
  • Indoleacetic Acids / metabolism*
  • Indoleacetic Acids / pharmacology
  • Indoles / chemistry
  • Indoles / metabolism
  • Indoles / pharmacology
  • Models, Biological
  • Mutation / genetics
  • Phenotype
  • Plant Roots / anatomy & histology
  • Plant Roots / genetics
  • Plant Roots / growth & development*
  • Plant Roots / microbiology*
  • Protein Processing, Post-Translational / drug effects
  • Recombinant Fusion Proteins / metabolism
  • Seedlings / cytology
  • Seedlings / drug effects
  • Seedlings / growth & development
  • Seedlings / microbiology
  • Trichoderma / physiology*


  • Arabidopsis Proteins
  • Basic Helix-Loop-Helix Transcription Factors
  • Indoleacetic Acids
  • Indoles
  • RHD6 protein, Arabidopsis
  • Recombinant Fusion Proteins
  • indole-3-acetaldehyde
  • tryptophol
  • indoleacetic acid