Indole-3-acetic acid in microbial and microorganism-plant signaling

FEMS Microbiol Rev. 2007 Jul;31(4):425-48. doi: 10.1111/j.1574-6976.2007.00072.x. Epub 2007 May 17.


Diverse bacterial species possess the ability to produce the auxin phytohormone indole-3-acetic acid (IAA). Different biosynthesis pathways have been identified and redundancy for IAA biosynthesis is widespread among plant-associated bacteria. Interactions between IAA-producing bacteria and plants lead to diverse outcomes on the plant side, varying from pathogenesis to phyto-stimulation. Reviewing the role of bacterial IAA in different microorganism-plant interactions highlights the fact that bacteria use this phytohormone to interact with plants as part of their colonization strategy, including phyto-stimulation and circumvention of basal plant defense mechanisms. Moreover, several recent reports indicate that IAA can also be a signaling molecule in bacteria and therefore can have a direct effect on bacterial physiology. This review discusses past and recent data, and emerging views on IAA, a well-known phytohormone, as a microbial metabolic and signaling molecule.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Bacteria / genetics
  • Bacteria / growth & development
  • Bacteria / metabolism*
  • Bacteria / pathogenicity*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Gene Expression Regulation, Bacterial
  • Indoleacetic Acids / metabolism*
  • Plant Development*
  • Plant Diseases / microbiology*
  • Plant Growth Regulators / metabolism
  • Plants / metabolism
  • Plants / microbiology
  • Signal Transduction*


  • Bacterial Proteins
  • Indoleacetic Acids
  • Plant Growth Regulators
  • indoleacetic acid