Auxin biosynthesis: a simple two-step pathway converts tryptophan to indole-3-acetic acid in plants

Mol Plant. 2012 Mar;5(2):334-8. doi: 10.1093/mp/ssr104. Epub 2011 Dec 8.


Indole-3-acetic acid (IAA), the main naturally occurring auxin, is essential for almost every aspect of plant growth and development. However, only recently have studies finally established the first complete auxin biosynthesis pathway that converts tryptophan (Trp) to IAA in plants. Trp is first converted to indole-3-pyruvate (IPA) by the TAA family of amino transferases and subsequently IAA is produced from IPA by the YUC family of flavin monooxygenases. The two-step conversion of Trp to IAA is the main auxin biosynthesis pathway that plays an essential role in many developmental processes.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Review

MeSH terms

  • Biosynthetic Pathways*
  • Indoleacetic Acids / chemistry
  • Indoleacetic Acids / metabolism*
  • Oxygenases / metabolism
  • Plants / metabolism*
  • Transaminases / metabolism
  • Tryptophan / chemistry
  • Tryptophan / metabolism*


  • Indoleacetic Acids
  • indoleacetic acid
  • Tryptophan
  • Oxygenases
  • Transaminases