The main auxin biosynthesis pathway in Arabidopsis

Kiyoshi Mashiguchi, Keita Tanaka, Tatsuya Sakai, Satoko Sugawara, Hiroshi Kawaide, Masahiro Natsume, Atsushi Hanada, Takashi Yaeno, Ken Shirasu, Hong Yao, Paula McSteen, Yunde Zhao, Ken Ichiro Hayashi, Yuji Kamiya, Hiroyuki Kasahara

Research output: Contribution to journalArticlepeer-review

650 Citations (Scopus)


The phytohormone auxin plays critical roles in the regulation of plant growth and development. Indole-3-acetic acid (IAA) has been recognized as the major auxin for more than 70 y. Although several pathways have been proposed, how auxin is synthesized in plants is still unclear. Previous genetic and enzymatic studies demonstrated that both TRYPTOPHAN AMINOTRANSFERASE OF ARABIDOPSIS (TAA) and YUCCA (YUC) flavin monooxygenase-like proteins are required for biosynthesis of IAA during plant development, but these enzymes were placed in two independent pathways. In this article, we demonstrate that the TAA family produces indole-3-pyruvic acid (IPA) and the YUC family functions in the conversion of IPA to IAA in Arabidopsis (Arabidopsis thaliana) by a quantification method of IPA using liquid chromatography-electrospray ionization-tandem MS. We further show that YUC protein expressed in Escherichia coli directly converts IPA to IAA. Indole-3-acetaldehyde is probably not a precursor of IAA in the IPA pathway. Our results indicate that YUC proteins catalyze a rate-limiting step of the IPA pathway, which is the main IAA biosynthesis pathway in Arabidopsis.

Original languageEnglish
Pages (from-to)18512-18517
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number45
Publication statusPublished - 2011 Nov 8
Externally publishedYes


  • Metabolism
  • Plant hormone

ASJC Scopus subject areas

  • General


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