Distinct Characteristics of Indole-3-Acetic Acid and Phenylacetic Acid, Two Common Auxins in Plants

Satoko Sugawara, Kiyoshi Mashiguchi, Keita Tanaka, Shojiro Hishiyama, Tatsuya Sakai, Kousuke Hanada, Kaori Kinoshita-Tsujimura, Hong Yu, Xinhua Dai, Yumiko Takebayashi, Noriko Takeda-Kamiya, Tatsuo Kakimoto, Hiroshi Kawaide, Masahiro Natsume, Mark Estelle, Yunde Zhao, Ken Ichiro Hayashi, Yuji Kamiya, Hiroyuki Kasahara

Research output: Contribution to journalArticlepeer-review

86 Citations (Scopus)


The phytohormone auxin plays a central role in many aspects of plant growth and development. IAA is the most studied natural auxin that possesses the property of polar transport in plants. Phenylacetic acid (PAA) has also been recognized as a natural auxin for >40 years, but its role in plant growth and development remains unclear. In this study, we show that IAA and PAA have overlapping regulatory roles but distinct transport characteristics as auxins in plants. PAA is widely distributed in vascular and non-vascular plants. Although the biological activities of PAA are lower than those of IAA, the endogenous levels of PAA are much higher than those of IAA in various plant tissues in Arabidopsis. PAA and IAA can regulate the same set of auxin-responsive genes through the TIR1/AFB pathway in Arabidopsis. IAA actively forms concentration gradients in maize coleoptiles in response to gravitropic stimulation, whereas PAA does not, indicating that PAA is not actively transported in a polar manner. The induction of the YUCCA (YUC) genes increases PAA metabolite levels in Arabidopsis, indicating that YUC flavin-containing monooxygenases may play a role in PAA biosynthesis. Our results provide new insights into the regulation of plant growth and development by different types of auxins.

Original languageEnglish
Pages (from-to)1641-1654
Number of pages14
JournalPlant and Cell Physiology
Issue number8
Publication statusPublished - 2015 Aug 1
Externally publishedYes


  • Auxin transport
  • Indole-3-acetic acid
  • Metabolism
  • Phenylacetic acid
  • Signal transduction

ASJC Scopus subject areas

  • Physiology
  • Plant Science
  • Cell Biology


Dive into the research topics of 'Distinct Characteristics of Indole-3-Acetic Acid and Phenylacetic Acid, Two Common Auxins in Plants'. Together they form a unique fingerprint.

Cite this