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Plant Cell Physiol. 2015 Aug;56(8):1641-54. doi: 10.1093/pcp/pcv088. Epub 2015 Jun 14.

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

Author information

1
RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa, 230-0045 Japan.
2
RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa, 230-0045 Japan United Graduate School of Agricultural Science, Tokyo University of Agriculture & Technology, Tokyo, 183-8509 Japan.
3
Forestry and Forest Products Research Institute, Ibaraki, 305-8687 Japan.
4
Graduate School of Science and Technology, Niigata University, Niigata, 950-2181 Japan.
5
Department of Bioscience and Bioinformatics, Kyushu Institute of Technology, Fukuoka, 820-8502 Japan.
6
Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka, 560-0043 Japan.
7
Section of Cell and Developmental Biology and Howard Hughes Medical Institute, University of California at San Diego, La Jolla, CA 92093-0116, USA.
8
Section of Cell and Developmental Biology, University of California at San Diego, La Jolla, CA 92093-0116, USA.
9
United Graduate School of Agricultural Science, Tokyo University of Agriculture & Technology, Tokyo, 183-8509 Japan.
10
Department of Biochemistry, Okayama University of Science, Okayama, 700-0005 Japan.
11
RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa, 230-0045 Japan Japan Science and Technology Agency (JST), Precursory Research for Embryonic Science and Technology (PRESTO), Saitama, 332-0012 Japan kasahara@riken.jp.

Abstract

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.

KEYWORDS:

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

PMID:
26076971
PMCID:
PMC4523386
DOI:
10.1093/pcp/pcv088
[Indexed for MEDLINE]
Free PMC Article

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