Skip Navigation


Plant and Cell Physiology Advance Access originally published online on November 6, 2009
Plant and Cell Physiology 2009 50(11):1874-1885; doi:10.1093/pcp/pcp129
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Supplementary Data
Right arrow All Versions of this Article:
50/11/1874    most recent
pcp129v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrowRequest Permissions
Google Scholar
Right arrow Articles by Nishimura, T.
Right arrow Articles by Koshiba, T.
PubMed
Right arrow PubMed Citation
Right arrow Articles by Nishimura, T.
Right arrow Articles by Koshiba, T.
Agricola
Right arrow Articles by Nishimura, T.
Right arrow Articles by Koshiba, T.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

© The Author 2009. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oxfordjournals.org

Differential Downward Stream of Auxin Synthesized at the Tip Has a Key Role in Gravitropic Curvature via TIR1/AFBs-Mediated Auxin Signaling Pathways

Takeshi Nishimura1,*, Hitomi Nakano1, Ken-ichiro Hayashi2, Chiharu Niwa1 and Tomokazu Koshiba1

1Department of Biological Sciences, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji-shi, Tokyo, 192-0397 Japan
2Department of Biochemistry, Okayama University of Science, Okayama-shi, Okayama, 700-0005 Japan

*Corresponding author: E-mail, nisimura-takesi{at}ed.tmu.ac.jp; Tel/Fax, +81-426-77-2565.


  Abstract

Since the early days of Darwin, monocot coleoptiles have been used to investigate indole-3-acetic acid (IAA) production, polar transport and tropisms. Here, using maize coleoptiles, we first showed that polar transport of IAA synthesized at the tip region is regulated by ZmPIN(s). Then, the TIR/AFBs-mediated auxin signaling pathway corresponds to the asymmetric IAA flow after gravi-stimulus, which results in tropic curvature. When [13C1115N2]Trp was applied to coleoptile tips, substantial amounts of the stable isotope were incorporated into IAA at the tip region, and the labeled IAA was transported in a polar manner at approximately 7 mm h–1. Immunohistochemical analyses revealed that ZmPIN1(s) was present in almost all cells. ZmPIN1(s) showed a relatively non-polar distribution at the tip, but a basal cellular localization at lower regions. Application of the IAA transport inhibitors 1-N-naphthylphthalamic acid (NPA) and brefeldin A (BFA) at the very tip region almost completely inhibited IAA movement from the tip. These inhibitors also severely suppressed gravitropic bending. PEO-IAA, an auxin antagonist that binds to TIR1/AFBs, suppressed not only the expression of an auxin-responsive ZmSAUR2 gene, but also gravitropic curvature. Expression of ZmSAUR2 was up-regulated on the lower side and down-regulated on the upper side of the coleoptile elongation zone, corresponding to the asymmetric IAA distribution. These results indicate that the asymmetric downward streams of IAA control the differential growth rate of the cells by attenuating TIR1/AFBs-mediated auxin response genes, including ZmSAUR2, and therefore result in tropic curvature.

Keywords: Coleoptiles - IAA - Maize (Zea mays) - PEO-IAA - ZmPIN1 - ZmSAUR2

Abbreviations: BFA, brefeldin A; BH-IAA, tert-butoxycarbonylaminohexyl-IAA; DAPI, 4',6-diamidino-2-phenylindole; EGTA, ethylene glycol bis (aminoethylether)-tetra-acetic acid; GC-SIM-MS, gas chromatography-selected ion monitoring-mass spectrometry; IgG, Immunoglobulin G; KPB, potassium phosphate buffer; MTSB, microtubule-stabilizing buffer; NPA, 1-N-naphthylphthalamic acid; PEO-IAA, {alpha}-(phenylethyl-2-one)-IAA; PIPES, piperazine-1,4-bis(2-ethanesulfonic acid); Trp, tryptophan; YFP, yellow fluorescent protein.

(Received August 4, 2009; Accepted September 15, 2009)
Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?




Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.