First published online April 13, 2007; 10.1104/pp.106.092163
Plant Physiology 144:942-951 (2007)
© 2007 American Society of Plant Biologists
OPEN ACCESS ARTICLE
CELL BIOLOGY AND SIGNAL TRANSDUCTION
Arabidopsis Inositol Polyphosphate 6-/3-Kinase (AtIpk2 ) Is Involved in Axillary Shoot Branching via Auxin Signaling1,[W],[OA]
Zai-Bao Zhang2,
Guang Yang2,
Fernando Arana,
Zhen Chen,
Yan Li and
Hui-Jun Xia*
Key Laboratory of MOE for Plant Developmental Biology, College of Life Sciences, Wuhan University, Wuhan, Hubei 430072, China (Z.-B.Z., G.Y., Z.C., Y.L., H.-J.X.); and Institute of Biochemistry and Biology, University of Potsdam, Potsdam 14469, Germany (F.A.)
The Arabidopsis (Arabidopsis thaliana) inositol polyphosphate 6-/3-kinase gene (AtIpk2 ) is known to participate in inositol phosphate metabolism. However, little is known about its physiological functions in higher plants. Here, we report that AtIpk2 regulates Arabidopsis axillary shoot branching. By overexpressing AtIpk2 in the wild type and mutants, we found that overexpression of AtIpk2 leads to more axillary shoot branches. Further analysis of AtIpk2 overexpression lines showed that axillary meristem forms earlier and the bud outgrowth rate is also accelerated, resulting in more axillary shoot branches. The AtIpk2 promoter/-glucuronidase (GUS) fusion (AtIpk2::GUS) expression pattern is similar to that of the auxin reporter DR5::GUS. Moreover, AtIpk2 can be induced in response to exogenous indole-3-acetic acid (IAA) treatments. In addition, AtIpk2 overexpression plants exhibit IAA-related phenotypes and are more resistant to exogenous IAA treatments. Further analysis employing reverse transcription-polymerase chain reaction shows that some genes, including auxin-biosynthesis (CYP83B1), auxin-transport (PIN4), and auxin-mediated branching genes (MAX4 and SPS), are regulated by AtIpk2. Taken together, our data provide insights into a role for AtIpk2 in axillary shoot branching through the auxin signaling pathway.
1 This work was supported by the National Natural Science Foundation of China (grant nos. 30570155, 30370142, and 30521004), by the Program for New Century Excellent Talents in University (grant no. NCET–04–0680), by the National Key Project on Plant and Animal Functional Genomics, by the Deutscher Akademischer Austausch Dienst, by the Program for Changjiang Scholars and Innovative Research Team in University (grant no. IRTO437), and by the 111 Project (grant no. B06018).
2 These authors contributed equally to the article.
The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: Hui-Jun Xia (hjxia{at}whu.edu.cn).
[W] The online version of this article contains Web-only data.
[OA] Open Access articles can be viewed online without a subscription.
www.plantphysiol.org/cgi/doi/10.1104/pp.106.092163
* Corresponding author; e-mail hjxia{at}whu.edu.cn; fax 86–27–68752112.
Received November 2, 2006;
accepted March 28, 2007;
published April 13, 2007.
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