This Article Full Text Full Text (PDF) All Versions of this Article: 137/1/94    most recent pp.104.045427v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via ISI Web of Science (10) Citing Articles via Google Scholar Google Scholar Articles by Xu, J. Articles by Xue, H.-W. Search for Related Content PubMed PubMed Citation Articles by Xu, J. Articles by Xue, H.-W. Agricola Articles by Xu, J. Articles by Xue, H.-W.

CELL BIOLOGY AND SIGNAL TRANSDUCTION

A Role of Arabidopsis Inositol Polyphosphate Kinase, AtIPK2, in Pollen Germination and Root Growth¹

National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Science, Chinese Academy of Sciences, 200032 Shanghai, China (J.X., W.-H.L., Y.W., R.Y., Z.-H.X., H.-W.X.); Partner Group of the Max-Planck-Institute of Molecular Plant Physiology on Plant Molecular Physiology and Signal Transduction, 200032 Shanghai, China (J.X., W.-H.L., Y.W., R.Y., H.-W.X.); School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, United Kingdom (C.A.B.); and University of Potsdam, Institute for Biochemistry and Biology, Department of Molecular Biology, D–14476 Golm, Germany (B.M.-R.)

Inositol polyphosphates, such as inositol trisphosphate, are pivotal intracellular signaling molecules in eukaryotic cells. In higher plants the mechanism for the regulation of the type and the level of these signaling molecules is poorly understood. In this study we investigate the physiological function of an Arabidopsis (Arabidopsis thaliana) gene encoding inositol polyphosphate kinase (AtIPK2), which phosphorylates inositol 1,4,5-trisphosphate successively at the D-6 and D-3 positions, and inositol 1,3,4,5-tetrakisphosphate at D-6, resulting in the generation of inositol 1,3,4,5,6-pentakisphosphate. Semiquantitative reverse transcription-PCR and promoter--glucuronidase reporter gene analyses showed that AtIPK2 is expressed in various tissues, including roots and root hairs, stem, leaf, pollen grains, pollen tubes, the flower stigma, and siliques. Transgenic Arabidopsis plants expressing the AtIPK2 antisense gene under its own promoter were generated. Analysis of several independent transformants exhibiting strong reduction in AtIPK2 transcript levels showed that both pollen germination and pollen tube growth were enhanced in the antisense lines compared to wild-type plants, especially in the presence of nonoptimal low Ca²⁺ concentrations in the culture medium. Furthermore, root growth and root hair development were also stimulated in the antisense lines, in the presence of elevated external Ca²⁺ concentration or upon the addition of EGTA. In addition, seed germination and early seedling growth was stimulated in the antisense lines. These observations suggest a general and important role of AtIPK2, and hence inositol polyphosphate metabolism, in the regulation of plant growth most likely through the regulation of calcium signaling, consistent with the well-known function of inositol trisphosphate in the mobilization of intracellular calcium stores.

Article, publication date, and citation information can be found at www.plantphysiol.org/cgi/doi/10.1104/pp.104.045427.

^* Corresponding author; e-mail.hwxue{at}sibs.ac.cn; fax 86–21–54924060.

Received April 28, 2004; returned for revision September 17, 2004; accepted September 20, 2004.

This article has been cited by other articles:

				Z.-B. Zhang, G. Yang, F. Arana, Z. Chen, Y. Li, and H.-J. Xia Arabidopsis Inositol Polyphosphate 6-/3-Kinase (AtIpk2beta) Is Involved in Axillary Shoot Branching via Auxin Signaling Plant Physiology, June 1, 2007; 144(2): 942 - 951. [Abstract] [Full Text] [PDF]