OPEN ACCESS ARTICLE

This Article Free via Open Access: OA OA Full Text Full Text (PDF) Supplemental Data OA All Versions of this Article: 147/4/1690    most recent pp.108.123638v1 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 (2) Citing Articles via Google Scholar Google Scholar Articles by Monshausen, G. B. Articles by Gilroy, S. Search for Related Content PubMed PubMed Citation Articles by Monshausen, G. B. Articles by Gilroy, S. Agricola Articles by Monshausen, G. B. Articles by Gilroy, S. Related Collections Membrane Trafficking

Imaging of the Yellow Cameleon 3.6 Indicator Reveals That Elevations in Cytosolic Ca²⁺ Follow Oscillating Increases in Growth in Root Hairs of Arabidopsis^1,[W],[OA]

Department of Botany, University of Wisconsin, Madison, Wisconsin 53706 (G.B.M., S.G.); and BioCurrents Research Center, Marine Biological Laboratory, Woods Hole, Massachusetts 02543 (M.A.M.)

In tip-growing cells, the tip-high Ca²⁺ gradient is thought to regulate the activity of components of the growth machinery, including the cytoskeleton, Ca²⁺-dependent regulatory proteins, and the secretory apparatus. In pollen tubes, both the Ca²⁺ gradient and cell elongation show oscillatory behavior, reinforcing the link between the two. We report that in growing root hairs of Arabidopsis (Arabidopsis thaliana), an oscillating tip-focused Ca²⁺ gradient can be resolved through imaging of a cytosolically expressed Yellow Cameleon 3.6 fluorescence resonance energy transfer-based Ca²⁺ sensor. Both elongation of the root hairs and the associated tip-focused Ca²⁺ gradient show a similar dynamic character, oscillating with a frequency of 2 to 4 min^–1. Cross-correlation analysis indicates that the Ca²⁺ oscillations lag the growth oscillations by 5.3 ± 0.3 s. However, growth never completely stops, even during the slow cycle of an oscillation, and the concomitant tip Ca²⁺ level is always slightly elevated compared with the resting Ca²⁺ concentration along the distal shaft, behind the growing tip. Artificially increasing Ca²⁺ using the Ca²⁺ ionophore A23187 leads to immediate cessation of elongation and thickening of the apical cell wall. In contrast, dissipating the Ca²⁺ gradient using either the Ca²⁺ channel blocker La³⁺ or the Ca²⁺ chelator EGTA is accompanied by an increase in the rate of cell expansion and eventual bursting of the root hair tip. These observations are consistent with a model in which the maximal oscillatory increase in cytosolic Ca²⁺ is triggered by cell expansion associated with tip growth and plays a role in the subsequent restriction of growth.

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: Simon Gilroy (sgilroy{at}wisc.edu).

^[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.108.123638

^* Corresponding author; e-mail sgilroy{at}wisc.edu.

Received May 28, 2008; accepted June 17, 2008; published June 26, 2008.

This article has been cited by other articles:

				A. Y. Cheung and S. C. de Vries Membrane Trafficking: Intracellular Highways and Country Roads Plant Physiology, August 1, 2008; 147(4): 1451 - 1453. [Full Text] [PDF]