This Article Full Text Full Text (PDF) All Versions of this Article: 14/6/1279    most recent tpc.000653v1 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 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 Web of Science (32) Citing Articles via Google Scholar Google Scholar Articles by Sai, J. Articles by Johnson, C. H. Search for Related Content PubMed PubMed Citation Articles by Sai, J. Articles by Johnson, C. H. Agricola Articles by Sai, J. Articles by Johnson, C. H.

Dark-Stimulated Calcium Ion Fluxes in the Chloroplast Stroma and Cytosol

Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37235

¹ To whom correspondence should be addressed. E-mail carl.h.johnson{at}vanderbilt.edu; fax 615-343-0336

Using transgenic Nicotiana plumbaginifolia seedlings in which the calcium reporter aequorin is targeted to the chloroplast stroma, we found that darkness stimulates a considerable flux of Ca²⁺ into the stroma. This Ca²⁺ flux did not occur immediately after the light-to-dark transition but began 5 min after lights off and increased to a peak at 20 to 30 min after the onset of darkness. Imaging of aequorin emission confirmed that the dark-stimulated luminescence emanated from chloroplast-containing tissues of the seedling. The magnitude of the Ca²⁺ flux was proportional to the duration of light exposure (24 to 120 h) before lights off; the longer the duration of light exposure, the larger the dark-stimulated Ca²⁺ flux. On the other hand, the magnitude of the dark-stimulated Ca²⁺ flux did not appear to vary as a function of circadian time. When seedlings were maintained on a 24-h light/dark cycle, there was a stromal Ca²⁺ burst after lights off every day. Moreover, the waveform of the Ca²⁺ spike was different during long-day versus short-day light/dark cycles. The dark-stimulated Ca²⁺ flux into the chloroplastidic stroma appeared to affect transient changes in cytosolic Ca²⁺ levels. DCMU, an inhibitor of photosynthetic electron transport, caused a significant increase in stromal Ca²⁺ levels in the light but did not affect the magnitude of the dark-stimulated Ca²⁺ flux. This robust Ca²⁺ flux likely plays regulatory roles in the sensing of both light/dark transitions and photoperiod.

This article has been cited by other articles:

				R. Kushwaha, A. Singh, and S. Chattopadhyay Calmodulin7 Plays an Important Role as Transcriptional Regulator in Arabidopsis Seedling Development PLANT CELL, July 1, 2008; 20(7): 1747 - 1759. [Abstract] [Full Text] [PDF]

				Y. Tozawa, A. Nozawa, T. Kanno, T. Narisawa, S. Masuda, K. Kasai, and H. Nanamiya Calcium-activated (p)ppGpp Synthetase in Chloroplasts of Land Plants J. Biol. Chem., December 7, 2007; 282(49): 35536 - 35545. [Abstract] [Full Text] [PDF]

				J. Maple and S. G. Moller Plastid Division: Evolution, Mechanism and Complexity Ann. Bot., April 1, 2007; 99(4): 565 - 579. [Abstract] [Full Text] [PDF]

				C. Aldridge and S. G. Moller The Plastid Division Protein AtMinD1 Is a Ca2+-ATPase Stimulated by AtMinE1 J. Biol. Chem., September 9, 2005; 280(36): 31673 - 31678. [Abstract] [Full Text] [PDF]

				L. Tang, S. Bhat, and M. E. Petracek Light Control of Nuclear Gene mRNA Abundance and Translation in Tobacco Plant Physiology, December 1, 2003; 133(4): 1979 - 1990. [Abstract] [Full Text]

				S. Luan Tyrosine phosphorylation in plant cell signaling PNAS, September 3, 2002; 99(18): 11567 - 11569. [Full Text] [PDF]