This Article Full Text Full Text (PDF) All Versions of this Article: 138/4/2280    most recent pp.105.061903v1 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 (25) Citing Articles via Google Scholar Google Scholar Articles by Lu, Y. Articles by Sharkey, T. D. Search for Related Content PubMed PubMed Citation Articles by Lu, Y. Articles by Sharkey, T. D. Agricola Articles by Lu, Y. Articles by Sharkey, T. D.

BIOENERGETICS AND PHOTOSYNTHESIS

Daylength and Circadian Effects on Starch Degradation and Maltose Metabolism¹

Department of Botany (Y.L., T.D.S.) and Department of Biochemistry (J.P.G.), University of Wisconsin, Madison, Wisconsin 53706

Transitory starch is stored during the day inside chloroplasts and broken down at night for export. Maltose is the primary form of carbon export from chloroplasts at night. We investigated the influence of daylength and circadian rhythms on starch degradation and maltose metabolism. Starch breakdown was faster in plants of Arabidopsis (Arabidopsis thaliana) ecotype Wassilewskija growing in long days. Transcript levels of genes encoding enzymes involved in starch degradation and maltose metabolism showed a strong diurnal rhythm. Under altered photoperiods, the transcript levels and the rate of starch degradation changed within one day/night cycle. However, the amount of proteins involved in starch degradation was maintained relatively constant throughout the day/night cycle. To investigate whether the diurnal cycling of the transcript levels is only a response to light or is also regulated by a circadian clock, we measured the amount of messenger RNAs in Arabidopsis leaves under continuous light and continuous darkness. The expression of genes encoding starch degradation-related enzymes was under very strong circadian control in continuous light. Under continuous light, the amount of maltose also showed a strong endogenous rhythm close to 24 h, indicating that maltose metabolism is under circadian control. Light is necessary for the cycling of transcript levels and maltose levels. Under continuous darkness, these genes were barely expressed, and no cycling of maltose levels was observed.

Article, publication date, and citation information can be found at www.plantphysiol.org/cgi/doi/10.1104/pp.105.061903.

^* Corresponding author; e-mail tsharkey{at}wisc.edu; fax 608–262–7509.

Received February 24, 2005; returned for revision April 13, 2005; accepted April 20, 2005.

This article has been cited by other articles:

				B. Usadel, O. E. Blasing, Y. Gibon, K. Retzlaff, M. Hohne, M. Gunther, and M. Stitt Global Transcript Levels Respond to Small Changes of the Carbon Status during Progressive Exhaustion of Carbohydrates in Arabidopsis Rosettes Plant Physiology, April 1, 2008; 146(4): 1834 - 1861. [Abstract] [Full Text] [PDF]

				L. Li, H. Ilarslan, M. G. James, A. M. Myers, and E. S. Wurtele Genome wide co-expression among the starch debranching enzyme genes AtISA1, AtISA2, and AtISA3 in Arabidopsis thaliana J. Exp. Bot., September 20, 2007; (2007) erm180v1. [Abstract] [Full Text] [PDF]

				A. K. Grennan Regulation of Starch Metabolism in Arabidopsis Leaves Plant Physiology, December 1, 2006; 142(4): 1343 - 1345. [Full Text] [PDF]

				Y. Lu, J. M. Steichen, J. Yao, and T. D. Sharkey The Role of Cytosolic {alpha}-Glucan Phosphorylase in Maltose Metabolism and the Comparison of Amylomaltase in Arabidopsis and Escherichia coli Plant Physiology, November 1, 2006; 142(3): 878 - 889. [Abstract] [Full Text] [PDF]

				J.-P. Ral, C. Colleoni, F. Wattebled, D. Dauvillee, C. Nempont, P. Deschamps, Z. Li, M. K. Morell, R. Chibbar, S. Purton, et al. Circadian Clock Regulation of Starch Metabolism Establishes GBSSI as a Major Contributor to Amylopectin Synthesis in Chlamydomonas reinhardtii Plant Physiology, September 1, 2006; 142(1): 305 - 317. [Abstract] [Full Text] [PDF]

				S. E. Weise, S. M. Schrader, K. R. Kleinbeck, and T. D. Sharkey Carbon Balance and Circadian Regulation of Hydrolytic and Phosphorolytic Breakdown of Transitory Starch Plant Physiology, July 1, 2006; 141(3): 879 - 886. [Abstract] [Full Text] [PDF]

				O. E. Blasing, Y. Gibon, M. Gunther, M. Hohne, R. Morcuende, D. Osuna, O. Thimm, B. Usadel, W.-R. Scheible, and M. Stitt Sugars and Circadian Regulation Make Major Contributions to the Global Regulation of Diurnal Gene Expression in Arabidopsis PLANT CELL, December 1, 2005; 17(12): 3257 - 3281. [Abstract] [Full Text] [PDF]