This Article Full Text Full Text (PDF) All Versions of this Article: 135/1/587    most recent pp.103.036962v1 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 (7) Citing Articles via Google Scholar Google Scholar Articles by Taybi, T. Articles by Borland, A. M. Search for Related Content PubMed PubMed Citation Articles by Taybi, T. Articles by Borland, A. M. Agricola Articles by Taybi, T. Articles by Borland, A. M.

WHOLE PLANT AND ECOPHYSIOLOGY

Expression of Phosphoenolpyruvate Carboxylase and Phosphoenolpyruvate Carboxylase Kinase Genes. Implications for Genotypic Capacity and Phenotypic Plasticity in the Expression of Crassulacean Acid Metabolism¹

School of Biology, University of Newcastle, Newcastle upon Tyne NE1 7RU, United Kingdom (T.T., A.M.B.); and Plant Science Group, Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom (H.G.N.)

In plants with crassulacean acid metabolism (CAM), dark CO₂ uptake is mediated by phosphoenolpyruvate carboxylase (PEPC), an enzyme that can be regulated at transcriptional and posttranslational levels. Reversible phosphorylation of PEPC is catalyzed by a dedicated PEPC kinase, which in turn is regulated at the transcriptional level over the 24-h cycle in CAM plants. PEPC kinase controls the day/night regulation of PEPC during the CAM cycle, thus facilitating plasticity for optimizing CO₂ uptake under different environmental conditions. To understand the importance of PEPC kinase in relation to its target PEPC in terms of CAM performance, the expression of the genes encoding the two enzymes was investigated in four species of Clusia that have photosynthetic patterns ranging from C₃ photosynthesis to constitutive CAM. By linking changes in the expression of PEPC and PEPC kinase to day/night patterns of leaf gas exchange, organic acid, and soluble sugar contents under different environmental conditions, the genetic and metabolic limitations to CAM plasticity were assessed. The results indicate that PEPC expression is a major factor underpinning the genotypic capacity for CAM and that PEPC kinase expression does not appear to limit CAM. The day/night regulation of Ppck transcript abundance was found to be a consequence of CAM and the day/night cycling of associated metabolites, rather than the primary controlling factor for the temporal separation of carboxylation processes.

Article, publication date, and citation information can be found at www.plantphysiol.org/cgi/doi/10.1104/pp.103.036962.

^* Corresponding author; e-mail tahar.taybi{at}ncl.ac.uk; fax 44–191–222–5228.

Received November 28, 2003; returned for revision February 25, 2004; accepted February 25, 2004.

This article has been cited by other articles:

				K. Winter, M. Garcia, and J. A. M. Holtum Canopy CO2 exchange of two neotropical tree species exhibiting constitutive and facultative CAM photosynthesis, Clusia rosea and Clusia cylindrica J. Exp. Bot., July 1, 2009; 60(11): 3167 - 3177. [Abstract] [Full Text] [PDF]

				J. A. M. Holtum, K. Winter, M. A. Weeks, and T. R. Sexton Crassulacean acid metabolism in the ZZ plant, Zamioculcas zamiifolia (Araceae) Am. J. Botany, October 1, 2007; 94(10): 1670 - 1676. [Abstract] [Full Text] [PDF]