Phosphoenolpyruvate carboxykinase in Arabidopsis: Changes in gene expression, protein and activity during vegetative and reproductive development

• Published in: Plant and cell physiology 2007-03, Vol.48 (3), p.441-450
• Main Authors: Malone, S.(University of Sheffield (UK)), Chen, Z.H, Bahrami, A.R, Walker, R.P, Gray, J.E, Leegood, R.C
• Format: Article
• Language: English
• Subjects: Arabidopsis - enzymology; Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis - physiology; ARABIDOPSIS THALIANA; Base Sequence; EXPRESION GENICA; EXPRESSION DES GENES; FLEUR; FLORES; FLOWERS; GENE EXPRESSION; Gene Expression Regulation, Developmental; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; Genes, Plant; In Situ Hybridization; Isoenzymes - genetics; Isoenzymes - metabolism; ORGANE REPRODUCTEUR VEGETAL; ORGANE VEGETATIF DES PLANTES; ORGANOS REPRODUCTORES VEGETALES; ORGANOS VEGETATIVOS DE LAS PLANTAS; Phosphoenolpyruvate Carboxykinase (ATP) - genetics; Phosphoenolpyruvate Carboxykinase (ATP) - metabolism; PLANT REPRODUCTIVE ORGANS; PLANT VEGETATIVE ORGANS; Reproduction - genetics; RNA, Messenger - genetics; RNA, Messenger - metabolism; RNA, Plant - genetics; RNA, Plant - metabolism; SEED; SEMENCE; SEMILLAS
• ISSN: 0032-0781; 1471-9053
• DOI: 10.1093/pcp/pcm014

The aim of this work was to investigate the occurrence of phosphoenolpyruvate carboxykinase (PEPCK) in different tissues of Arabidopsis thaliana throughout its vegetative and reproductive growth. The A. thaliana genome contains two PEPCK genes (PCK1 and PCK2), and these are predicted to generate 73,404 and 72,891 Da protein products, respectively. Both genes were transcribed in a range of tissues; however, PCK1 mRNA appeared to be more abundant and was present in a wider range of tissues. PEPCK protein was present in flowers, fruit, developing seed, germinating seed, leaves, stems and roots. Two PEPCK polypeptides, of -74 and -73 kDa were detected by immunoblotting, and these may arise from PCK1 and PCK2, respectively. PEPCK was abundant in cotyledons during post-germinative growth, and this is consistent with its well established role in gluconeogenesis. PEPCK was also abundant in sink tissues such as young leaves, in developing flowers, fruit and seed. Immunohistochemistry and in situ hybridization showed that PEPCK was present in the nectaries, stigma, endocarp of the fruit wall and in tissues involved in the transfer of assimilates to the developing ovules and seeds, such as the vasculature and seed coat. The potential functions of PEPCK in A. thaliana are discussed.