Abstract
In cucumber (Cucumis sativus L.), phosphoenolpyruvate carboxykinase (PEPCK) was shown by activity measurements and immunoblots to be present in leaves, stems, roots, flowers, fruit and seed. However, immunolocalisation showed that it was present only in certain cell types. PEPCK was present in the companion cells of the adaxial phloem of minor veins, the adaxial and abaxial phloem of larger veins, the internal and external phloem of vascular bundles in petioles and stems, the phloem in roots and the extra-fascicular phloem in leaves, cotyledons, petioles and stems. Immunohistochemical evidence suggests that both the extra-fascicular phloem and the adaxial phloem are involved in the transport of amino acids. In roots and stems, the abundance of PEPCK was greatly increased by watering plants with a solution of ammonium chloride at low, but not at high pH. PEPCK also increased in leaves, but not roots or stems, of seedlings grown in an atmosphere containing 5% CO2, and in roots and stems of seedlings watered with butyric acid. All these treatments are known to lower the pH of plant cells. Amino acid metabolism in the phloem may produce an excess of carbon skeletons, pH perturbations and an imbalance in the production/utilisation of NADH. This raises the possibility that PEPCK may function in the conversion of these carbon skeletons to PEP, which, depending on the energy requirements of the phloem, is subsequently utilised by either gluconeogenesis or the Krebs cycle, which both consume protons.
Abbreviations
- Asp :
-
Aspartate
- Asn :
-
Asparagine
- Glu :
-
Glutamate
- Gln :
-
Glutamine
- NADP-ME :
-
NADP-malic enzyme
- OAA :
-
Oxaloacetate
- PEP :
-
Phosphoenolpyruvate
- PEPC :
-
Phosphoenolpyruvate carboxylase
- PEPCK :
-
Phosphoenolpyruvate carboxykinase
References
Aoki E, Semba R, Keino H, Kato K, Kashiwamata S (1988) Glycine-like immunoreactivity in the rat auditory pathway. Brain Res 442:63–71
Atkinson DE, Bourke E (1984) The role of ureagenesis in pH homeostasis. Trends Biochem Sci 9:297–300
Borland A, Técsi LI, Leegood RC, Walker RP (1998) Inducibility of Crassulacean acid metabolism (CAM) in Clusia; physiological/biochemical characterisation and intercellular localisation of carboxylation processes in three species which exhibit different degrees of CAM. Planta 205:342–351
Brosnan JT (2000) Glu, at the interface between amino acid and carbohydrate metabolism. J Nutr 130:988S–990S
Chen Z-H, Walker RP, Acheson RM, Técsi LI, Wingler A, Lea PJ, Leegood RC (2000) Are isocitrate lyase and phosphoenolpyruvate carboxykinase involved in gluconeogenesis during senescence of barley leaves and cucumber cotyledons? Plant Cell Physiol 41:960–967
Crafts AS (1932) Phloem anatomy, exudation and transport of organic nutrients in cucurbits. Plant Physiol 7:183–225
Cramer MD, Lewis OAM, Lips SH (1993) Inorganic carbon fixation and metabolism in maize roots is affected by nitrate and ammonium nutrition. Physiol Plant 89:632–639
Croniger CM, Olswang Y, Reshef L, Kalhan SC, Tilghman SM, Hanson RW (2002) Phosphoenolpyruvate carboxykinase revisited: Insights into its metabolic role. Biochem Mol Biol Educ 30:14–20
Dannenhoffer JM, Schulz A, Skaggs MI, Bostwick DE, Thompson GA (1997) Expression of the phloem lectin is developmentally linked to vascular differentiation in curcurbits. Planta 210:405–414
Davies DD (1986) The fine control of cytosolic pH. Physiol Plant 67:702–706
Esau K (1965) Plant anatomy. Wiley, New York, p 271
Esau K (1969) The phloem. In: Zimmermann W, Ozenda P, Wulff HD (eds) Handbuch der Pflanzenanatomie. Borntraeger, Berlin
Evert RF, Eschrich W, Eichhorn SE (1973) P-protein distribution in mature sieve elements of Curcurbita maxima. Planta 109:193–210
Fischer A (1884) Studien über die siebröhren der dicotylenblätter. Ber Verh Kon Sachs Ges Wiss Leipzig Math-Phys C1 37:245–290
Flatt JP (1970) Conversion of carbohydrate to fat in adipose tissue: an energy-yielding and, therefore, self-limiting process. J Lipid Res 11:131–143
Fritz E, Evert RF, Heyser W (1983) Microautoradiographic studies of phloem loading and transport in the leaf of Zea mays L. Planta 159:193–206
Gerendás J, Ratcliffe RG (2000) Intracellular pH regulation in maize root tips exposed to ammonium at high external pH. J Exp Bot 51:207–219
Gerendás J, Ratcliffe RG, Sattelmacher (1990) 31P nuclear magnetic resonance evidence for differences in intracellular pH in the roots of maize seedlings grown with nitrate or ammonium. J Plant Physiol 137:125–128
Hanson RW, Reshef L (1997) Regulation of phosphoenolpyruvate carboxykinase (GTP) gene expression. Annu Rev Biochem 66:581–611
Haritatos E, Keller F, Turgeon R (1996) Raffinose oligosaccharide concentrations measured in individual cell and tissue types in Cucumis melo L. leaves: implications for phloem loading. Planta 198:614–622
Hayashi H, Chino M (1990) Chemical composition of phloem sap from the uppermost internode of the rice plant. Plant Cell Physiol 31:247–251
Hsiang BCH, Bush DR (1992) Stachyose, amino acid and sucrose transport in plasma membrane vesicles isolated from zucchini. Plant Physiol [Suppl] 99:41
Jungas RL, Halperin ML, Brosnan JT (1992) Quantitative analysis of amino acid oxidation and related gluconeogenesis in humans. Physiol Rev 72:419–448
Kim DJ, Smith SM (1994) Molecular cloning of cucumber phosphoenolpyruvate carboxykinase and developmental regulation of gene expression. Plant Mol Biol 26:423–434
Kurkdjian A, Guern J (1989) Intracellular pH: measurement and importance in cell activity. Annu Rev Plant Physiol Plant Mol Biol 40:271–303
Langdale JA, Rothermel BA, Nelson T (1988) Cellular patterns of photosynthetic gene expression in developing maize leaves. Genes Dev 2:105–115
Lea PJ, Chen Z-H, Leegood RC, Walker RP (2001) Does phosphoenolpyruvate carboxykinase have a role in both amino acid and carbohydrate metabolism? Amino Acids 20:225–241
Leegood RC, ap Rees T (1978) Phosphoenolpyruvate carboxykinase and gluconeogenesis in cotyledons of Cucurbita pepo. Biochim Biophys Acta 524:207–218
Leegood RC, Walker RP (1999) Phosphoenolpyruvate carboxykinase in plants: its role and regulation. In: Bryant JA, Burrell MM, Kruger NJ (eds) Plant carbohydrate biochemistry. BIOS, Oxford, pp 201–213
Leegood RC, Walker RP (2003) Regulation and roles of phosphoenolpyruvate carboxykinase in plants. Arch Biochem Biophys 414:204–210
Lindt T, Feller U (1987) Effect of nitrate and ammonium on long distance transport in cucumber plants. Bot Helv 97:45–52
Lohaus G, Burba M, Heldt HW (1994) Comparison of the contents of sucrose and amino acids in the leaves, phloem sap and taproots of high and low sugar-producing hybrids of sugar beet (Beta vulgaris L.). J Exp Bot 45:1097–1101
Ma N, Aoki E, Semba R (1994) An immunohistochemical study of Asp, Glu and taurine in rat kidney. J Histochem Cytochem 42:621–626
Mitchell DE, Gadus MV, Madore MA (1992) Patterns of assimilate production and translocation in muskmelon (Cucumis melo L.). Plant Physiol 99:959–965
Murray DR (1987) Nutritive role of seedcoats in developing legume seeds. Am J Bot 74:1122–1137
Owen OE, Kalhan SC, Hanson RW (2002) The key role of anaplerosis and cataplerosis for citric acid cycle function. J Biol Chem 277:30409–30412
Pate JS (1980) Transport and partitioning of nitrogenous solutes. Annu Rev Plant Physiol 31:313–340
Peterson CA, Currier HB (1969) An investigation of bidirectional translocation in the phloem. Physiol Plant 22:1238–1250
Pogson CI, Longshaw ID, Roobol A, Smith SA, Alleyne GAO (1976) Phosphoenolpyruvate carboxykinase and renal gluconeogenesis. In: Hanson RW, Mehlman MA (eds) Gluconeogenesis: its role in mammalian species. Wiley, New York, pp 335–367
Pristupa NA (1983) Distribution of ketosugars among cells of conducting bundles of the Cucurbita pepo leaf. Fiziol Rast 30:492–498
Raven JA, Smith FA (1976) Nitrogen assimilation and transport in vascular land plants in relation to intracellular pH regulation. New Phytol 76:415–431
Santamaria P, Elia A (1997) Producing nitrate-free endive heads: effect of nitrogen form on growth, yield, and ion composition of endive. J Am Soc Hort Sci 122:140–145
Savchenko G, Wiese C, Neimanis S, Hedrich R, Heber U (2000) pH regulation in apoplastic and cytoplasmic cell compartments of leaves. Planta 211:246–255
Schaffer AA, Pharr DM, Madore M (1996) Cucurbits. In: Zamski E, Schaffer AA (eds) Photoassimilate distribution in plants and crops. Source–sink relationships. Dekker, New York, pp 729–757
Schmitz K, Cuypers B, Moll M (1987) Pathway of assimilate transfer between mesophyll cells and minor veins in leaves of Cucumis melo L. Planta 171:19–29
She P, Shiota M, Shelton KD, Chalkley R, Postic C, Magnuson MA (2000) Phosphoenolpyruvate carboxykinase is necessary for the integration of hepatic energy metabolism. Mol Cell Biol 20:6508–6517
Smith AM, ap Rees T (1979) Pathways of carbohydrate fermentation in the roots of marsh plants. Planta 146:327–334
Smith LM, Sabnis DD, Johnson RPC (1987) Immunocytochemical localisation of phloem lectin from Curcurbita maxima using peroxidase and colloidal-gold labels. Planta 170:461–470
Storm-Mathison J, Leknes AK, Bore AT, Vaaland JL, Edminson P, Haug F-MS, Otterson OP (1983) First visualisation of Glu and GABA in neurones by immunohistochemistry. Nature 301:517–520
Tobin AK, Yamaya T (2001) Cellular compartmentation of ammonium assimilation in rice and barley. J Exp Bot 52:591–604
Turgeon R (1996) Phloem loading and plasmodesmata. Trends Plant Sci 1:418–423
Turgeon R, Hepler PK (1989) Symplastic continuity between mesophyll and companion cells in minor veins of mature Cucurbita pepo L. leaves. Planta 179:24–31
Turgeon R, Webb JA (1976) Leaf development and phloem transport in Cucurbita pepo: maturation of the minor veins. Planta 129:265–269
Turgeon R, Webb JA, Evert RF (1975) Ultrastructure of minor veins in Cucurbita pepo leaves. Protoplasma 83:217–232
Urbina JA, Osorno CE, Rojas A (1990) Inhibition of phosphoenolpyruvate carboxykinase from Trypanosoma (Schizotrypanium) cruzi epimastigotes by 3-mecaptopicolinic acid: in vitro and in vivo studies. Arch Biochem Biophys 282:91–99
Walker RP, Chen Z-H (2002) Phosphoenolpyruvate carboxykinase: structure, function and regulation. Adv Bot Res 38:95–189
Walker RP, Leegood RC (1996) Phosphorylation of phosphoenolpyruvate carboxykinase in plants. Studies in plants with C4 photosynthesis and crassulacean acid metabolism and in germinating seeds. Biochem J 317:653–658
Walker RP, Trevanion SJ, Leegood RC (1995) Phosphoenolpyruvate carboxykinase from higher plants: purification from cucumber and evidence of rapid proteolytic cleavage in extracts from a range of plant tissues. Planta 195:58–63
Walker RP, Acheson RM, Técsi LI, Leegood RC (1997) Phosphoenolpyruvate carboxykinase in C4 plants: its role and regulation. Aust J Plant Physiol 24:459–468
Walker RP, Chen Z-H, Técsi LI, Famiani F, Lea PJ, Leegood RC (1999) Phosphoenolpyruvate carboxykinase plays a role in interactions of carbon and nitrogen metabolism during grape seed development. Planta 210:9–18
Walker RP, Chen Z-H, Johnson KE, Famiani F, Tecsi LI, Leegood RC (2001) Using immunohistochemistry to study plant metabolism: the examples of its use in the localization of amino acids in plant tissues, and of phosphoenolpyruvate carboxykinase and its possible role in pH regulation J Exp Bot 52:565–576
Webb JA, Gorham PR (1964) Translocation of photosynthetically assimilated C14 in straight-necked squash. Plant Physiol 39:663–672
Webb JA, Gorham PR (1965) Radial movement of 14C-translocates from squash phloem. Can J Bot 43:97–103
Whiting G (1938) Development and anatomy of primary structures in the seedling of Cucurbita maxima. Bot Gaz 99:497–528
Winter H, Lohaus G, Heldt HW (1992) Phloem transport of amino acids in relation to their cytosolic levels in barley leaves. Plant Physiol 99:996–1004
Acknowledgments
This research was supported by the Biotechnology and Biological Sciences Research Council, UK (Research Grant RSP07804, and by a David Phillips Fellowship to R.P.W.). Z.-H. Chen and R.P. Walker are joint first authors.
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Chen, ZH., Walker, R.P., Técsi, L.I. et al. Phosphoenolpyruvate carboxykinase in cucumber plants is increased both by ammonium and by acidification, and is present in the phloem. Planta 219, 48–58 (2004). https://doi.org/10.1007/s00425-004-1220-y
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DOI: https://doi.org/10.1007/s00425-004-1220-y