Abstract
The aim of this work was to discover which compound(s) cross the amyloplast envelope to supply the carbon for starch synthesis in grains of Triticum aestivum L. Amyloplasts were isolated, on a continuous gradient of Nycodenz, from lysates of protoplasts of endosperm of developing grains, and then incubated in solutions of 14C-labelled: glucose, glucose 1-phosphate, glucose 6-phosphate, fructose 6-phosphate, fructose-1,6-bisphosphate, dihydroxyacetone phosphate and glycerol 3-phosphate. Only glucose 1-phosphate gave appreciable labelling of starch that was dependent upon the integrity of the amyloplasts. Incorporation into starch was linear with respect to time for 2 h. At the end of the incubations, 98% of the 14C in the soluble fraction of the incubation mixture was recovered as [14C]glucose 1-phosphate. Thus it is unlikely that the added [14C glucose 1-phosphate was extensively metabolized prior to uptake by the amyloplasts. It is argued that the behaviour of the isolated amyloplasts, and previously published data on the labelling of starch by [13C]glucose, are consistent with the view that in wheat grains it is a C-6, not a C-3, compound that enters the amyloplast to provide the carbon for starch synthesis.
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Abbreviations
- PPase:
-
alkaline inorganic pyrophosphatase
- UDPglucose:
-
uridine 5′-diphosphoglucose
References
ap Rees, T. (1977) Conservations of carbohydrate by the nonphotosynthetic cells of higher plants. Symp. Soc. Exp. Biol. 31, 7–32
Bartlett, G.R. (1959) Methods for the isolation of glycolytic intermediates by column chromatography with ion exchange resins. J. Biol. Chem. 234, 459–465
Boyer, C.D. (1985) Synthesis and breakdown of starch: In: Biochemical basis of plant breeding, vol. 1, pp. 133–153, Neyra, C.A. ed. CRC Press Inc, Boca Raton
Dancer, J.E. (1987) The role of pyrophosphate fructose 6-phosphate: 1-phosphotransferase in plants. Ph.D. thesis, University of Cambridge, UK
Downton, W.J.S., Hawker, J.S. (1973) Enzymes of starch metabolism in leaves and berries of Vitis vinifera. Phytochemistry 12, 1557–1563
Echeverria, E., Boyer, C., Shannon, J. (1985) Enzymatic content and starch synthetic capacity of isolated maize amyloplasts. (Abstr.) Plant Physiol. 77, Suppl., 109
Edwards, J., ap Rees, T. (1986) Metabolism of UDP-glucose by developing embryos of round and wrinkled varieties of Pisum sativum. Phytochemistry 25, 2033–2039
Entwistle, G., Tyson, R.H., ap Rees, T. (1988) Isolation of amyloplasts from wheat endosperm. Phytochemistry, 27, 993–996
Gerhardt, R., Stitt, M., Heldt, H.W. (1987) Subcellular metabolite levels in spinach leaves. Plant Physiol. 83, 399–407
Ghosh, H.P., Preiss, J. (1965) Biosynthesis of starch in spinach chloroplasts. Biochemistry 4, 1354–1361
Gross, P., ap Rees, T. (1986) Alkaline inorganic pyrophosphatase and starch synthesis in amyloplasts. Planta 167, 140–145
Journet, E.-P., Douce, R. (1985) Enzymic capacities of purified cauliflower bud plastids for lipid synthesis and carbohydrate metabolism. Plant Physiol. 79, 458–467
Keeling, P.L., Tyson, R.H., Bridges, I.G. (1983) Evidence for the involvement of triose phosphates in the pathway of starch biosynthesis in developing wheat grain. Biochem. Soc. Trans. 11, 791–792
Macdonald, F.D., ap Rees, T. (1983) Enzymic properties of amyloplasts from suspension cultures of soybean. Biochim. Biophys. Acta 755, 81–89
Macdonald, F.D., Preiss, J. (1985) Solubilization of the starchgranule bound starch synthase of normal maize kernels. Plant Physiol. 73, 175–178
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Tyson, R.H., ap Rees, T. Starch synthesis by isolated amyloplasts from wheat endosperm. Planta 175, 33–38 (1988). https://doi.org/10.1007/BF00402879
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DOI: https://doi.org/10.1007/BF00402879