Abstract
Autoradiographs obtained from discs from mature, peeled Ipomoea tricolor Cav. leaves indicated that a 15-min 2 mM p−chloromercuribenzene sulfonic acid (PCMBS) pretreatment did not prevent the accumulation of 14CO2−derived 14C-photosynthate within the minor veins. However, accumulation of 14C-photosynthate within these veins was almost, or completely prevented by treatment of the leaf discs at pH 9.0. Peeled Ipomoea leaf discs were also used to study the kinetics of exogenously supplied [14C]sucrose; influx occurred by the combined operation of a saturable and a first-order kinetic mechanism. Both transport mechanisms were inhibited by a 15-min 2 mM PCMBS pretreatment or by treatment at pH 9.0. An analysis of autoradiographs obtained on leaf discs that had been fed exogenous [14C]sucrose, showed that whereas all cells of the leaf took up sucrose at pH 5.0, uptake at pH 9.0 occurred primarily into cells of the minor veins. In contrast with 14C-photoassimilate experiments, PCMBS pretreatment, at either pH 5.0 or pH 9.0, resulted in a reduction in the radioactivity within the minor veins when the label was supplied exogenously as [14C]sucrose. Kinetic experiments conducted with mesophyll cells isolated enzymatically from peeled source-leaf discs indicated that [14C]sucrose influx also occurred by a saturable and a first-order kinetic mechanism. Comparative studies between leaf discs and isolated mesophyll cells showed that mesophyll cells could account for 75% of the total uptake occurring into the peeled leaf discs. These results indicate that the effects of PCMBS and alkaline pH on net sucrose uptake by leaf tissues are not exerted solely on phloem tissues, and that some of the effects of these treatments may be attributable to an inhibition of symplasmic transport to the minor veins.
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Abbreviations
- PCMBS:
-
p−chloromercuribenzene sulfonic acid
References
Belitser, N.V., Zaalishvili, G.V., Sytnianskaja, N.P. (1982) Ca2+ binding sites and Ca2+−ATPase activity in barley root tip cells. Protoplasma 111, 63–78
Berridge, M.J. (1984) Inositol trisphosphate and diacylglycerol as second messengers. Biochem. J. 220, 345–360
Carlier, G., Thellier, M. (1979) Lithium-perturbation of the induction of a methyl-glucose transport during aging of foliar leaf disks of Pelargonium zonale (L.) Aiton. Physiol. Vég. 17, 13–26
Drobak, B.K., Ferguson, I.B. (1985) Release of Ca2+ from plant hypocotyl microsomes by inositol-1,4,5-trisphosphate. Biochem. Biophys. Res. Commun. 130, 1241–1246
Erwee, M.G., Goodwin, P.B. (1983) Characterization of the Egeria densa Planch. leaf symplast. Inhibition of the intercellular movement of fluorescent probes by group II ions. Planta 158, 320–328
Erwee, M.G., Goodwin, P.B. (1984) Characterization of the Egeria densa leaf symplast: Response to plasmolysis, deplasmolysis and to aromatic amino acids. Protoplasma 122, 162–168
Erwee, M.G., Goodwin, P.B., Van Bel, A.J.E. (1985) Cell-cell communication in the leaves of Commelina cyanea and other plants. Plant Cell Environ. 8, 173–178
Fondy, B.R., Geiger, D.R. (1977) Sugar selectivity and other characteristics of phloem loading in Beta vulgaris L. Plant Physiol. 59, 953–960
Giaquinta, R.T. (1977) Phloem loading of sucrose. pH dependence and selectivity. Plant Physiol. 59, 750–753
Giaquinta, R.T. (1983) Phloem loading of sucrose. Annu. Rev. Plant Physiol. 34, 347–387
Grusak, M.A., Lucas, W.J. (1984) Recovery of cold-inhibited phloem translocation in sugar beet. I. Experimental analysis of an existing mathematical recovery model. J. Exp. Bot. 35, 389–402
Kauss, H., Kohle, H., Jablick, W. (1983) Proteolytic activation and stimulation by Ca2+ of glucan synthase from soybean cells. FEBS Lett. 158, 84–88
Leger, A., Delrot, S., Bonnemain, J.-L. (1982) Properties of sugar uptake by wheat leaf fragments: effects of ageing and pH dependence. Physiol. Vég. 20, 651–659
Lemoine, R., Delrot, S., Auger, E. (1984) Development of pH sensitivity of sucrose uptake during ageing of Vicia faba leaf discs. Physiol. Plant. 61, 571–576
Lucas, W.J. (1985) Phloem-loading: A metaphysical phenomenon? In: Regulation of carbon partitioning in photosynthetic tissue, pp. 254–271, Heath, R.L., Preiss, J., eds. American Society of Plant Physiologists. Rockville, Md., USA
Lucas, W.J., Madore, M.A. (1987) Recent advances in sugar transport. In: The biochemistry of plants, a comprehensive treatise, vol. 12: Carbohydrates, Preiss, J., ed. Academic Press, New York (in press)
Madore, M.A., Grodzinski, B. (1984) Effects of oxygen concentration on 14C-photoassimilate transport from leaves of Salvia splendens L. Plant Physiol. 76, 782–786
Madore, M.A., Oross, J.W., Lucas, W.J. (1986) Symplastic transport in Ipomoea tricolor source leaves: demonstration of functional symplastic connections from mesophyll to minor veins by a novel dye tracer method. Plant Physiol. 82, 432–442
Madore, M.A., Webb, J.A. (1981) Leaf free space analysis and vein loading in Cucurbita pepo. Can. J. Bot. 59, 2550–2557
Madore, M.A., Webb, J.A. (1982) Stachyose synthesis in isolated mesophyll cells of Cucurbita pepo. Can. J. Bot. 60, 126–130
Maynard, J.W., Lucas, W.J. (1982) Sucrose and glucose uptake into Beta vulgaris leaf tissues. A case for general (apoplastic) retrieval systems. Plant Physiol. 70, 1436–1443
Morrow, D.L., Lucas, W.J. (1986) (1−>3)-β-D-Glucan synthase from sugar beet. I. Isolation and solubilization. Plant Physiol. 81, 171–176
Turgeon, R. (1984) Efflux of sucrose from minor veins of tobacco leaves. Planta 161, 120–128
Van Bel, A.J.E., Ammerlaan, A., Blaauw-Jansen, G. (1986) Preferential accumulation by mesophyll cells at low and high exogenous amino acid and sugar concentrations in Commelina benghalensis L. leaves. J. Exp. Bot. 37, 1899–1910
Wilson, C., Oross, J.W., Lucas, W.J. (1985) Sugar uptake into Allium cepa leaf tissue: an integrated approach. Planta 164, 227–240
Zocchi, G., Rogers, S.A., Hanson, J.B. (1983) Inhibition of proton pumping in corn roots is associated with increased phosphorylation of membrane proteins. Plant Sci. Lett. 31, 215–221
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Madore, M.A., Lucas, W.J. Control of photoassimilate movement in source-leaf tissues of Ipomoea tricolor Cav. . Planta 171, 197–204 (1987). https://doi.org/10.1007/BF00391094
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DOI: https://doi.org/10.1007/BF00391094