Abstract
The cellular pathway of postphloem sugar transport was elucidated in the outer pericarp of tomato (Lycopersicon esculentum Mill cv. Floradade) fruit at 13–14 and 23–25 days after anthesis (DAA). These developmental stages are characterized by phloem-imported sugars being accumulated as starch and hexose, respectively. The symplasmic tracer, 5(6)-carboxyfluorescein, loaded into the storage parenchyma cells of pericarp discs, moved readily in the younger fruit but was immobile in fruit at 23–25 DAA. Symplasmic mobility of [14C]glucose was found to be identical to 5(6)-carboxyfluorescein. For the older fruit, the pericarp apoplasm was shown to be freely permeable to the apoplasmic tracer, trisodium 3-hydroxy-5,8,10-pyrenetrisulfonate. Indeed, the transport capacity of the pericarp apoplasm was such that the steady-state rate of in-vitro glucose uptake by pericarp discs accounted fully for the estimated rate of in-vivo glucose accumulation. For fruit at 23–25 DAA, the inhibitory effects of the sulfhydryl group modifier, p-chloromer-curibenzenesulfonic acid (PCMBS), on [14C]glucose and [14C]fructose uptake by the pericarp discs depended on the osmolality of the external solution. The inhibition was most pronounced for pericarp discs enriched in storage parenchyma. Consistent with the PCMBS study, strong fluorescent signals were exhibited by the storage parenchyma cells of pericarp discs exposed to the membrane-impermeable thiol-binding fluorochrome, mono-bromotrimethylammoniobimane. The fluorescent weak acid, sulphorhodamine G, was accumulated preferentially by the storage parenchyma cells. Accumulation of sulphorhodamine G was halted by the ATPase inhibitor erythrosin B, suggesting the presence of a plasma-membrane-bound H+-ATPase. A linkage between the putative H+-ATPase activity and hexose transport was demonstrated by an erythrosin-B inhibition of [14C]glucose and [14C]fructose uptake. In contrast, comparable evidence for an energy-coupled hexose porter could not be found in the pericarp of younger fruit at 13–14 DAA. Overall, the data are interpreted to indicate that: (i) The postphloem cellular pathway in the outer fruit pericarp shifts from the symplasm during starch accumulation (13–14 DAA) to the apoplasm for rapid hexose accumulation (23–25 DAA). (ii) An energy-coupled plasma-membrane hexose carrier is expressed specifically in storage parenchyma cells at the latter stage of fruit development.
Similar content being viewed by others
Abbreviations
- CF:
-
5(6)-carboxyfluorescein
- CFDA:
-
5(6)-car-boxyfluorescein diacetate
- DAA:
-
days after anthesis
- EB:
-
erythrosin B
- PCMBS:
-
p-chloromercuribenzenesulfonic acid
- PTS:
-
trisodium 3-hydroxy-5,8,10-pyrenetrisulfonate
- qBBr:
-
monobromotrimethylammoniobimane
- SE-CC:
-
sieve element-companion cell
- SRG:
-
sulphorhodamine G
References
Aloni, B., Wyse, R.E., Griffith, S. (1986) Sucrose transport and phloem unloading in stems of Vicia faba: Possible involvement of a sucrose carrier and osmotic regulation. Plant Physiol. 81, 482–486
Bangerth, F., Ho, L.C. (1984) Fruit position and fruit set sequences in a truss as factors determining final size of tomato fruit. Ann. Bot. 53, 315–319
Beffagna, N., Romani, G. (1988) Effect of two plasmalemma ATPase inhibitors on H+ extrusion and intracellular pH in Elodea densa leaves. J. Exp. Bot. 39, 1033–1043
Bush, D.R. (1993) Proton-coupled sugar and amino acid transporters in plants. Anna Rev. Plant Physiol. Plant Mol. Biol. 44, 513–542
Canny, M.J. (1987) Locating active proton extrusion pumps in leaves. Plant Cell Environ. 10, 271–274
Canny, M. J. (1988) Bundle sheath tissues of legume leaves as a site of recovery of solutes from the transpiration stream. Physiol. Plant. 73, 457–464
Cocucci, M.C. (1986) Inhibition of plasma membrane and tonoplast ATPase by erythrosin B. Plant Sci. 47, 21–26
Dali, N., Michaud, D., Yelle, S. (1992) Evidence for the involvement of sucrose phosphate synthase in the pathway of sugar accumulation in sucrose-accumulating tomato fruits. Plant Physiol. 99, 434–438
Damon, S., Hewitt, J., Nieder, M., Bennett, A.B. (1988) Sink metabolism in tomato fruit. II Phloem unloading and sugar uptake.Plant Physiol. 87, 731–736
Delrot, S., Pichelin, D., M'Batchi, B. (1986) The use of thiol reagents in the study of the sucrose carrier. In: Plant biology, vol. 1: Phloem transport, pp. 41–46, Cronshaw, J., Lucas, W.J., Giaquinta, R.T. eds. Alan Liss Inc, New York
Diettrich, B., Keller, F. (1991) Carbohydrate transport in discs of storage parenchyma of celery petioles. New Phytol. 117, 413–422
Dybing, D.C., Currier, H.B. (1961) Foliar penetration by chemicals. Plant Physiol. 36, 169–174
Eastman, P.A.K., Peterson, C.A., Dengler, N.G. (1988) Suberized bundle sheath in grasses (Poaceae) of different photosynthate types. II. Apoplatic permeability. Protoplasma 142, 112–126
Fieuw, S., Willenbrink, J. (1990) Sugar transport and sugar metabolizing enzymes in sugar beet storage roots (Beta vulgaris ssp. altissima). J. Plant Physiol. 137, 216–223
Fieuw, S., Willenbrink, J. (1991) Isolation of protoplasts from tomato fruit (Lycopersicon esculentum): first uptake studies. Plant Sci. 76, 9–17
Fried, B., Sherma, J. (1982) Thin-layer chromatography. Techniques and applications. Marcel Dekker, Inc., New York
Ghebregzabher, M., Rufini, S., Monaldi, B., Lato, M. (1976) Thin-layer chromatography of carbohydrates. J. Chrom. 127, 133–162
Giaquinta, R. (1976) Evidence for phloem loading from apoplast: Chemical modification of membrane sulfhydryl groups. Plant Physiol. 57, 872–875
Goodall, H., Johnson, M.H. (1982) Use of carboxyfluorescein diacetate to study formation of permeable channels between mouse blastomeres. Nature 295, 524–526
Grunwaldt, G., Ehwald, R., Goring, H. (1982) Suitability of the osmotic shock procedure for the analysis of membrane transport in root tips of Zea mays L. J. Exp. Bot. 29, 97–106
Hawker, J.S. (1985) Sucrose. In: Biochemistry of storage carbohyrates in green plants, pp. 1–51, Dey, P.M., Dixon, R.A., eds. Academic Press, London New York
Ho, L.C. (1988) Metabolism and compartmentation of imported sugar in sink organs in relation to sink strength. Annu. Rev. Plant Physiol. Plant Mol. Biol. 39, 355–378
Ho, L. C. (1993) Uptake and transport of calcium and the possible causes of blossom-end rot in tomato. J. Exp. Bot. 44, 509–518
Ho, L.C., Hewitt, J.D. (1986) Fruit development. In: The tomato crop: a scientific basis for improvement, pp. 202–226, Atherton, J.C., Rudich, J., eds. Chapman and Hall, London
Ho, L.C., Grange, R.I., Picken, A.J. (1987) An analysis of the accumulation of water and dry matter in tomato fruit. Plant Cell Environ. 10, 157–162
Ho, L.C., Lecharny, A., Willenbrink, L. (1991) Sucrose cleavage in relation to import and metabolism of sugars in sink organs. In: Recent advances in phloem transport and assimilate compartmentation, pp. 178–186, Bonnemain, J.L., Delrot, S., Lucas, W.J., Dainty, J., eds. Ouest Editions, Paris
Iki, K., Sekiguchi, K., Kurata, K., Tada, T., Nakagawa, H., Ogura, N. (1978) Immunological properties of β-fructofuranosidase from ripening tomato fruit. Phytochemistry 17, 311–312
Johnson, C., Hall, J.L., Ho, L.C. (1988) Pathways of uptake and accumulation of sugars in tomato fruit. Ann. Bot. 61, 593–603
Koswer, N.S., Koswer, E.M. (1987) Thiol labelling bromobimanes. Methods Enzymol. 143, 76–84
Lide, D.R. (1990) Handbook of Chemistry and Physics, 71st Edn., pp. 6–151, CRC Press, Boston
Minchin, P.E.H., Thorpe, M.R. (1984) Apoplastic phloem unloading in the stem of bean. J. Exp. Bot. 35, 538–550
Offler, C.E., Horder, B.A. (1992) The cellular pathway of short-distance transfer of photosynthates in developing tomato fruit(Abstr.). Plant Physiol. 99, Suppl. 241
Patrick, J.W. (1990) Sieve element unloading: cellular pathway, mechanism and control. Physiol. Plant. 78, 298–308
Peterson, C.A., Griffith, M., Huner, N.P.A. (1985) Permeability of the suberized mestome sheath in winter rye. Plant Physiol. 77, 157–161
Rausch, T. (1991) The hexose transporters at the plasma membrane and the tonoplast of higher plants. Physiol. Plant 82, 134–142
Richter, E., Ehwald, E. (1983) Apoplastic mobility of sucrose in storage parenchyma of sugar beet. Physiol. Plant. 58, 263–268
Riesmeier, J.W., Willmitzer, L., Frommer, W.B. (1992) Isolation and characterization of a sucrose carrier cDNA from spinach by functional expression in yeast. EMBO 11, 4705–4713
Robards, A.W., Lucas, W.J. (1990) Plasmodesmata. Annu. Rev. Plant Physiol. Plant Mol. Biol. 41, 369–419
Sauer, N., Kriedlander, K., Graml-Wicke, U. (1990) Primary structure, genomic organization and heterologous expression of a glucose transporter from Arabidopsis thaliana. EMBO 9, 3045–3050
van Bel, A.J.E., Ammerlaan, A., van Dijk, A., (1994) A three-step screening procedure to identify the mode of phloem loading in intact leaves: Evidence for symplasmic and apoplasmic phloem loading associated with the type of companion cell. Planta 192, 31–39
van Bel, A.J.E., van Rijen, H.V.M. (1994) Microelectrode-recorded development of the symplasmic autonomy of the sieve element/companion cell complex in the stem phloem of Lupinus luteus L. Planta 192, 165–175
Wood, R.M. (1992) Transfer of photosynthates and potassium in the elongating stem of Phaseolus vulgaris L. Ph.D. thesis. The University of Newcastle, NSW 2308, Australia
Wyse, R., Zamski, E., Tomos, A.D. (1986) Turgor regulation of transport in sugar beet taproot tissue. Plant Physiol. 81, 478–481
Author information
Authors and Affiliations
Additional information
Y.L.R. thanks The University of Newcastle and Department of Education, Employment and Training of the Australian Government for a Postgraduate Research Scholarship and an Overseas Postgraduate Research Award respectively. Valuable comments by Drs C.J. Brady and C.E. Offler on an earlier draft of the manuscript were much appreciated. The work was partially supported by a grant from the Research Management Committee, The University of Newcastle.
Rights and permissions
About this article
Cite this article
Ruan, YL., Patrick, J.W. The cellular pathway of postphloem sugar transport in developing tomato fruit. Planta 196, 434–444 (1995). https://doi.org/10.1007/BF00203641
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00203641