This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Lichtner, F. T. Articles by Spanswick, R. M. Search for Related Content PubMed PubMed Citation Articles by Lichtner, F. T. Articles by Spanswick, R. M. Agricola Articles by Lichtner, F. T. Articles by Spanswick, R. M.

Articles

Sucrose Uptake by Developing Soybean Cotyledons ¹

Section of Plant Biology, Division of Biological Sciences, Cornell University, Ithaca, New York 14853

Sucrose uptake by excised developing soybean cotyledons shows a biphasic dependence on sucrose concentration. At concentrations less than about 50 millimolar external sucrose, uptake can be described as a carrier-mediated process, with a K_m of 8 millimolar. At higher external sucrose concentrations, a linear dependence becomes apparent, which suggests the participation of a nonsaturable component in total uptake. Sucrose absorption is dependent on the presence of an electrochemical potential gradient for protons since agents interfering with the generation or maintenance of this gradient (NaN₃ or carbonylcyanide-m-chlorophenyl hydrazone) decrease sucrose transport to a level at or below that predicted from the operation of the noncarrier-mediated process alone. The saturable component of sucrose uptake is also sensitive to the sulfhydryl-modifying compounds N-ethylmaleimide and p-chloro-mercuribenzenesulfonate. The thiol-reducing agent diethioerythritol reverses fully the p-chloro-mercuri-benzenesulfonate inhibition, but not that of N-ethyl maleim de. Sucrose transport is sensitive to external pH, being decreased at high pH₀. Since sucrose-induced depolarization of the membrane potential and carrier-mediated sucrose influx show similar pH-dependence, inhibitor sensitivity, and values of K_m for sucrose, a sucrose/proton contransport process appears to operate in developing soybean cotyledon cells. Measurement of free space and intracellular sucrose concentrations in vivo suggests that the carrier-mediated process is fully saturated and that sucrose transport may be limiting for sucrose accumulation by the developing seed.

¹ Supported by National Science Foundation Grant PCM 78-12119 to R.M.S.

This article has been cited by other articles:

				U. Krugel, L. M. Veenhoff, J. Langbein, E. Wiederhold, J. Liesche, T. Friedrich, B. Grimm, E. Martinoia, B. Poolman, and C. Kuhn Transport and Sorting of the Solanum tuberosum Sucrose Transporter SUT1 Is Affected by Posttranslational Modification PLANT CELL, September 1, 2008; 20(9): 2497 - 2513. [Abstract] [Full Text] [PDF]

				S. J. Halperin and K. L. Koster Sugar effects on membrane damage during desiccation of pea embryo protoplasts J. Exp. Bot., July 1, 2006; 57(10): 2303 - 2311. [Abstract] [Full Text] [PDF]

				G. Sriram, D. B. Fulton, V. V. Iyer, J. M. Peterson, R. Zhou, M. E. Westgate, M. H. Spalding, and J. V. Shanks Quantification of Compartmented Metabolic Fluxes in Developing Soybean Embryos by Employing Biosynthetically Directed Fractional 13C Labeling, Two-Dimensional [13C, 1H] Nuclear Magnetic Resonance, and Comprehensive Isotopomer Balancing Plant Physiology, October 1, 2004; 136(2): 3043 - 3057. [Abstract] [Full Text] [PDF]

				A. de Jong and A.C. Borstlap Transport of amino acids (L-valine, L-lysine, L-glutamic acid) and sucrose into plasma membrane vesicles isolated from cotyledons of developing pea seeds J. Exp. Bot., October 1, 2000; 51(351): 1663 - 1670. [Abstract] [Full Text] [PDF]