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          Institute: MPI für molekulare Pflanzenphysiologie     Collection: Publikationen Pflanzenphysiologie     Display Documents

ID: 251447.0, MPI für molekulare Pflanzenphysiologie / Publikationen Pflanzenphysiologie
Modulation of fructokinase activity of potato (Solanum tuberosum) results in substantial shifts in tuber metabolism
Authors:Davies, H. V.; Shepherd, L. V. T.; Burrell, M. M.; Carrari, F.; Urbanczyk-Wochniak, E.; Leisse, A.; Hancock, R. D.; Taylor, M.; Viola, R.; Ross, H.; McRae, D.; Willmitzer, L.; Fernie, A. R.
Date of Publication (YYYY-MM-DD):2005-07
Title of Journal:Plant and Cell Physiology
Journal Abbrev.:Plant Cell Physiol
Issue / Number:7
Start Page:1103
End Page:1115
Review Status:not specified
Audience:Not Specified
Abstract / Description:Potato plants (Solanum tuberosum L. cvs Desiree and Record) transformed with sense and antisense constructs of a cDNA encoding the potato fructokinase StFK1 exhibited altered transcription of this gene, altered amount of protein and altered enzyme activities. Measurement of the maximal catalytic activity of fructokinase revealed a 2-fold variation in leaf (from 90 to 180% of wild type activity) and either a 10- or 30-fold variation in tuber (from 10 or 30% to 300% in Record and Desiree, respectively) activity. The comparative effect of the antisense construct in leaf and tuber tissue suggests that this isoform is only a minor contributor to the total fructokinase activity in the leaf but the predominant isoform in the tuber. Antisense inhibition of the fructokinase resulted in a reduced tuber yield; however, its overexpression had no impact on this parameter. The modulation of fructokinase activity had few, consistent effects on carbohydrate levels, with the exception of a general increase in glucose content in the antisense lines, suggesting that this enzyme is not important for the control of starch synthesis. However, when metabolic fluxes were estimated, it became apparent that the transgenic lines display a marked shift in metabolism, with the rate of redistribution of radiolabel to sucrose markedly affected by the activity of fructokinase. These data suggest an important role for fructokinase, acting in concert with sucrose synthase, in maintaining a balance between sucrose synthesis and degradation by a mechanism independent of that controlled by the hexose phosphate-mediated activation of sucrose phosphate synthase.
Free Keywords:carbohydrate metabolism
; fructokinase
; glycolysis
; solanum tuberosum
; starch synthesis
; low internal oxygen
; sucrose synthase
; starch synthesis
; plastidial phosphoglucomutase
; transgenic plants
; carbohydrate-metabolism
; antisense inhibition
; tomato fruit
; hexokinase
; expression
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für molekulare Pflanzenphysiologie/Molekulare Physiologie/AG Willmitzer/Fernie
External Affiliations:Max Planck Inst Mol Pflanzenphysiol, Muhlenberg 1, D-14476 Golm, Germany
Max Planck Inst Mol Pflanzenphysiol, D-14476 Golm, Germany
Scottish Crop Res Inst, Qual Hlth & Nutr Programme, Dundee DD2 5DA, Scotland
Univ Sheffield, Dept Anim & Plant Sci, Sheffield S10 2TN, S Yorkshire, England
Identifiers:ISI:000230757100009 [ID No:1]
ISI:000230757100009 [ID No:2]
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