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

ID: 251397.0, MPI für molekulare Pflanzenphysiologie / Publikationen Pflanzenphysiologie
Inhibition of de novo pyrimidine synthesis in growing potato tubers leads to a compensatory stimulation of the pyrimidine salvage pathway and a subsequent increase in biosynthetic performance
Authors:Geigenberger, P.; Regierer, B.; Nunes-Nesi, A.; Leisse, A.; Urbanczyk-Wochniak, E.; Springer, F.; van Dongen, J. T.; Kossmann, J.; Fernie, A. R.
Date of Publication (YYYY-MM-DD):2005-07
Title of Journal:Plant Cell
Journal Abbrev.:Plant Cell
Issue / Number:7
Start Page:2077
End Page:2088
Review Status:not specified
Audience:Not Specified
Abstract / Description:Pyrimidine nucleotides are of general importance for many aspects of cell function, but their role in the regulation of biosynthetic processes is still unclear. In this study, we investigate the influence of a decreased expression of UMP synthase (UMPS), a key enzyme in the pathway of de novo pyrimidine synthesis, on biosynthetic processes in growing potato (Solanum tuberosum) tubers. Transgenic plants were generated expressing UMPS in the antisense orientation under the control of the tuber-specific patatin promoter. Lines were selected with markedly decreased expression of UMPS in the tubers. Decreased expression of UMPS restricted the use of externally supplied orotate for de novo pyrimidine synthesis in tuber tissue, whereas the uridine-salvaging pathway was stimulated. This shift in the pathways of UMP synthesis was accompanied by increased levels of tuber uridine nucleotides, increased fluxes of [C-14] sucrose to starch and cell wall synthesis, and increased amounts of starch and cell wall components in the tubers, whereas there were no changes in uridine nucleotide levels in leaves. Decreased expression of UMPS in tubers led to an increase in transcript levels of carbamoylphosphate synthase, uridine kinase, and uracil phosphoribosyltransferase, the latter two encoding enzymes in the pyrimidine salvage pathways. Thus, the results show that antisense inhibition of the de novo pathway of pyrimidine synthesis leads to a compensatory stimulation of the less energy-consuming salvage pathways, probably via increased expression and activity of uridine kinase and uracil phosphoribosyltransferase. This results in increased uridine nucleotide pool levels in tubers and improved biosynthetic performance.
Free Keywords:low internal oxygen
; starch synthesis
; sucrose degradation
; solanum-tuberosum
; plastidial phosphoglucomutase
; glucose pyrophosphorylase
; nucleotide-metabolism
; arabidopsis-thaliana
; ump synthase
; expression
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für molekulare Pflanzenphysiologie/Metabolische Netzwerke/AG Geigenberger
MPI für molekulare Pflanzenphysiologie/Molekulare Physiologie/AG Willmitzer/Fernie
External Affiliations:Max Planck Inst Mol Plant Physiol, D-14476 Golm, Germany
Max Planck Inst Mol Plant Physiol, D-14476 Golm, Germany
Univ Stellenbosch, Dept Bot & Zool, Inst Plant Biotechnol, ZA-7601 Maiteland, South Africa
Identifiers:ISI:000230165400018 [ID No:1]
ISI:000230165400018 [ID No:2]
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