Abstract
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 [(14)C]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.
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Claims 7
Claim · model-written summary
UMPS suppression restricted de novo pyrimidine synthesis from orotate.
- Taxon
- potato (Solanum tuberosum)
Solanum tuberosume1 - Treatment
- Decreased expression of UMPSe0
- Gene
- UMPSe0
- Outcome
- use of externally supplied orotate for de novo pyrimidine synthesise0
- Direction
- restrictede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Decreased expression of UMPS restricted the use of externally supplied orotate for de novo pyrimidine synthesis in tuber tissue”
e1“potato (Solanum tuberosum) tubers”
Claim · model-written summary
UMPS suppression stimulated uridine salvage.
- Taxon
- potato (Solanum tuberosum)Solanum tuberosume1
- Treatment
- Decreased expression of UMPSe0
- Gene
- UMPSe0
- Outcome
- uridine-salvaging pathwaye0
- Direction
- stimulatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“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.”
e1“potato (Solanum tuberosum) tubers”
Claim · model-written summary
Tuber uridine nucleotide levels increased.
- Taxon
- potato (Solanum tuberosum)Solanum tuberosume1
- Outcome
- levels of tuber uridine nucleotidese0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increased levels of tuber uridine nucleotides”
e1“potato (Solanum tuberosum) tubers”
Claim · model-written summary
Sucrose flux to starch and cell walls increased.
- Taxon
- potato (Solanum tuberosum)Solanum tuberosume1
- Outcome
- fluxes of [(14)C]sucrose to starch and cell wall synthesise0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increased fluxes of [(14)C]sucrose to starch and cell wall synthesis”
e1“potato (Solanum tuberosum) tubers”
Claim · model-written summary
Tuber starch and cell wall components increased.
- Taxon
- potato (Solanum tuberosum)Solanum tuberosume1
- Outcome
- amounts of starch and cell wall componentse0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increased amounts of starch and cell wall components in the tubers”
e1“potato (Solanum tuberosum) tubers”
Claim · model-written summary
Leaf uridine nucleotide levels did not change.
- Taxon
- potato (Solanum tuberosum)Solanum tuberosume1
- Organ / stage
- leavese0
- Outcome
- uridine nucleotide levelse0
- Direction
- no changese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“there were no changes in uridine nucleotide levels in leaves”
e1“potato (Solanum tuberosum) tubers”
Claim · model-written summary
UMPS suppression raised transcripts of three pyrimidine-related enzymes.
- Taxon
- potato (Solanum tuberosum)Solanum tuberosume1
- Treatment
- Decreased expression of UMPSe0
- Gene
- carbamoylphosphate synthase, uridine kinase, and uracil phosphoribosyltransferasee0
- Outcome
- transcript levelse0
- Direction
- increasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Decreased expression of UMPS in tubers led to an increase in transcript levels of carbamoylphosphate synthase, uridine kinase, and uracil phosphoribosyltransferase”
e1“potato (Solanum tuberosum) tubers”
The same questions in other papers
transgenic · molecular: expression · Solanum tuberosum (potato)Positive and negative results
3 papers in the same direction as this paper · 5 in the opposite direction
- negative
- no effect
- negative
5 papers more in this group
See all 9 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.