Abstract
Modification of tuber carbohydrate metabolism by the tuber-specific expression of a yeast invertase targeted to the cytosol or apoplast has previously been demonstrated to have diverse effects on tuber growth and metabolism. In the current study, we generated plants exhibiting tuber-specific expression of the same enzyme targeted to the vacuole. Enzymatic analysis of the carbohydrate levels of the tuber revealed dramatic decreases in sucrose content coupled with large increases in the levels of glucose and hexose phosphates, but unaltered starch content in the transformants. Analysis of the key enzyme of glycolysis suggests that this pathway is down-regulated in the transformants. Despite these changes in metabolite pools and enzyme activity, few consistent changes could be observed in the estimated metabolic fluxes following incubation of isolated tuber discs in labelled glucose. The analysis of the relative levels of a wide range of metabolites using a gas chromatography-mass spectrometry (GC-MS)-based metabolite profiling method revealed large changes in the levels of fructose and decreases in a range of other sugars, but very few changes in the contents of organic and amino acids. This metabolic profile is remarkably consistent with that obtained following expression of the invertase in the apoplastic compartment, providing circumstantial evidence for the endocytotic trafficking of sugars within potato tuber parenchyma. Finally, the results of this study are compared with those from other plant species and the relative roles of the vacuolar isoform of the enzyme are contrasted.
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Claims 10
Claim · model-written summary
Transformant tubers had dramatically lower sucrose content.
- Taxon
- Potato
Solanum tuberosumt0 - Treatment
- transformantse0
- Outcome
- sucrose contente0
- Direction
- decreasese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Enzymatic analysis of the carbohydrate levels of the tuber revealed dramatic decreases in sucrose content coupled with large increases in the levels of glucose and hexose phosphates, but unaltered starch content in the transformants.”
t0“Potato”
Claim · model-written summary
Transformant tubers had large increases in glucose and hexose phosphate levels.
- Taxon
- PotatoSolanum tuberosumt0
- Treatment
- transformantse0
- Outcome
- levels of glucose and hexose phosphatese0
- Direction
- increasese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Enzymatic analysis of the carbohydrate levels of the tuber revealed dramatic decreases in sucrose content coupled with large increases in the levels of glucose and hexose phosphates, but unaltered starch content in the transformants.”
t0“Potato”
Claim · model-written summary
Starch content was unchanged in transformant tubers.
- Taxon
- PotatoSolanum tuberosumt0
- Treatment
- transformantse0
- Outcome
- starch contente0
- Direction
- unalterede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“but unaltered starch content in the transformants.”
t0“Potato”
Claim · model-written summary
Analysis of a glycolytic enzyme suggested down regulation of glycolysis in transformants.
- Taxon
- PotatoSolanum tuberosumt0
- Gene
- key enzyme of glycolysise0
- Outcome
- this pathway is down-regulatede0
- Direction
- down-regulatede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Analysis of the key enzyme of glycolysis suggests that this pathway is down-regulated in the transformants.”
t0“Potato”
Claim · model-written summary
Estimated metabolic fluxes showed few consistent changes in isolated transformant tuber discs.
- Taxon
- PotatoSolanum tuberosumt0
- Treatment
- transformantse1
- Outcome
- estimated metabolic fluxese0
- Direction
- few consistent changese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“few consistent changes could be observed in the estimated metabolic fluxes following incubation of isolated tuber discs in labelled glucose.”
t0“Potato Tuber has only Minor Effects on Metabolism”
e1“Enzymatic analysis of the carbohydrate levels of the tuber revealed dramatic decreases in sucrose content coupled with large increases in the levels of glucose and hexose phosphates, but unaltered starch content in the transformants.”
Claim · model-written summary
Metabolite profiling showed large changes in fructose levels.
- Taxon
- PotatoSolanum tuberosumt0
- Outcome
- levels of fructosee0
- Direction
- large changese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“revealed large changes in the levels of fructose and decreases in a range of other sugars, but very few changes in the contents of organic and amino acids.”
t0“Potato”
Claim · model-written summary
Metabolite profiling showed decreases in other sugars.
- Taxon
- PotatoSolanum tuberosumt0
- Outcome
- a range of other sugarse0
- Direction
- decreasese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“revealed large changes in the levels of fructose and decreases in a range of other sugars, but very few changes in the contents of organic and amino acids.”
t0“Potato”
Claim · model-written summary
Organic and amino acid contents showed very few changes.
- Taxon
- PotatoSolanum tuberosumt0
- Outcome
- contents of organic and amino acidse0
- Direction
- very few changese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“but very few changes in the contents of organic and amino acids.”
t0“Potato”
Claim · model-written summary
The vacuolar invertase metabolic profile resembled that of apoplastic invertase expression.
- Taxon
- PotatoSolanum tuberosumt0
- Outcome
- metabolic profilee0
- Comparator
- expression of the invertase in the apoplastic compartmente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This metabolic profile is remarkably consistent with that obtained following expression of the invertase in the apoplastic compartment”
t0“Potato”
Claim · model-written summary
Profile similarity provides circumstantial evidence for endocytotic sugar trafficking in potato tuber parenchyma.
- Taxon
- potatoSolanum tuberosume0
- Organ / stage
- tuber parenchymae0
- Outcome
- endocytotic trafficking of sugarse0
- Qualifier
- circumstantial evidencee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“providing circumstantial evidence for the endocytotic trafficking of sugars within potato tuber parenchyma.”
The same questions in other papers
transgenic · quality: sugar starch · Solanum tuberosum (potato)Positive and negative results
11 papers in the same direction as this paper · 2 in the opposite direction
- negative
- negative
- no effect
10 papers more in this group
See all 14 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.