Abstract
Parenchyma cells from tubers of Solanum tuberosum L. convert several externally supplied sugars to starch but the rates vary largely. Conversion of glucose 1-phosphate to starch is exceptionally efficient. In this communication, tuber slices were incubated with either of four solutions containing equimolar [U-¹⁴C]glucose 1-phosphate, [U-¹⁴C]sucrose, [U-¹⁴C]glucose 1-phosphate plus unlabelled equimolar sucrose or [U-¹⁴C]sucrose plus unlabelled equimolar glucose 1-phosphate. C¹⁴-incorporation into starch was monitored. In slices from freshly harvested tubers each unlabelled compound strongly enhanced ¹⁴C incorporation into starch indicating closely interacting paths of starch biosynthesis. However, enhancement disappeared when the tubers were stored. The two paths (and, consequently, the mutual enhancement effect) differ in temperature dependence. At lower temperatures, the glucose 1-phosphate-dependent path is functional, reaching maximal activity at approximately 20 °C but the flux of the sucrose-dependent route strongly increases above 20 °C. Results are confirmed by in vitro experiments using [U-¹⁴C]glucose 1-phosphate or adenosine-[U-¹⁴C]glucose and by quantitative zymograms of starch synthase or phosphorylase activity. In mutants almost completely lacking the plastidial phosphorylase isozyme(s), the glucose 1-phosphate-dependent path is largely impeded. Irrespective of the size of the granules, glucose 1-phosphate-dependent incorporation per granule surface area is essentially equal. Furthermore, within the granules no preference of distinct glucosyl acceptor sites was detectable. Thus, the path is integrated into the entire granule biosynthesis. In vitro C¹⁴C-incorporation into starch granules mediated by the recombinant plastidial phosphorylase isozyme clearly differed from the in situ results. Taken together, the data clearly demonstrate that two closely but flexibly interacting general paths of starch biosynthesis are functional in potato tuber cells.
Abstract from the paper’s OpenAlex record; open copy licensed cc-by-nc. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 11
Claim · model-written summary
Glucose 1-phosphate conversion to starch was exceptionally efficient.
- Taxon
- Solanum tuberosum L.
Solanum tuberosumt0 - Outcome
- Conversion of glucose 1-phosphate to starche0
- Qualifier
- exceptionally efficiente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Conversion of glucose 1-phosphate to starch is exceptionally efficient”
t0“potato (Solanum tuberosum L.)”
Claim · model-written summary
Unlabelled sucrose enhanced labelled glucose 1-phosphate incorporation into starch in fresh tuber slices.
- Taxon
- Solanum tuberosum L.Solanum tuberosumt0
- Organ / stage
- freshly harvested tuberse0
- Treatment
- unlabelled equimolar sucrosee1
- Outcome
- ¹⁴C incorporation into starche0
- Direction
- strongly enhancede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In slices from freshly harvested tubers each unlabelled compound strongly enhanced ¹⁴C incorporation into starch”
e1“[U-¹⁴C]glucose 1-phosphate plus unlabelled equimolar sucrose”
t0“potato (Solanum tuberosum L.)”
Claim · model-written summary
Unlabelled glucose 1-phosphate enhanced labelled sucrose incorporation into starch in fresh tuber slices.
- Taxon
- Solanum tuberosum L.Solanum tuberosumt0
- Organ / stage
- freshly harvested tuberse0
- Treatment
- unlabelled equimolar glucose 1-phosphatee1
- Outcome
- ¹⁴C incorporation into starche0
- Direction
- strongly enhancede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In slices from freshly harvested tubers each unlabelled compound strongly enhanced ¹⁴C incorporation into starch”
e1“[U-¹⁴C]sucrose plus unlabelled equimolar glucose 1-phosphate”
t0“potato (Solanum tuberosum L.)”
Claim · model-written summary
Storage abolished mutual enhancement of starch incorporation.
- Taxon
- Solanum tuberosum L.Solanum tuberosumt0
- Treatment
- tubers were storede0
- Outcome
- enhancemente0
- Direction
- disappearede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“enhancement disappeared when the tubers were stored”
t0“potato (Solanum tuberosum L.)”
Claim · model-written summary
The glucose 1-phosphate path remained functional at lower temperatures and peaked near 20 °C.
- Taxon
- Solanum tuberosum L.Solanum tuberosumt0
- Outcome
- glucose 1-phosphate-dependent pathe0
- Direction
- maximal activitye0
- Value
- approximately 20 °Ce0
- Qualifier
- At lower temperaturese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At lower temperatures, the glucose 1-phosphate-dependent path is functional, reaching maximal activity at approximately 20 °C”
t0“potato (Solanum tuberosum L.)”
Claim · model-written summary
Sucrose route flux rose strongly above 20 °C.
- Taxon
- Solanum tuberosum L.Solanum tuberosumt0
- Outcome
- flux of the sucrose-dependent routee0
- Direction
- strongly increasese0
- Qualifier
- above 20 °Ce0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the flux of the sucrose-dependent route strongly increases above 20 °C”
t0“potato (Solanum tuberosum L.)”
Claim · model-written summary
Mutants lacking plastidial phosphorylase had a largely impeded glucose 1-phosphate path.
- Taxon
- Solanum tuberosum L.Solanum tuberosumt0
- Material
- mutantse0
- Gene
- plastidial phosphorylase isozyme(s)e0
- Outcome
- glucose 1-phosphate-dependent pathe0
- Direction
- largely impedede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In mutants almost completely lacking the plastidial phosphorylase isozyme(s), the glucose 1-phosphate-dependent path is largely impeded”
t0“potato (Solanum tuberosum L.)”
Claim · model-written summary
Glucose 1-phosphate incorporation per granule surface area was equal regardless of granule size.
- Taxon
- Solanum tuberosum L.Solanum tuberosumt0
- Outcome
- glucose 1-phosphate-dependent incorporation per granule surface areae0
- Direction
- essentially equale0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Irrespective of the size of the granules, glucose 1-phosphate-dependent incorporation per granule surface area is essentially equal”
t0“potato (Solanum tuberosum L.)”
Claim · model-written summary
No preference for distinct glucosyl acceptor sites was detected within granules.
- Taxon
- Solanum tuberosum L.Solanum tuberosumt0
- Outcome
- no preference of distinct glucosyl acceptor sites was detectablee0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“within the granules no preference of distinct glucosyl acceptor sites was detectable”
t0“potato (Solanum tuberosum L.)”
Claim · model-written summary
Recombinant plastidial phosphorylase mediated in vitro starch incorporation differed from in situ results.
- Taxon
- Solanum tuberosum L.Solanum tuberosumt0
- Gene
- recombinant plastidial phosphorylase isozymee0
- Outcome
- C¹⁴C-incorporation into starch granulese0
- Direction
- clearly differede0
- Comparator
- in situ resultse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In vitro C¹⁴C-incorporation into starch granules mediated by the recombinant plastidial phosphorylase isozyme clearly differed from the in situ results”
t0“potato (Solanum tuberosum L.)”
Claim · model-written summary
Two interacting starch biosynthesis paths function in potato tuber cells.
- Taxon
- potatoSolanum tuberosume0
- Organ / stage
- tuber cellse0
- Outcome
- two closely but flexibly interacting general paths of starch biosynthesis are functionale0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“two closely but flexibly interacting general paths of starch biosynthesis are functional in potato tuber cells”
The same questions in other papers
sucrose · quality: sugar starch · Solanum tuberosum (potato)Positive and negative results
1 paper in the same direction as this paper · 2 in the opposite direction
- negative
- negative
- positive
glucose · quality: sugar starch · Solanum tuberosum (potato)Results agree
2 papers in the same direction as this paper
- positive
- positive
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.