Abstract
Abstract Photosynthetic carbon assimilation, carbon partitioning and foliar carbon budgets were measured in the leaves of transformed tomato plants expressing a maize sucrose-phosphate synthase (SPS) gene in addition to the native enzyme, and in untransformed controls. The maize SPS gene was expressed under control of either the promoter of the small subunit of ribulose 1,5-bisphosphate carboxylase (rbcS promoter; lines 2, 9 and 18) or the 35S promoter from cauliflower mosaic virus (CaMV promoter; line 13). The rate of sucrose synthesis was increased relative to that of starch and sucrose/starch ratios were higher throughout the photoperiod in the leaves of all plants expressing high SPS activity. The leaf carbon budget over the day/night cycle in air at low irradiance (180μmol photon m−2 s−1) was similar in all plants. Net photosynthesis measured in air and at elevated CO2 (800–1500 μl l−1) on whole plants grown in air at 400μmol m−2 s−1 irradiance was significantly increased in the high SPS expressors compared to the untransformed controls and was highest where SPS activity was greatest. At high CO2 the stimulation of photosynthesis was more pronounced. We conclude that SPS activity is a major point of control of photosynthesis particularly under saturating light and CO2.
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Claims 7
Claim · model-written summary
High-SPS tomato plants increased sucrose synthesis relative to starch.
- Taxon
- tomato
Solanum lycopersicumt0 - Gene
- sucrose phosphate synthaset1
- Outcome
- rate of sucrose synthesise0
- Direction
- increasede0
- Comparator
- starche0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The rate of sucrose synthesis was increased relative to that of starch”
t0“tomato (Lycopersicon esculentum L.)”
t1“sucrose phosphate synthase”
Claim · model-written summary
High-SPS tomato leaves had higher sucrose to starch ratios throughout the photoperiod.
- Taxon
- tomatoSolanum lycopersicumt0
- Organ / stage
- leavese0
- Outcome
- sucrose/starch ratiose0
- Direction
- highere0
- Qualifier
- throughout the photoperiode0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“sucrose/starch ratios were higher throughout the photoperiod in the leaves of all plants expressing high SPS activity”
t0“tomato (Lycopersicon esculentum L.)”
Claim · model-written summary
Leaf carbon budgets under low irradiance were similar in all tomato plants.
- Taxon
- tomatoSolanum lycopersicumt0
- Outcome
- leaf carbon budgete0
- Direction
- similare0
- Qualifier
- low irradiance (180μmol photon m−2 s−1)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The leaf carbon budget over the day/night cycle in air at low irradiance (180μmol photon m−2 s−1) was similar in all plants.”
t0“tomato (Lycopersicon esculentum L.)”
Claim · model-written summary
Net photosynthesis in air and elevated CO2 was significantly higher in high-SPS expressors than untransformed controls.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- high SPS expressorse0
- Outcome
- Net photosynthesise0
- Direction
- increasede0
- Qualifier
- elevated CO2 (800–1500 μl l−1)e0
- Comparator
- untransformed controlse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Net photosynthesis measured in air and at elevated CO2 (800–1500 μl l−1) on whole plants grown in air at 400μmol m−2 s−1 irradiance was significantly increased in the high SPS expressors compared to the untransformed controls”
t0“tomato (Lycopersicon esculentum L.)”
Claim · model-written summary
Net photosynthesis was highest where SPS activity was greatest.
- Taxon
- tomatoSolanum lycopersicumt0
- Gene
- SPSe0
- Outcome
- Net photosynthesise1
- Direction
- higheste0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“was highest where SPS activity was greatest”
e1“Net photosynthesis measured in air and at elevated CO2”
t0“tomato (Lycopersicon esculentum L.)”
Claim · model-written summary
Elevated CO2 made the stimulation of photosynthesis more pronounced.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- high CO2e0
- Outcome
- stimulation of photosynthesise0
- Direction
- more pronouncede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At high CO2 the stimulation of photosynthesis was more pronounced.”
t0“tomato (Lycopersicon esculentum L.)”
Claim · model-written summary
The authors conclude that SPS activity controls photosynthesis especially under saturating light and CO2.
- Taxon
- tomatoSolanum lycopersicumt0
- Gene
- SPSe0
- Outcome
- photosynthesise0
- Qualifier
- under saturating light and CO2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“SPS activity is a major point of control of photosynthesis particularly under saturating light and CO2”
t0“tomato (Lycopersicon esculentum L.)”
The same questions in other papers
co2 · physiology: photosynthesis · Solanum lycopersicum (tomato)Results differ
30 papers in the same direction as this paper · 6 in the opposite direction · 2 reporting no difference from an alternative
- no effect
- no effect
- no effect
35 papers more in this group
See all 39 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.