Abstract
We have examined the possible role of leaf cytosolic hexoses and the expression of mannitol metabolism as mechanisms that may affect the repression of photosynthetic capacity when plants are grown at 1000 versus 380 [mu]L L-1 CO2. In plants grown at high CO2, leaf ribulose-1,5-bisphosphate carboxylase/oxygenase content declined by [greater than or equal to]20% in tobacco (Nicotiana sylvestris) but was not affected in the mannitol-producing species snapdragon (Antirrhinum majus) and parsley (Petroselinum hortense). In the three species mesophyll glucose and fructose at midday occurred almost entirely in the vacuole (>99%), irrespective of growth CO2 levels. The estimated cytosolic concentrations of glucose and fructose were [less than or equal to]100 [mu]M. In the three species grown at high CO2, total leaf carbohydrates increased 60 to 100%, but mannitol metabolism did not function as an overflow mechanism for the increased accumulation of carbohydrate. In both snapdragon and parsley grown at ambient or high CO2, mannitol occurred in the chloroplast and cytosol at estimated midday concentrations of 0.1 M or more each. The compartmentation of leaf hexoses and the metabolism of alternate carbohydrates are further considered in relation to photosynthetic acclimation to high levels of CO2.
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Claims 9
Claim · model-written summary
High CO2 reduced tobacco leaf Rubisco content by at least 20%.
- Taxon
- tobacco
Nicotiana tabacume0 - Treatment
- High CO2t0
- Gene
- ribulose-1,5-bisphosphate carboxylase/oxygenasee0
- Outcome
- leaf ribulose-1,5-bisphosphate carboxylase/oxygenase contente0
- Direction
- declinede0
- Value
- [greater than or equal to]20%e0
- Comparator
- 380 [mu]L L-1 CO2e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“leaf ribulose-1,5-bisphosphate carboxylase/oxygenase content declined by [greater than or equal to]20% in tobacco (Nicotiana sylvestris)”
e1“1000 versus 380 [mu]L L-1 CO2”
t0“High CO2 Concentrations”
Claim · model-written summary
High CO2 did not affect snapdragon Rubisco content.
- Taxon
- snapdragon
Antirrhinum majuse0 - Treatment
- High CO2t0
- Outcome
- ribulose-1,5-bisphosphate carboxylase/oxygenase contente2
- Direction
- not affectede0
- Comparator
- 380 [mu]L L-1 CO2e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“was not affected in the mannitol-producing species snapdragon (Antirrhinum majus) and parsley (Petroselinum hortense)”
e1“1000 versus 380 [mu]L L-1 CO2”
e2“leaf ribulose-1,5-bisphosphate carboxylase/oxygenase content”
t0“High CO2 Concentrations”
Claim · model-written summary
High CO2 did not affect parsley Rubisco content.
- Taxon
- parsley
Petroselinum crispume0 - Treatment
- High CO2t0
- Outcome
- ribulose-1,5-bisphosphate carboxylase/oxygenase contente2
- Direction
- not affectede0
- Comparator
- 380 [mu]L L-1 CO2e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“was not affected in the mannitol-producing species snapdragon (Antirrhinum majus) and parsley (Petroselinum hortense)”
e1“1000 versus 380 [mu]L L-1 CO2”
e2“leaf ribulose-1,5-bisphosphate carboxylase/oxygenase content”
t0“High CO2 Concentrations”
Claim · model-written summary
In all three species, over 99% of mesophyll glucose and fructose was vacuolar regardless of CO2.
- Taxon
- Tobacco, Snapdragon, and ParsleyPetroselinum crispumNicotiana tabacumAntirrhinum majust0
- Outcome
- mesophyll glucose and fructose at midday occurred almost entirely in the vacuolee0
- Value
- >99%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In the three species mesophyll glucose and fructose at midday occurred almost entirely in the vacuole (>99%), irrespective of growth CO2 levels.”
t0“Tobacco, Snapdragon, and Parsley”
Claim · model-written summary
Estimated cytosolic glucose and fructose concentrations were at most 100 micromolar.
- Taxon
- Tobacco, Snapdragon, and ParsleyPetroselinum crispumNicotiana tabacumAntirrhinum majust0
- Outcome
- cytosolic concentrations of glucose and fructosee0
- Value
- [less than or equal to]100 [mu]Me0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The estimated cytosolic concentrations of glucose and fructose were [less than or equal to]100 [mu]M.”
t0“Tobacco, Snapdragon, and Parsley”
Claim · model-written summary
High CO2 increased total leaf carbohydrates by 60 to 100% in the three species.
- Taxon
- Tobacco, Snapdragon, and ParsleyPetroselinum crispumNicotiana tabacumAntirrhinum majust0
- Treatment
- high CO2e0
- Outcome
- total leaf carbohydratese0
- Direction
- increasede0
- Value
- 60 to 100%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In the three species grown at high CO2, total leaf carbohydrates increased 60 to 100%”
t0“Tobacco, Snapdragon, and Parsley”
Claim · model-written summary
Mannitol metabolism did not serve as an overflow mechanism for increased carbohydrate accumulation.
- Taxon
- Tobacco, Snapdragon, and ParsleyPetroselinum crispumNicotiana tabacumAntirrhinum majust0
- Outcome
- increased accumulation of carbohydratee0
- Qualifier
- mannitol metabolism did not function as an overflow mechanisme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“mannitol metabolism did not function as an overflow mechanism for the increased accumulation of carbohydrate”
t0“Tobacco, Snapdragon, and Parsley”
Claim · model-written summary
Snapdragon had mannitol in chloroplast and cytosol at at least 0.1 M each under both CO2 levels.
- Taxon
- snapdragonAntirrhinum majuse0
- Outcome
- mannitol occurred in the chloroplast and cytosole0
- Value
- 0.1 M or more eache0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In both snapdragon and parsley grown at ambient or high CO2, mannitol occurred in the chloroplast and cytosol at estimated midday concentrations of 0.1 M or more each.”
Claim · model-written summary
Parsley had mannitol in chloroplast and cytosol at at least 0.1 M each under both CO2 levels.
- Taxon
- parsleyPetroselinum crispume0
- Outcome
- mannitol occurred in the chloroplast and cytosole0
- Value
- 0.1 M or more eache0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In both snapdragon and parsley grown at ambient or high CO2, mannitol occurred in the chloroplast and cytosol at estimated midday concentrations of 0.1 M or more each.”
The same questions in other papers
co2 · molecular: metabolites · Nicotiana tabacum (tobacco)Results differ
5 papers in the same direction as this paper · 4 in the opposite direction
- no effect
- positive
- positive
6 papers more in this group
See all 10 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.