Abstract
SUMMARY Rice (Oryza sativa L.) is grown in many different agro-ecological zones and it assimilates CO2 directly through C3 photosynthesis. At current CO2 partial pressure [p(CO2)], rice is not photosynthetically saturated but immediately after exposure to 100 p(CO2), photosynthetic rates are increased by 48 percent on an average. However, this increase is not sustained during prolonged exposure and is associated with reduced amounts of ribulose-1-5-bisphospate carboxylase/oxygenase (Rubisco) content and its maximum potential activity (Vcmax). Rubisco content and Vcmax were reduced by 33 and 22%, respectively, at elevated p(CO2) and this has an additive effect on leaf photosynthesis. Activation state of the Rubisco is also decreased by elevated p(CO2) but no deactivation of Rubisco occurs in rbc S antisense rice with 40% wild type Rubisco suggesting that deactivation is an optimize response. Large amounts of Rubisco (about 80–90%) is synthesized prior to full expansion of leaf when sugar accumulation is minimal. After the leaf has fully expanded, very little Rubisco (about 10-20%) is synthesized and a large amount of sugar accumulates during this period. Therefore, it is unlikely that downregulation of Rubisco at elevated p(CO2) is caused by decreasing the mRNA transcripts for Rubisco small subunit (rbcS) and Rubisco large subunit (rbcL) through soluble sugars. It is more likely that elevated p(CO2) mediated decline in Rubisco is due to rapid degradation of protein and lower nitrogen (N) allocation to Rubisco due to reduced N afflux. Leaf N content was reduced by 16% in plants grown at elevated p(CO2) though leaf N to Rubisco ratio remained consistently unchanged regardless of growth p(CO2) suggesting that N assimilation, distribution and remobilization at the whole plant level is tightly controlled at elevated p(CO2). Further, changes in N and C metabolisms at elevated p(CO2) are likely to reduce the critical N concentration by 30% at elevated p(CO2).
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Claims 15
Claim · model-written summary
Immediately after exposure to 100 p(CO2), rice photosynthetic rates increased by 48% on average relative to current CO2.
- Taxon
- rice
Oryza sativae1 - Treatment
- exposure to 100 p(CO2)e1
- Outcome
- photosynthetic ratese1
- Direction
- increasede1
- Value
- 48 percente1
- Comparator
- At current CO2 partial pressuree1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“At current CO2 partial pressure [p(CO2)], rice is not photosynthetically saturated but immediately after exposure to 100 p(CO2), photosynthetic rates are increased by 48 percent on an average”
Claim · model-written summary
The rice photosynthetic increase under elevated CO2 was not sustained during prolonged exposure.
- Taxon
- riceOryza sativae1
- Treatment
- prolonged exposuree2
- Outcome
- this increasee2
- Direction
- not sustainede2
- Comparator
- immediately after exposuree1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“At current CO2 partial pressure [p(CO2)], rice is not photosynthetically saturated but immediately after exposure to 100 p(CO2), photosynthetic rates are increased by 48 percent on an average”
e2“this increase is not sustained during prolonged exposure”
Claim · model-written summary
Elevated CO2 reduced rice Rubisco content by 33%.
- Taxon
- riceOryza sativae1
- Treatment
- elevated p(CO2)e3
- Outcome
- Rubisco contente3
- Direction
- reducede3
- Value
- 33e3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“At current CO2 partial pressure [p(CO2)], rice is not photosynthetically saturated but immediately after exposure to 100 p(CO2), photosynthetic rates are increased by 48 percent on an average”
e3“Rubisco content and Vcmax were reduced by 33 and 22%, respectively, at elevated p(CO2)”
Claim · model-written summary
Elevated CO2 reduced rice Vcmax by 22%.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“At current CO2 partial pressure [p(CO2)], rice is not photosynthetically saturated but immediately after exposure to 100 p(CO2), photosynthetic rates are increased by 48 percent on an average”
e3“Rubisco content and Vcmax were reduced by 33 and 22%, respectively, at elevated p(CO2)”
Claim · model-written summary
Elevated CO2 decreased the activation state of Rubisco in rice.
- Taxon
- riceOryza sativae1
- Treatment
- elevated p(CO2)e4
- Outcome
- Activation state of the Rubiscoe4
- Direction
- decreasede4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“At current CO2 partial pressure [p(CO2)], rice is not photosynthetically saturated but immediately after exposure to 100 p(CO2), photosynthetic rates are increased by 48 percent on an average”
e4“Activation state of the Rubisco is also decreased by elevated p(CO2)”
Claim · model-written summary
Rubisco deactivation is an optimized response, suggested by the absence of deactivation in rbcS antisense rice with 40% wild-type Rubisco.
- Taxon
- riceOryza sativae1
- Material
- rbc S antisense ricee5
- Gene
- rbc Se5
- Outcome
- deactivation is an optimize responsee5
- Qualifier
- 40% wild type Rubiscoe5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“At current CO2 partial pressure [p(CO2)], rice is not photosynthetically saturated but immediately after exposure to 100 p(CO2), photosynthetic rates are increased by 48 percent on an average”
e5“no deactivation of Rubisco occurs in rbc S antisense rice with 40% wild type Rubisco suggesting that deactivation is an optimize response”
Claim · model-written summary
Large amounts of Rubisco (about 80–90%) are synthesized before full leaf expansion, when sugar accumulation is minimal.
- Taxon
- riceOryza sativae1
- Organ / stage
- leafe6
- Outcome
- Large amounts of Rubiscoe6
- Value
- about 80–90%e6
- Qualifier
- when sugar accumulation is minimale6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“At current CO2 partial pressure [p(CO2)], rice is not photosynthetically saturated but immediately after exposure to 100 p(CO2), photosynthetic rates are increased by 48 percent on an average”
e6“Large amounts of Rubisco (about 80–90%) is synthesized prior to full expansion of leaf when sugar accumulation is minimal”
Claim · model-written summary
After the leaf has fully expanded, very little Rubisco (about 10-20%) is synthesized in rice.
- Taxon
- riceOryza sativae1
- Organ / stage
- leafe7
- Outcome
- very little Rubiscoe7
- Value
- about 10-20%e7
- Qualifier
- After the leaf has fully expandede7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“At current CO2 partial pressure [p(CO2)], rice is not photosynthetically saturated but immediately after exposure to 100 p(CO2), photosynthetic rates are increased by 48 percent on an average”
e7“After the leaf has fully expanded, very little Rubisco (about 10-20%) is synthesized and a large amount of sugar accumulates during this period”
Claim · model-written summary
After the leaf has fully expanded, a large amount of sugar accumulates in rice leaves.
- Taxon
- riceOryza sativae1
- Organ / stage
- leafe7
- Outcome
- a large amount of sugar accumulatese7
- Qualifier
- After the leaf has fully expandede7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“At current CO2 partial pressure [p(CO2)], rice is not photosynthetically saturated but immediately after exposure to 100 p(CO2), photosynthetic rates are increased by 48 percent on an average”
e7“After the leaf has fully expanded, very little Rubisco (about 10-20%) is synthesized and a large amount of sugar accumulates during this period”
Claim · model-written summary
Rubisco downregulation at elevated CO2 is unlikely to be caused by decreased rbcS and rbcL mRNA transcripts through soluble sugars.
- Taxon
- riceOryza sativae1
- Gene
- rbcSe2
- Compound
- soluble sugarse2
- Outcome
- downregulation of Rubiscoe2
- Qualifier
- unlikelye2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“At current CO2 partial pressure [p(CO2)], rice is not photosynthetically saturated but immediately after exposure to 100 p(CO2), photosynthetic rates are increased by 48 percent on an average”
e2“Therefore, it is unlikely that downregulation of Rubisco at elevated p(CO2) is caused by decreasing the mRNA transcripts for Rubisco small subunit (rbcS) and Rubisco large subunit (rbcL) through soluble sugars”
Claim · model-written summary
Elevated CO2 decline in Rubisco is more likely due to rapid protein degradation and lower N allocation to Rubisco.
- Taxon
- riceOryza sativae1
- Treatment
- elevated p(CO2)e2
- Outcome
- decline in Rubiscoe2
- Qualifier
- rapid degradation of proteine2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“At current CO2 partial pressure [p(CO2)], rice is not photosynthetically saturated but immediately after exposure to 100 p(CO2), photosynthetic rates are increased by 48 percent on an average”
e2“It is more likely that elevated p(CO2) mediated decline in Rubisco is due to rapid degradation of protein and lower nitrogen (N) allocation to Rubisco due to reduced N afflux”
Claim · model-written summary
Leaf N content was reduced by 16% in rice grown at elevated CO2.
- Taxon
- riceOryza sativae1
- Treatment
- elevated p(CO2)e2
- Outcome
- Leaf N contente2
- Direction
- reducede2
- Value
- 16%e2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“At current CO2 partial pressure [p(CO2)], rice is not photosynthetically saturated but immediately after exposure to 100 p(CO2), photosynthetic rates are increased by 48 percent on an average”
e2“Leaf N content was reduced by 16% in plants grown at elevated p(CO2)”
Claim · model-written summary
The leaf N to Rubisco ratio stayed unchanged regardless of growth CO2.
- Taxon
- riceOryza sativae1
- Treatment
- growth p(CO2)e2
- Outcome
- leaf N to Rubisco ratioe2
- Direction
- unchangede2
- Qualifier
- consistently unchangede2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“At current CO2 partial pressure [p(CO2)], rice is not photosynthetically saturated but immediately after exposure to 100 p(CO2), photosynthetic rates are increased by 48 percent on an average”
e2“leaf N to Rubisco ratio remained consistently unchanged regardless of growth p(CO2)”
Claim · model-written summary
N assimilation, distribution and remobilization at whole-plant level appear tightly controlled at elevated CO2.
- Taxon
- riceOryza sativae1
- Treatment
- elevated p(CO2)e2
- Outcome
- N assimilation, distribution and remobilization at the whole plant levele2
- Qualifier
- tightly controllede2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“At current CO2 partial pressure [p(CO2)], rice is not photosynthetically saturated but immediately after exposure to 100 p(CO2), photosynthetic rates are increased by 48 percent on an average”
e2“suggesting that N assimilation, distribution and remobilization at the whole plant level is tightly controlled at elevated p(CO2)”
Claim · model-written summary
Changes in N and C metabolism at elevated CO2 are likely to reduce the critical N concentration by 30%.
- Taxon
- riceOryza sativae1
- Treatment
- elevated p(CO2)e2
- Outcome
- critical N concentratione2
- Direction
- reducee2
- Value
- 30%e2
- Qualifier
- likelye2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“At current CO2 partial pressure [p(CO2)], rice is not photosynthetically saturated but immediately after exposure to 100 p(CO2), photosynthetic rates are increased by 48 percent on an average”
e2“changes in N and C metabolisms at elevated p(CO2) are likely to reduce the critical N concentration by 30% at elevated p(CO2)”
The same questions in other papers
co2 · physiology: photosynthesis · Oryza sativa (rice)Results differ
44 papers in the same direction as this paper · 16 in the opposite direction · 1 reporting no difference from an alternative
- negative
- positive
- negative
58 papers more in this group
See all 62 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.