Abstract
Untransformed maize and tobacco plants and tobacco plants constitutively expressing nitrate reductase were grown with sufficient NO(3)- to support maximal growth. Four days prior to treatment the tobacco plants were deprived of nitrogen. Excised maize leaves and tobacco leaf discs were fed with either 40 mM KNO(3) or 40 mM KCl (control) in the light. Phosphoenolpyruvate (PEP) carboxylase (Case) activity was measured at 0.3 mM and 3 mM PEP. The light- induced increase in PEPCase V(max) was greater in maize than tobacco. Furthermore light decreased malate sensitivity in maize (which was N-replete) but not in N-deficient tobacco. NO(3)- treatment increased PEPCase V:(max) values in both species and decreased the sensitivity to inhibition by malate, but effects of NO(3)- were much more pronounced in tobacco than maize. PEPCase kinase activity was, however, greater in maize leaves NO(3)- than in the Cl(-)-treated controls, suggesting that it is responsive to leaf nitrogen supply. A correlation between foliar glutamine content and PEPCase activity was observed. It is concluded that PEPCase is sensitive to N metabolites which favour increased flow through the anapleurotic pathway in both C(3) and C(4) plants.
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Claims 9
Claim · model-written summary
Light increased PEPCase V(max) more in maize than tobacco.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The light- induced increase in PEPCase V(max) was greater in maize than tobacco.”
Claim · model-written summary
Light decreased malate sensitivity in nitrogen-replete maize.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“light decreased malate sensitivity in maize (which was N-replete) but not in N-deficient tobacco.”
Claim · model-written summary
Light did not decrease malate sensitivity in nitrogen-deficient tobacco.
- Taxon
- tobacco
Nicotiana tabacume0 - Treatment
- lighte0
- Outcome
- malate sensitivitye0
- Direction
- note0
- Qualifier
- N-deficiente0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“light decreased malate sensitivity in maize (which was N-replete) but not in N-deficient tobacco.”
Claim · model-written summary
Nitrate increased PEPCase V(max) in maize.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“NO(3)- treatment increased PEPCase V:(max) values in both species”
t0“tobacco and maize leaves”
Claim · model-written summary
Nitrate increased PEPCase V(max) in tobacco.
- Taxon
- tobaccoNicotiana tabacumt0
- Treatment
- NO(3)- treatmente0
- Outcome
- PEPCase V:(max)e0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“NO(3)- treatment increased PEPCase V:(max) values in both species”
t0“tobacco and maize leaves”
Claim · model-written summary
Nitrate decreased sensitivity to malate inhibition in both species, more strongly in tobacco.
- Taxon
- tobaccoNicotiana tabacumt0
- Treatment
- NO(3)-e0
- Outcome
- sensitivity to inhibition by malatee0
- Direction
- decreasede0
- Comparator
- maizee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“decreased the sensitivity to inhibition by malate, but effects of NO(3)- were much more pronounced in tobacco than maize.”
t0“tobacco and maize leaves”
Claim · model-written summary
Nitrate-treated maize leaves had greater PEPCase kinase activity than chloride controls.
- Treatment
- NO(3)-e0
- Outcome
- PEPCase kinase activitye0
- Direction
- greatere0
- Comparator
- Cl(-)-treated controlse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“PEPCase kinase activity was, however, greater in maize leaves NO(3)- than in the Cl(-)-treated controls”
Claim · model-written summary
Foliar glutamine content correlated with PEPCase activity.
- Taxon
- tobacco and maizeNicotiana tabacum
Zea mayst0 - Organ / stage
- foliare0
- Compound
- glutaminee0
- Outcome
- PEPCase activitye0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A correlation between foliar glutamine content and PEPCase activity was observed.”
t0“tobacco and maize leaves”
Claim · model-written summary
The authors conclude that nitrogen metabolites increase flow through the anapleurotic pathway via PEPCase sensitivity.
Verbatim
e0“PEPCase is sensitive to N metabolites which favour increased flow through the anapleurotic pathway in both C(3) and C(4) plants.”
The same questions in other papers
light · molecular: metabolites · Nicotiana tabacum (tobacco)Positive and negative results
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See all 21 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.