Abstract
Sugar Beets (Beta vulgaris L. cv F58-554H1) were cultured hydroponically in growth chambers. Leaf orthophosphate (Pi) levels were varied nutritionally. The effect of decreased leaf phosphate (low-P) status was determined on the diurnal changes in the pool sizes of leaf ribulose 1,5-bisphosphate (RuBP), 3-phosphoglycerate (PGA), triose phosphate, fructose 1,6-bisphosphate, fructose-6-phosphate, glucose-6-phosphate, adenylates, nicotinamide nucleotides, and Pi. Except for triose phosphate, low-P treatment caused a marked reduction in the levels of leaf sugar phosphates (on a leaf area basis) throughout the diurnal cycle. Low-P treatment decreased the average leaf RuBP levels by 60 to 69% of control values during the light period. Low-P increased NADPH levels and NADPH/NADP(+) ratio but decreased ATP; the ATP/ADP ratio was unaffected. Low P treatment caused a marked reduction in RuBP regeneration (RuBP levels were half the RuBP carboxylase binding site concentration) but did not depress PGA reduction to triose phosphate. These results indicate that photosynthesis in low-P leaves was limited by RuBP regeneration and that RuBP formation in low-P leaves was not limited by the supply of ATP and NADPH. We suggest that RuBP regeneration was limited by the supply of fixed carbon, an increased proportion of which was diverted to starch synthesis.
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Claims 12
Claim · model-written summary
Low leaf phosphate status markedly reduced leaf sugar phosphate levels (per leaf area) throughout the diurnal cycle in sugar beet.
- Taxon
- Sugar Beet
Beta vulgaris subsp. vulgarist0 - Treatment
- low-P treatmente0
- Outcome
- levels of leaf sugar phosphatese0
- Direction
- reductione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Sugar Beet”
e0“low-P treatment caused a marked reduction in the levels of leaf sugar phosphates (on a leaf area basis) throughout the diurnal cycle”
Claim · model-written summary
Triose phosphate was the exception: its level was not reduced by low-P treatment.
- Taxon
- Sugar BeetBeta vulgaris subsp. vulgarist0
- Treatment
- low-P treatmente0
- Outcome
- triose phosphatee0
- Direction
- no_changeinferrede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Sugar Beet”
e0“Except for triose phosphate, low-P treatment”
Claim · model-written summary
Low-P treatment decreased average leaf RuBP levels by 60 to 69% of control values during the light period.
- Taxon
- Sugar BeetBeta vulgaris subsp. vulgarist0
- Treatment
- Low-P treatmente0
- Outcome
- average leaf RuBP levelse0
- Direction
- decreasede0
- Value
- 60 to 69%e0
- Comparator
- controle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Sugar Beet”
e0“Low-P treatment decreased the average leaf RuBP levels by 60 to 69% of control values during the light period”
Claim · model-written summary
Low-P increased NADPH levels and the NADPH/NADP+ ratio.
- Taxon
- Sugar BeetBeta vulgaris subsp. vulgarist0
- Treatment
- Low-Pe0
- Outcome
- NADPH levels and NADPH/NADP(+) ratioe0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Sugar Beet”
e0“Low-P increased NADPH levels and NADPH/NADP(+) ratio but decreased ATP; the ATP/ADP ratio was unaffected”
Claim · model-written summary
Low-P decreased ATP levels.
- Taxon
- Sugar BeetBeta vulgaris subsp. vulgarist0
- Treatment
- Low-Pe0
- Outcome
- ATPe0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Sugar Beet”
e0“Low-P increased NADPH levels and NADPH/NADP(+) ratio but decreased ATP; the ATP/ADP ratio was unaffected”
Claim · model-written summary
The ATP/ADP ratio was unaffected by low-P.
- Taxon
- Sugar BeetBeta vulgaris subsp. vulgarist0
- Treatment
- Low-Pe0
- Outcome
- ATP/ADP ratioe0
- Direction
- unaffectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Sugar Beet”
e0“Low-P increased NADPH levels and NADPH/NADP(+) ratio but decreased ATP; the ATP/ADP ratio was unaffected”
Claim · model-written summary
Low P treatment caused a marked reduction in RuBP regeneration.
- Taxon
- Sugar BeetBeta vulgaris subsp. vulgarist0
- Treatment
- Low P treatmente0
- Outcome
- RuBP regeneratione0
- Direction
- reductione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Sugar Beet”
e0“Low P treatment caused a marked reduction in RuBP regeneration”
Claim · model-written summary
Under low P, RuBP levels were half the RuBP carboxylase binding site concentration.
- Taxon
- Sugar BeetBeta vulgaris subsp. vulgarist0
- Outcome
- RuBP levelse0
- Value
- half the RuBP carboxylase binding site concentratione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Sugar Beet”
e0“RuBP levels were half the RuBP carboxylase binding site concentration”
Claim · model-written summary
Low P treatment did not depress PGA reduction to triose phosphate.
- Taxon
- Sugar BeetBeta vulgaris subsp. vulgarist0
- Treatment
- Low P treatmente0
- Outcome
- PGA reduction to triose phosphatee0
- Direction
- did not depresse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Sugar Beet”
e0“Low P treatment caused a marked reduction in RuBP regeneration (RuBP levels were half the RuBP carboxylase binding site concentration) but did not depress PGA reduction to triose phosphate”
Claim · model-written summary
The authors conclude that photosynthesis in low-P leaves was limited by RuBP regeneration.
- Taxon
- Sugar BeetBeta vulgaris subsp. vulgarist0
- Treatment
- low-Pe0
- Outcome
- photosynthesise0
- Qualifier
- limited by RuBP regeneratione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Sugar Beet”
e0“photosynthesis in low-P leaves was limited by RuBP regeneration”
Claim · model-written summary
The authors conclude that RuBP formation in low-P leaves was not limited by the supply of ATP and NADPH.
- Taxon
- Sugar BeetBeta vulgaris subsp. vulgarist0
- Compound
- ATP and NADPHe0
- Outcome
- RuBP formatione0
- Qualifier
- not limitede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Sugar Beet”
e0“RuBP formation in low-P leaves was not limited by the supply of ATP and NADPH”
Claim · model-written summary
The authors suggest that RuBP regeneration was limited by the supply of fixed carbon, an increased proportion of which was diverted to starch synthesis.
- Taxon
- Sugar BeetBeta vulgaris subsp. vulgarist0
- Outcome
- RuBP regeneratione0
- Qualifier
- limited by the supply of fixed carbone0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Sugar Beet”
e0“RuBP regeneration was limited by the supply of fixed carbon, an increased proportion of which was diverted to starch synthesis”
The same questions in other papers
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See all 23 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.