Abstract
The effects of low concentrations of phosphate (low-P) on soluble protein content, the activities of 12 different enzymes, and the rates of photosynthesis and respiration on the basis of leaf area were investigated in maize (Zea mays L.) leaves 16 to 24 days after planting (DAP). With low-P treatment, a drastic decrease in the rate of photosynthesis to only 6% of the maximum rate in control plants was observed by 24 DAP. Low-P treatment had almost no effect on the rate of respiration until 21 DAP, but then the rate of respiration decreased progressively to about 55% of the maximum rate in control plants. The soluble protein content in low-P plants decreased to 56% of the maximum content in control plants. The changes in the activities of enzymes in low-P plants showed several different patterns. The activities of pyruvate, orthophosphate dikinase, 3-phosphoglycerate kinase, phosphoenolpyruvate carboxylase (PEPC), ribulose 1,5-bisphosphate carboxylase, fructose 1,6-bisphosphate aldolase, catalase, phosphohexose isomerase, chloroplastic fructose 1,6-bisphosphatase, and ADP-glucose-pyrophosphorylase decreased steadily from 85 to 100% of the maximum activity found in 18- to 21-day-old control plants (V(max)) to 30 to 70% of V(max). The activity of sucrose phosphate synthase remained virtually constant at approximately 85 to 100% of V(max). The activity of UDP-glucose-pyrophosphorylase remained almost constant up to 21 DAP and then decreased to 80% of V(max) by 24 DAP. The activity of cytochrome c oxidase increased slightly up to 21 DAP but then decreased to 50% of V(max) by 24 DAP. As indicated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of soluble proteins, the subunit of PEPC stained less intensely in 24-d-old low-P plants. The possibility is discussed that during low-P treatment there is selective degradation of PEPC without a concomitant degradation of sucrose phosphate synthase, both of which are known to be localized in the cytoplasmic compartment of mesophyll cells.
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Claims 11
Claim · model-written summary
Low phosphate reduced maize leaf photosynthesis to 6% of the control maximum by 24 days after planting.
- Organ / stage
- leavese0
- Treatment
- low-P treatmente1
- Outcome
- rate of photosynthesise1
- Direction
- decreasee1
- Value
- 6%e1
- Qualifier
- 24 DAPe1
- Comparator
- control plantse1
Zea maysOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“maize (Zea mays L.) leaves”
e1“With low-P treatment, a drastic decrease in the rate of photosynthesis to only 6% of the maximum rate in control plants was observed by 24 DAP.”
Claim · model-written summary
Low phosphate had almost no effect on maize respiration until 21 days after planting.
- Treatment
- Low-P treatmente1
- Outcome
- rate of respiratione1
- Direction
- almost no effecte1
- Qualifier
- until 21 DAPe1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“maize (Zea mays L.) leaves”
e1“Low-P treatment had almost no effect on the rate of respiration until 21 DAP”
Claim · model-written summary
After 21 days, low phosphate progressively reduced maize respiration to about 55% of the control maximum.
- Outcome
- rate of respiratione1
- Direction
- decreased progressivelye1
- Value
- about 55%e1
- Comparator
- control plantse1
Not reportedTreatment
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“maize (Zea mays L.) leaves”
e1“but then the rate of respiration decreased progressively to about 55% of the maximum rate in control plants.”
Claim · model-written summary
Soluble protein content in low phosphate maize fell to 56% of the control maximum.
- Treatment
- low-Pe1
- Outcome
- soluble protein contente1
- Direction
- decreasede1
- Value
- 56%e1
- Comparator
- control plantse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“maize (Zea mays L.) leaves”
e1“The soluble protein content in low-P plants decreased to 56% of the maximum content in control plants.”
Claim · model-written summary
Activities of ten listed enzymes decreased from 85–100% to 30–70% of control maximum under low phosphate.
- Outcome
- activitiese1
- Direction
- decreased steadilye1
- Value
- 30 to 70% of V(max)e1
- Comparator
- 18- to 21-day-old control plantse1
Not reportedTreatment
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“maize (Zea mays L.) leaves”
e1“The activities of pyruvate, orthophosphate dikinase, 3-phosphoglycerate kinase, phosphoenolpyruvate carboxylase (PEPC), ribulose 1,5-bisphosphate carboxylase, fructose 1,6-bisphosphate aldolase, catalase, phosphohexose isomerase, chloroplastic fructose 1,6-bisphosphatase, and ADP-glucose-pyrophosphorylase decreased steadily from 85 to 100% of the maximum activity found in 18- to 21-day-old control plants (V(max)) to 30 to 70% of V(max).”
Claim · model-written summary
Sucrose phosphate synthase activity remained nearly constant at 85–100% of Vmax.
- Gene
- sucrose phosphate synthasee1
- Outcome
- activity of sucrose phosphate synthasee1
- Direction
- remained virtually constante1
- Value
- approximately 85 to 100% of V(max)e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“maize (Zea mays L.) leaves”
e1“The activity of sucrose phosphate synthase remained virtually constant at approximately 85 to 100% of V(max).”
Claim · model-written summary
UDP-glucose-pyrophosphorylase activity stayed almost constant through 21 days after planting.
- Gene
- UDP-glucose-pyrophosphorylasee1
- Outcome
- activity of UDP-glucose-pyrophosphorylasee1
- Direction
- remained almost constante1
- Qualifier
- up to 21 DAPe1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“maize (Zea mays L.) leaves”
e1“The activity of UDP-glucose-pyrophosphorylase remained almost constant up to 21 DAP”
Claim · model-written summary
UDP-glucose-pyrophosphorylase activity then decreased to 80% of Vmax by day 24.
- Gene
- UDP-glucose-pyrophosphorylasee1
- Outcome
- activity of UDP-glucose-pyrophosphorylasee1
- Direction
- decreasede1
- Value
- 80% of V(max)e1
- Qualifier
- 24 DAPe1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“maize (Zea mays L.) leaves”
e1“The activity of UDP-glucose-pyrophosphorylase remained almost constant up to 21 DAP and then decreased to 80% of V(max) by 24 DAP.”
Claim · model-written summary
Cytochrome c oxidase activity increased slightly until day 21.
- Gene
- cytochrome c oxidasee1
- Outcome
- activity of cytochrome c oxidasee1
- Direction
- increased slightlye1
- Qualifier
- up to 21 DAPe1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“maize (Zea mays L.) leaves”
e1“The activity of cytochrome c oxidase increased slightly up to 21 DAP”
Claim · model-written summary
Cytochrome c oxidase activity then decreased to 50% of Vmax by day 24.
- Gene
- cytochrome c oxidasee1
- Outcome
- activity of cytochrome c oxidasee1
- Direction
- decreasede1
- Value
- 50% of V(max)e1
- Qualifier
- 24 DAPe1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“maize (Zea mays L.) leaves”
e1“The activity of cytochrome c oxidase increased slightly up to 21 DAP but then decreased to 50% of V(max) by 24 DAP.”
Claim · model-written summary
PEPC protein subunit stained less intensely in 24-day-old low phosphate maize.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“maize (Zea mays L.) leaves”
e1“the subunit of PEPC stained less intensely in 24-d-old low-P plants.”
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See all 27 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.