Abstract
Characterization of the effects of long-term P deficiency and of onset and recovery from P deficiency on bacteroid mass and number per unit nodule mass and energy status of soybean (Glycine max L. Merr.) nodules was used to investigate the mechanisms by which P deficiency decreases symbiotic N(2) fixation. The continuous P deficiency treatment (0.05 millimolar P) significantly decreased the whole plant dry mass, P, and N by 62, 90, and 78%, respectively, relative to the P-sufficient control (1.0 millimolar) at 44 days after transplanting. Specific nitrogenase activity was decreased an average of 28% over a 16-day experimental period by P deficiency. Whole nodules of P-deficient controls contained 70 to 75% lower ATP concentrations than nodules of P-sufficient controls. Energy charge and ATP concentrations in the bacteroid fraction of nodules were not significantly affected by P treatment. However, ATP and total adenylate concentrations and energy charge in the plant cell fraction of nodules were significantly decreased 91, 62, and 50%, respectively, by the P deficiency treatment. Specific nitrogenase activity, energy charge, and ATP concentration in the plant cell fraction increased to the levels of nonstressed controls within 2, 2, and 4 days, respectively, after alleviation of external P limitation, whereas bacteroid mass per unit nodule mass and bacteroid N concentration did not increase to the level of nonstressed controls until 7 days after alleviation of external P limitation. All of these parameters except bacteroid mass per unit nodule mass decreased to the levels of the P-deficient controls by 11 days after onset of external P limitation. Concentration of ATP in the bacteroid fraction was not significantly affected by alteration in the external P supply. Energy charge in the bacteroid fraction from plants recovering from P deficiency was decreased to a small (10%) but significant extent (P < 0.05) at two sampling dates relative to P-sufficient controls. These ATP concentration and energy charge measurements indicate that P deficiency impaired oxidative phosphorylation in the plant cell fraction of nodules to a much greater extent than in the bacteroids. The concurrence of significant changes in specific nitrogenase activity (2 days) and in the energy charge (2 days) and ATP concentration (4 days) in the plant cell fraction during recovery from external P limitation is consistent with the conclusion that P deficiency decreases the specific nitrogenase activity by inhibiting an energy-dependent reaction(s) in the plant cell fraction of the nodules.
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Claims 16
Claim · model-written summary
Continuous P deficiency decreased whole plant dry mass of soybean relative to P-sufficient controls by 62% at 44 days.
- Taxon
- soybean (Glycine max L. Merr.)
Glycine maxe0 - Treatment
- continuous P deficiency treatment (0.05 millimolar P)e1
- Outcome
- whole plant dry masse1
- Direction
- decreasede1
- Value
- 62e1
- Comparator
- P-sufficient control (1.0 millimolar)e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“energy status of soybean (Glycine max L. Merr.) nodules”
e1“The continuous P deficiency treatment (0.05 millimolar P) significantly decreased the whole plant dry mass, P, and N by 62, 90, and 78%, respectively, relative to the P-sufficient control (1.0 millimolar) at 44 days after transplanting”
Claim · model-written summary
Continuous P deficiency decreased whole plant P of soybean relative to P-sufficient controls by 90%.
- Taxon
- soybean (Glycine max L. Merr.)Glycine maxe0
- Treatment
- continuous P deficiency treatment (0.05 millimolar P)e1
- Outcome
- Pe1
- Direction
- decreasede1
- Value
- 90e1
- Comparator
- P-sufficient control (1.0 millimolar)e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“energy status of soybean (Glycine max L. Merr.) nodules”
e1“The continuous P deficiency treatment (0.05 millimolar P) significantly decreased the whole plant dry mass, P, and N by 62, 90, and 78%, respectively, relative to the P-sufficient control (1.0 millimolar) at 44 days after transplanting”
Claim · model-written summary
Continuous P deficiency decreased whole plant N of soybean relative to P-sufficient controls by 78%.
- Taxon
- soybean (Glycine max L. Merr.)Glycine maxe0
- Treatment
- continuous P deficiency treatment (0.05 millimolar P)e1
- Outcome
- Ne1
- Direction
- decreasede1
- Value
- 78%e1
- Comparator
- P-sufficient control (1.0 millimolar)e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“energy status of soybean (Glycine max L. Merr.) nodules”
e1“The continuous P deficiency treatment (0.05 millimolar P) significantly decreased the whole plant dry mass, P, and N by 62, 90, and 78%, respectively, relative to the P-sufficient control (1.0 millimolar) at 44 days after transplanting”
Claim · model-written summary
P deficiency decreased specific nitrogenase activity in soybean nodules by an average of 28% over 16 days.
- Taxon
- soybean (Glycine max L. Merr.)Glycine maxe0
- Treatment
- P deficiencye2
- Outcome
- Specific nitrogenase activitye2
- Direction
- decreasede2
- Value
- 28%e2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“energy status of soybean (Glycine max L. Merr.) nodules”
e2“Specific nitrogenase activity was decreased an average of 28% over a 16-day experimental period by P deficiency”
Claim · model-written summary
Whole nodules of P-deficient soybean contained 70 to 75% lower ATP concentrations than P-sufficient controls.
- Taxon
- soybean (Glycine max L. Merr.)Glycine maxe0
- Organ / stage
- Whole nodulese3
- Treatment
- P-deficient controlse3
- Outcome
- ATP concentrationse3
- Direction
- lowere3
- Value
- 70 to 75%e3
- Comparator
- P-sufficient controlse3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“energy status of soybean (Glycine max L. Merr.) nodules”
e3“Whole nodules of P-deficient controls contained 70 to 75% lower ATP concentrations than nodules of P-sufficient controls”
Claim · model-written summary
P treatment did not significantly affect energy charge or ATP concentrations in the bacteroid fraction of soybean nodules.
- Taxon
- soybean (Glycine max L. Merr.)Glycine maxe0
- Organ / stage
- bacteroid fraction of nodulese4
- Treatment
- P treatmente4
- Outcome
- Energy charge and ATP concentrationse4
- Direction
- not significantly affectede4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“energy status of soybean (Glycine max L. Merr.) nodules”
e4“Energy charge and ATP concentrations in the bacteroid fraction of nodules were not significantly affected by P treatment”
Claim · model-written summary
P deficiency decreased ATP in the plant cell fraction of soybean nodules by 91%.
- Taxon
- soybean (Glycine max L. Merr.)Glycine maxe0
- Organ / stage
- plant cell fraction of nodulese5
- Treatment
- P deficiency treatmente5
- Outcome
- ATPe5
- Direction
- decreasede5
- Value
- 91e5
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“energy status of soybean (Glycine max L. Merr.) nodules”
e5“ATP and total adenylate concentrations and energy charge in the plant cell fraction of nodules were significantly decreased 91, 62, and 50%, respectively, by the P deficiency treatment”
Claim · model-written summary
P deficiency decreased total adenylate in the plant cell fraction of soybean nodules by 62%.
- Taxon
- soybean (Glycine max L. Merr.)Glycine maxe0
- Organ / stage
- plant cell fraction of nodulese5
- Treatment
- P deficiency treatmente5
- Outcome
- total adenylatee5
- Direction
- decreasede5
- Value
- 62e5
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“energy status of soybean (Glycine max L. Merr.) nodules”
e5“ATP and total adenylate concentrations and energy charge in the plant cell fraction of nodules were significantly decreased 91, 62, and 50%, respectively, by the P deficiency treatment”
Claim · model-written summary
P deficiency decreased energy charge in the plant cell fraction of soybean nodules by 50%.
- Taxon
- soybean (Glycine max L. Merr.)Glycine maxe0
- Organ / stage
- plant cell fraction of nodulese5
- Treatment
- P deficiency treatmente5
- Outcome
- energy chargee5
- Direction
- decreasede5
- Value
- 50%e5
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“energy status of soybean (Glycine max L. Merr.) nodules”
e5“ATP and total adenylate concentrations and energy charge in the plant cell fraction of nodules were significantly decreased 91, 62, and 50%, respectively, by the P deficiency treatment”
Claim · model-written summary
After alleviation of P limitation, nitrogenase activity in the plant cell fraction recovered to nonstressed levels within 2 days.
- Taxon
- soybean (Glycine max L. Merr.)Glycine maxe0
- Organ / stage
- plant cell fractione6
- Treatment
- alleviation of external P limitatione6
- Outcome
- Specific nitrogenase activitye6
- Direction
- increasede6
- Value
- 2e6
- Comparator
- nonstressed controlse6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“energy status of soybean (Glycine max L. Merr.) nodules”
e6“Specific nitrogenase activity, energy charge, and ATP concentration in the plant cell fraction increased to the levels of nonstressed controls within 2, 2, and 4 days, respectively, after alleviation of external P limitation”
Claim · model-written summary
After alleviation of P limitation, energy charge in the plant cell fraction recovered to nonstressed levels within 2 days.
- Taxon
- soybean (Glycine max L. Merr.)Glycine maxe0
- Organ / stage
- plant cell fractione6
- Treatment
- alleviation of external P limitatione6
- Outcome
- energy chargee6
- Direction
- increasede6
- Value
- 2e6
- Comparator
- nonstressed controlse6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“energy status of soybean (Glycine max L. Merr.) nodules”
e6“Specific nitrogenase activity, energy charge, and ATP concentration in the plant cell fraction increased to the levels of nonstressed controls within 2, 2, and 4 days, respectively, after alleviation of external P limitation”
Claim · model-written summary
After alleviation of P limitation, ATP concentration in the plant cell fraction recovered to nonstressed levels within 4 days.
- Taxon
- soybean (Glycine max L. Merr.)Glycine maxe0
- Organ / stage
- plant cell fractione6
- Treatment
- alleviation of external P limitatione6
- Outcome
- ATP concentratione6
- Direction
- increasede6
- Value
- 4e6
- Comparator
- nonstressed controlse6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“energy status of soybean (Glycine max L. Merr.) nodules”
e6“Specific nitrogenase activity, energy charge, and ATP concentration in the plant cell fraction increased to the levels of nonstressed controls within 2, 2, and 4 days, respectively, after alleviation of external P limitation”
Claim · model-written summary
Bacteroid mass per unit nodule mass and bacteroid N concentration did not reach nonstressed levels until 7 days after alleviation of P limitation.
- Taxon
- soybean (Glycine max L. Merr.)Glycine maxe0
- Treatment
- alleviation of external P limitatione7
- Outcome
- bacteroid mass per unit nodule mass and bacteroid N concentratione7
- Direction
- did not increasee7
- Value
- 7e7
- Comparator
- nonstressed controlse7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“energy status of soybean (Glycine max L. Merr.) nodules”
e7“bacteroid mass per unit nodule mass and bacteroid N concentration did not increase to the level of nonstressed controls until 7 days after alleviation of external P limitation”
Claim · model-written summary
Energy charge in the bacteroid fraction of soybean recovering from P deficiency was decreased by 10% relative to P-sufficient controls at two sampling dates.
- Taxon
- soybean (Glycine max L. Merr.)Glycine maxe0
- Organ / stage
- bacteroid fractione1
- Treatment
- plants recovering from P deficiencye1
- Outcome
- Energy chargee1
- Direction
- decreasede1
- Value
- 10%e1
- Qualifier
- at two sampling datese1
- Comparator
- P-sufficient controlse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“energy status of soybean (Glycine max L. Merr.) nodules”
e1“Energy charge in the bacteroid fraction from plants recovering from P deficiency was decreased to a small (10%) but significant extent (P < 0.05) at two sampling dates relative to P-sufficient controls”
Claim · model-written summary
P deficiency is suggested to impair oxidative phosphorylation in the plant cell fraction of soybean nodules more than in the bacteroids.
- Taxon
- soybean (Glycine max L. Merr.)Glycine maxe0
- Organ / stage
- plant cell fraction of nodulese2
- Treatment
- P deficiencye2
- Outcome
- oxidative phosphorylatione2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“energy status of soybean (Glycine max L. Merr.) nodules”
e2“These ATP concentration and energy charge measurements indicate that P deficiency impaired oxidative phosphorylation in the plant cell fraction of nodules to a much greater extent than in the bacteroids”
Claim · model-written summary
P deficiency is concluded to decrease specific nitrogenase activity by inhibiting an energy-dependent reaction in the plant cell fraction of nodules.
- Taxon
- soybean (Glycine max L. Merr.)Glycine maxe0
- Treatment
- P deficiencye3
- Outcome
- specific nitrogenase activitye3
- Qualifier
- inhibiting an energy-dependent reaction(s)e3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“energy status of soybean (Glycine max L. Merr.) nodules”
e3“P deficiency decreases the specific nitrogenase activity by inhibiting an energy-dependent reaction(s) in the plant cell fraction of the nodules”
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