Abstract
Common beans (Phaseolus vulgaris L.) were exposed to continuous darkness to induce nodule senescence, and several nodule parameters were investigated to identify factors that may be involved in the initial loss of N2 fixation. After only 1 d of darkness, total root respiration decreased by 76% and in vivo nitrogenase (N2ase) activity decreased by 95%. This decline coincided with the almost complete depletion (97%) of sucrose and fructose in nodules. At this stage, the O2 concentration in the infected zone increased to 1%, which may be sufficient to inactivate N2ase; however, key enzymes of carbon and nitrogen metabolism were still active. After 2 d of dark stress there was a significant decrease in the level of N2ase proteins and in the activities of enzymes involved in carbon and nitrogen assimilation. However, the general collapse of nodule metabolism occurred only after 4 d of stress, with a large decline in leghemoglobin and antioxidants. At this final senescent stage, there was an accumulation of oxidatively modified proteins. This oxidative stress may have originated from the decrease in antioxidant defenses and from the Fe-catalyzed generation of activated oxygen due to the increased availability of catalytic Fe and O2 in the infected region.
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Claims 10
Claim · model-written summary
After 1 day of continuous darkness, total root respiration of common bean decreased by 76%.
- Taxon
- Common Bean
Phaseolus vulgarist0 - Treatment
- darknesse0
- Outcome
- total root respiratione0
- Direction
- decreasede0
- Value
- 76%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“After only 1 d of darkness, total root respiration decreased by 76%”
t0“Common Bean”
Claim · model-written summary
After 1 day of continuous darkness, in vivo nitrogenase activity of common bean decreased by 95%.
- Taxon
- Common BeanPhaseolus vulgarist0
- Treatment
- darknesse0
- Outcome
- in vivo nitrogenase (N2ase) activitye0
- Direction
- decreasede0
- Value
- 95%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“After only 1 d of darkness, total root respiration decreased by 76% and in vivo nitrogenase (N2ase) activity decreased by 95%”
t0“Common Bean”
Claim · model-written summary
The decline in respiration and nitrogenase activity coincided with almost complete (97%) depletion of sucrose and fructose in nodules.
- Taxon
- Common BeanPhaseolus vulgarist0
- Organ / stage
- nodulese0
- Outcome
- sucrose and fructosee0
- Direction
- depletione0
- Value
- 97%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This decline coincided with the almost complete depletion (97%) of sucrose and fructose in nodules”
t0“Common Bean”
Claim · model-written summary
The O2 concentration in the infected zone of nodules increased to 1%.
- Taxon
- Common BeanPhaseolus vulgarist0
- Organ / stage
- infected zonee0
- Outcome
- O2 concentration in the infected zonee0
- Direction
- increasede0
- Value
- 1%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the O2 concentration in the infected zone increased to 1%”
t0“Common Bean”
Claim · model-written summary
At that stage key enzymes of carbon and nitrogen metabolism were still active.
- Taxon
- Common BeanPhaseolus vulgarist0
- Outcome
- key enzymes of carbon and nitrogen metabolism were still activee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“key enzymes of carbon and nitrogen metabolism were still active”
t0“Common Bean”
Claim · model-written summary
After 2 days of dark stress the level of N2ase proteins and the activities of enzymes of carbon and nitrogen assimilation decreased significantly.
- Taxon
- Common BeanPhaseolus vulgarist0
- Treatment
- dark stresse0
- Outcome
- level of N2ase proteins and in the activities of enzymese0
- Direction
- decreasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“After 2 d of dark stress there was a significant decrease in the level of N2ase proteins and in the activities of enzymes involved in carbon and nitrogen assimilation”
t0“Common Bean”
Claim · model-written summary
The general collapse of nodule metabolism occurred only after 4 days of stress.
- Taxon
- Common BeanPhaseolus vulgarist0
- Organ / stage
- nodulee0
- Outcome
- general collapse of nodule metabolisme0
- Qualifier
- only after 4 d of stresse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the general collapse of nodule metabolism occurred only after 4 d of stress, with a large decline in leghemoglobin and antioxidants”
t0“Common Bean”
Claim · model-written summary
After 4 days of stress there was a large decline in leghemoglobin and antioxidants in nodules.
- Taxon
- Common BeanPhaseolus vulgarist0
- Treatment
- stresse0
- Outcome
- leghemoglobin and antioxidantse0
- Direction
- declinee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the general collapse of nodule metabolism occurred only after 4 d of stress, with a large decline in leghemoglobin and antioxidants”
t0“Common Bean”
Claim · model-written summary
At the final senescent stage there was an accumulation of oxidatively modified proteins in nodules.
- Taxon
- Common BeanPhaseolus vulgarist0
- Outcome
- oxidatively modified proteinse0
- Qualifier
- final senescent stagee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At this final senescent stage, there was an accumulation of oxidatively modified proteins”
t0“Common Bean”
Claim · model-written summary
The authors suggest the oxidative stress may have originated from the decrease in antioxidant defenses and from Fe-catalyzed generation of activated oxygen.
- Taxon
- Common BeanPhaseolus vulgarist0
- Compound
- Fee0
- Outcome
- oxidative stresse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This oxidative stress may have originated from the decrease in antioxidant defenses and from the Fe-catalyzed generation of activated oxygen”
t0“Common Bean”
The same questions in other papers
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3 papers more in this group
See all 7 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.