Abstract
Desiccation of 8- to 13-day-old seedlings, achieved by withholding nutrient solution from the vermiculite root medium, caused a reduction in nitrate reductase activity of the leaf tissue. Activity declined when leaf water potentials decreased below -2 bars and was 25% of the control at a leaf water potential of -13 bars. Experiments were conducted to determine whether the decrease in nitrate reductase activity was due to reduced levels of nitrate in the tissue, direct inactivation of the enzyme by low leaf water potentials, or to changes in rates of synthesis or decay of the enzyme.Although tissue nitrate content decreased with the onset of desiccation, it did not continue to decline with tissue desiccation and loss of enzyme activity. Nitrate reductase activity recovered when the plants were rewatered with nitrate-free medium, suggesting that the nitrate in the plant was adequate for high nitrate reductase activity. The rate of decay of nitrate reductase activity from desiccated tissue was essentially identical to that of the control, in vivo or in vitro, regardless of the rapidity of desiccation of the tissue. Direct inactivation of the enzyme by the low water potentials was not detected. Polyribosomal content of the tissue declined with the decrease in water potential, prior to the decline in nitrate reductase activity. Changes in ribosomal profiles occurred during desiccation, regardless of whether the tissue had been excised or not and whether desiccation was rapid or slow. Reduction in polyribosomal content did not appear to be associated with changes in ribonuclease activity. Nitrate reductase activity and the polyribosomal content of the tissue recovered upon rewatering, following the recovery in water potential. The increase in polyribosomal content preceded the increase in nitrate reductase activity. Recovery of enzyme activity was prevented by cycloheximide.Based on these results, it appears that nitrate reductase activity was affected primarily by a decrease in the rate of enzyme synthesis at low leaf water potentials.
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Claims 14
Claim · model-written summary
Desiccation reduced leaf nitrate reductase activity.
- Taxon
- Corn
Zea mays subsp. mayst0 - Organ / stage
- leaf tissuee0
- Treatment
- withholding nutrient solutione0
- Outcome
- nitrate reductase activitye0
- Direction
- reductione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Desiccation of 8- to 13-day-old seedlings, achieved by withholding nutrient solution from the vermiculite root medium, caused a reduction in nitrate reductase activity of the leaf tissue.”
t0“Corn (Zea mays L.)”
Claim · model-written summary
Activity declined below -2 bars and reached 25% of control at -13 bars.
- Taxon
- CornZea mays subsp. mayst0
- Outcome
- Activitye0
- Direction
- declinede0
- Value
- 25%e0
- Qualifier
- leaf water potential of -13 barse0
- Comparator
- controle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Activity declined when leaf water potentials decreased below -2 bars and was 25% of the control at a leaf water potential of -13 bars.”
t0“Corn (Zea mays L.)”
Claim · model-written summary
Tissue nitrate content decreased at the onset of desiccation.
- Taxon
- CornZea mays subsp. mayst0
- Outcome
- tissue nitrate contente0
- Direction
- decreasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Although tissue nitrate content decreased with the onset of desiccation”
t0“Corn (Zea mays L.)”
Claim · model-written summary
Tissue nitrate content did not continue declining with further desiccation.
- Taxon
- CornZea mays subsp. mayst0
- Outcome
- enzyme activitye0
- Direction
- did not continue to declinee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“it did not continue to decline with tissue desiccation and loss of enzyme activity”
t0“Corn (Zea mays L.)”
Claim · model-written summary
Nitrate reductase activity recovered after rewatering with nitrate-free medium.
- Taxon
- CornZea mays subsp. mayst0
- Treatment
- rewatered with nitrate-free mediume0
- Outcome
- Nitrate reductase activitye0
- Direction
- recoverede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nitrate reductase activity recovered when the plants were rewatered with nitrate-free medium”
t0“Corn (Zea mays L.)”
Claim · model-written summary
Nitrate reductase activity decayed at essentially the same rate in desiccated and control tissue.
- Taxon
- CornZea mays subsp. mayst0
- Outcome
- rate of decay of nitrate reductase activitye0
- Direction
- essentially identicale0
- Comparator
- controle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The rate of decay of nitrate reductase activity from desiccated tissue was essentially identical to that of the control, in vivo or in vitro, regardless of the rapidity of desiccation of the tissue.”
t0“Corn (Zea mays L.)”
Claim · model-written summary
Direct enzyme inactivation at low water potential was not detected.
- Taxon
- CornZea mays subsp. mayst0
- Outcome
- Direct inactivation of the enzymee0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Direct inactivation of the enzyme by the low water potentials was not detected.”
t0“Corn (Zea mays L.)”
Claim · model-written summary
Polyribosomal content fell as water potential declined, before nitrate reductase activity fell.
- Taxon
- CornZea mays subsp. mayst0
- Outcome
- Polyribosomal contente0
- Direction
- declinede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Polyribosomal content of the tissue declined with the decrease in water potential, prior to the decline in nitrate reductase activity.”
t0“Corn (Zea mays L.)”
Claim · model-written summary
Ribosomal profiles changed during both rapid and slow desiccation in excised and intact tissue.
- Taxon
- CornZea mays subsp. mayst0
- Outcome
- Changes in ribosomal profilese0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Changes in ribosomal profiles occurred during desiccation, regardless of whether the tissue had been excised or not and whether desiccation was rapid or slow.”
t0“Corn (Zea mays L.)”
Claim · model-written summary
Reduced polyribosomal content did not appear associated with ribonuclease activity changes.
- Taxon
- CornZea mays subsp. mayst0
- Gene
- ribonucleasee0
- Outcome
- polyribosomal contente0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Reduction in polyribosomal content did not appear to be associated with changes in ribonuclease activity.”
t0“Corn (Zea mays L.)”
Claim · model-written summary
Rewatering restored nitrate reductase activity and polyribosomal content after water potential recovered.
- Taxon
- CornZea mays subsp. mayst0
- Treatment
- rewateringe0
- Outcome
- Nitrate reductase activity and the polyribosomal contente0
- Direction
- recoverede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nitrate reductase activity and the polyribosomal content of the tissue recovered upon rewatering, following the recovery in water potential.”
t0“Corn (Zea mays L.)”
Claim · model-written summary
Polyribosomal content rose before nitrate reductase activity.
- Taxon
- CornZea mays subsp. mayst0
- Outcome
- polyribosomal contente0
- Direction
- increasee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The increase in polyribosomal content preceded the increase in nitrate reductase activity.”
t0“Corn (Zea mays L.)”
Claim · model-written summary
Cycloheximide prevented recovery of enzyme activity.
- Taxon
- CornZea mays subsp. mayst0
- Treatment
- cycloheximidee0
- Outcome
- Recovery of enzyme activitye0
- Direction
- preventede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Recovery of enzyme activity was prevented by cycloheximide.”
t0“Corn (Zea mays L.)”
Claim · model-written summary
The authors infer that low water potential reduced enzyme synthesis, primarily affecting nitrate reductase activity.
- Taxon
- CornZea mays subsp. mayst0
- Outcome
- nitrate reductase activitye0
- Qualifier
- decrease in the rate of enzyme synthesise0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“it appears that nitrate reductase activity was affected primarily by a decrease in the rate of enzyme synthesis at low leaf water potentials.”
t0“Corn (Zea mays L.)”
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See all 36 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.