Abstract
Transformed (cauliflower mosaic virus 35S promoter [35S]) tobacco (Nicotiana plumbaginifolia L.) plants constitutively expressing nitrate reductase (NR) and untransformed controls were subjected to drought for 5 d. Drought-induced changes in biomass accumulation and photosynthesis were comparable in both lines of plants. After 4 d of water deprivation, a large increase in the ratio of shoot dry weight to fresh weight was observed, together with a decrease in the rate of photosynthetic CO2 assimilation. Foliar sucrose increased in both lines during water stress, but hexoses increased only in leaves from untransformed controls. Foliar NO3- decreased rapidly in both lines and was halved within 2 d of the onset of water deprivation. Total foliar amino acids decreased in leaves of both lines following water deprivation. After 4 d of water deprivation no NR activity could be detected in leaves of untransformed plants, whereas about 50% of the original activity remained in the leaves of the 35S-NR transformants. NR mRNA was much more stable than NR activity. NR mRNA abundance increased in the leaves of the 35S-NR plants and remained constant in controls for the first 3 d of drought. On the 4th d, however, NR mRNA suddenly decreased in both lines. Rehydration at d 3 caused rapid recovery (within 24 h) of 35S-NR transcripts, but no recovery was observed in the controls. The phosphorylation state of the protein was unchanged by long-term drought. There was a strong correlation between maximal extractable NR activity and ambient photosynthesis in both lines. We conclude that drought first causes increased NR protein turnover and then accelerates NR mRNA turnover. Constitutive NR expression temporarily delayed drought-induced losses in NR activity. 35S-NR expression may therefore allow more rapid recovery of N assimilation following short-term water deficit.
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Claims 20
Claim · model-written summary
Drought changed biomass accumulation comparably in transformed and control plants.
- Taxon
- Tobacco
Nicotiana tabacumt0 - Treatment
- Drought-inducede0
- Outcome
- biomass accumulatione0
- Direction
- comparablee0
- Comparator
- both lines of plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Tobacco”
e0“Drought-induced changes in biomass accumulation and photosynthesis were comparable in both lines of plants.”
Claim · model-written summary
Drought changed photosynthesis comparably in transformed and control plants.
- Taxon
- TobaccoNicotiana tabacumt0
- Treatment
- Drought-inducede0
- Outcome
- photosynthesise0
- Direction
- comparablee0
- Comparator
- both lines of plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Tobacco”
e0“Drought-induced changes in biomass accumulation and photosynthesis were comparable in both lines of plants.”
Claim · model-written summary
Four days of water deprivation increased the shoot dry to fresh weight ratio.
- Taxon
- TobaccoNicotiana tabacumt0
- Treatment
- water deprivatione0
- Outcome
- ratio of shoot dry weight to fresh weighte0
- Direction
- increasee0
- Qualifier
- After 4 de0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Tobacco”
e0“After 4 d of water deprivation, a large increase in the ratio of shoot dry weight to fresh weight was observed”
Claim · model-written summary
Four days of water deprivation decreased photosynthetic CO2 assimilation.
- Taxon
- TobaccoNicotiana tabacumt0
- Treatment
- water deprivatione0
- Outcome
- rate of photosynthetic CO2 assimilatione0
- Direction
- decreasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Tobacco”
e0“After 4 d of water deprivation, a large increase in the ratio of shoot dry weight to fresh weight was observed, together with a decrease in the rate of photosynthetic CO2 assimilation.”
Claim · model-written summary
Foliar sucrose rose in both lines during water stress.
- Taxon
- TobaccoNicotiana tabacumt0
- Treatment
- water stresse0
- Outcome
- Foliar sucrosee0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Tobacco”
e0“Foliar sucrose increased in both lines during water stress”
Claim · model-written summary
Hexoses rose only in untransformed control leaves during water stress.
- Taxon
- TobaccoNicotiana tabacumt0
- Treatment
- water stresse1
- Outcome
- hexosese0
- Direction
- increasede0
- Comparator
- untransformed controlse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Tobacco”
e0“hexoses increased only in leaves from untransformed controls”
e1“Foliar sucrose increased in both lines during water stress”
Claim · model-written summary
Foliar nitrate fell by half within two days of water deprivation in both lines.
- Taxon
- TobaccoNicotiana tabacumt0
- Treatment
- water deprivatione0
- Outcome
- Foliar NO3-e0
- Direction
- decreasede0
- Value
- halved within 2 de0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Tobacco”
e0“Foliar NO3- decreased rapidly in both lines and was halved within 2 d of the onset of water deprivation.”
Claim · model-written summary
Water deprivation reduced total foliar amino acids in both lines.
- Taxon
- TobaccoNicotiana tabacumt0
- Treatment
- water deprivatione0
- Outcome
- Total foliar amino acidse0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Tobacco”
e0“Total foliar amino acids decreased in leaves of both lines following water deprivation.”
Claim · model-written summary
After four days without water, nitrate reductase activity was undetectable in untransformed leaves.
- Taxon
- TobaccoNicotiana tabacumt0
- Treatment
- water deprivatione0
- Outcome
- NR activitye0
- Direction
- no NR activity could be detectede0
- Qualifier
- After 4 de0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Tobacco”
e0“After 4 d of water deprivation no NR activity could be detected in leaves of untransformed plants”
Claim · model-written summary
After four days without water, transformed leaves retained about 50% of original nitrate reductase activity.
- Taxon
- TobaccoNicotiana tabacumt0
- Treatment
- 35S-NR transformantse0
- Outcome
- activitye0
- Direction
- remainede0
- Value
- about 50%e0
- Comparator
- original activitye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Tobacco”
e0“about 50% of the original activity remained in the leaves of the 35S-NR transformants”
Claim · model-written summary
During early drought, nitrate reductase mRNA abundance rose in 35S-NR leaves but stayed constant in controls.
- Taxon
- TobaccoNicotiana tabacumt0
- Material
- 35S-NR plantse0
- Gene
- NR mRNAe0
- Outcome
- NR mRNA abundancee0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Tobacco”
e0“NR mRNA abundance increased in the leaves of the 35S-NR plants and remained constant in controls for the first 3 d of drought.”
Claim · model-written summary
During early drought, nitrate reductase mRNA abundance stayed constant in controls.
- Taxon
- TobaccoNicotiana tabacumt0
- Gene
- NR mRNAe0
- Outcome
- NR mRNA abundancee0
- Direction
- remained constante0
- Comparator
- controlse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Tobacco”
e0“NR mRNA abundance increased in the leaves of the 35S-NR plants and remained constant in controls for the first 3 d of drought.”
Claim · model-written summary
On drought day four, nitrate reductase mRNA fell in both lines.
- Taxon
- TobaccoNicotiana tabacumt0
- Treatment
- 4th de0
- Outcome
- NR mRNAe0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Tobacco”
e0“On the 4th d, however, NR mRNA suddenly decreased in both lines.”
Claim · model-written summary
Rehydration on day three rapidly restored 35S-NR transcripts within 24 hours.
- Taxon
- TobaccoNicotiana tabacumt0
- Treatment
- Rehydration at d 3e0
- Outcome
- 35S-NR transcriptse0
- Direction
- recoverye0
- Value
- within 24 he0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Tobacco”
e0“Rehydration at d 3 caused rapid recovery (within 24 h) of 35S-NR transcripts”
Claim · model-written summary
Rehydration produced no transcript recovery in controls.
- Taxon
- TobaccoNicotiana tabacumt0
- Outcome
- recoverye0
- Direction
- no recoverye0
- Comparator
- controlse0
Not reportedTreatment
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Tobacco”
e0“but no recovery was observed in the controls.”
Claim · model-written summary
Long-term drought left nitrate reductase phosphorylation state unchanged.
- Taxon
- TobaccoNicotiana tabacumt0
- Treatment
- long-term droughte0
- Outcome
- phosphorylation state of the proteine0
- Direction
- unchangede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Tobacco”
e0“The phosphorylation state of the protein was unchanged by long-term drought.”
Claim · model-written summary
Maximal extractable nitrate reductase activity strongly correlated with ambient photosynthesis in both lines.
- Taxon
- TobaccoNicotiana tabacumt0
- Gene
- NRe0
- Outcome
- ambient photosynthesise0
- Qualifier
- strong correlatione0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Tobacco”
e0“There was a strong correlation between maximal extractable NR activity and ambient photosynthesis in both lines.”
Claim · model-written summary
Authors infer that drought first accelerates nitrate reductase protein turnover then mRNA turnover.
- Taxon
- TobaccoNicotiana tabacumt0
- Treatment
- droughte0
- Gene
- NRe0
- Outcome
- NR protein turnover and then accelerates NR mRNA turnovere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Tobacco”
e0“drought first causes increased NR protein turnover and then accelerates NR mRNA turnover”
Claim · model-written summary
Constitutive nitrate reductase expression temporarily delayed drought-related loss of enzyme activity.
- Taxon
- TobaccoNicotiana tabacumt0
- Treatment
- Constitutive NR expressione0
- Outcome
- NR activitye0
- Direction
- delayede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Tobacco”
e0“Constitutive NR expression temporarily delayed drought-induced losses in NR activity.”
Claim · model-written summary
Authors suggest 35S-NR expression may hasten nitrogen assimilation recovery after short water deficit.
- Taxon
- TobaccoNicotiana tabacumt0
- Gene
- 35S-NRe0
- Outcome
- recovery of N assimilatione0
- Qualifier
- following short-term water deficite0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Tobacco”
e0“35S-NR expression may therefore allow more rapid recovery of N assimilation following short-term water deficit.”
The same questions in other papers
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See all 8 papers →drought · molecular: expression · Nicotiana tabacum (tobacco)Positive and negative results
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See all 16 papers →rewatering · molecular: expression · Nicotiana tabacum (tobacco)Results agree
1 paper in the same direction as this paper
- positive
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.