Abstract
Using a novel system for expressing ipt gene in tobacco, we were able to increase cytokinins in plant tissue. This enabled us to study new regulatory aspects of nitrate (NO3-) reduction. We have grown plants with elevated cytokinins on MS with variable NO3- and benzyladenine (BA). We determined nitrate reductase activity (NRA) in this plant material. Initially, we found that ipt-expressing plants always display lower NRA than wild-type SR1 plants. We also found that long-term exposure of tobacco to cytokinins caused up to 60% decrease in NRA. However, addition of BA to N-starved plants caused induction of NRA to levels up to 100% higher than those before induction. In ipt-expressing plants this effect was only present if BA was administered together with NO3-. Exposure to 40mM NO3- caused up to 550% induction of NRA. This effect was always more pronounced in wild-type plants. We propose that regulation of NR by NO3- and cytokinins is a result of overlaying regulatory processes, with short-term ones having positive effect on NRA and those acting over extended periods having inhibitory effects on NRA.
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Claims 8
Claim · model-written summary
The ipt expression system increased cytokinin levels in tobacco tissue.
- Taxon
- tobacco
Nicotiana tabacume0 - Treatment
- expressing ipt genee0
- Gene
- ipt genee0
- Outcome
- cytokinins in plant tissuee0
- Direction
- increasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Using a novel system for expressing ipt gene in tobacco, we were able to increase cytokinins in plant tissue”
Claim · model-written summary
ipt-expressing tobacco plants consistently showed lower NRA than wild-type SR1.
- Taxon
- tobaccoNicotiana tabacume1
- Material
- ipt-expressing plantse0
- Outcome
- NRAe0
- Direction
- lowere0
- Comparator
- wild-type SR1 plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“ipt-expressing plants always display lower NRA than wild-type SR1 plants”
e1“ipt gene in tobacco”
Claim · model-written summary
Long-term cytokinin exposure decreased tobacco NRA by up to 60%.
- Taxon
- tobaccoNicotiana tabacume0
- Treatment
- long-term exposure of tobacco to cytokininse0
- Outcome
- NRAe0
- Direction
- decreasee0
- Value
- 60%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“long-term exposure of tobacco to cytokinins caused up to 60% decrease in NRA”
Claim · model-written summary
BA addition induced NRA in nitrogen-starved tobacco by up to 100% above pre-induction levels.
- Taxon
- tobaccoNicotiana tabacume1
- Treatment
- addition of BA to N-starved plantse0
- Outcome
- NRAe0
- Direction
- highere0
- Value
- 100%e0
- Comparator
- those before inductione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“addition of BA to N-starved plants caused induction of NRA to levels up to 100% higher than those before induction”
e1“tobacco to cytokinins”
Claim · model-written summary
BA induced NRA in ipt-expressing tobacco only when supplied with nitrate.
- Taxon
- tobaccoNicotiana tabacume1
- Material
- ipt-expressing plantse0
- Treatment
- BA was administered together with NO3-e0
- Outcome
- this effect was only presente0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In ipt-expressing plants this effect was only present if BA was administered together with NO3-”
e1“ipt gene in tobacco”
Claim · model-written summary
Exposure to 40mM nitrate induced tobacco NRA by up to 550%.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Exposure to 40mM NO3- caused up to 550% induction of NRA”
e1“ipt gene in tobacco”
Claim · model-written summary
Nitrate induction of NRA was stronger in wild-type tobacco than ipt-expressing plants.
- Taxon
- tobaccoNicotiana tabacume2
- Material
- wild-type plantse0
- Outcome
- induction of NRAe1
- Direction
- more pronouncede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This effect was always more pronounced in wild-type plants”
e1“Exposure to 40mM NO3- caused up to 550% induction of NRA”
e2“ipt gene in tobacco”
Claim · model-written summary
The authors propose that short-term nitrate and cytokinin regulation positively affects NRA while prolonged processes inhibit it.
- Taxon
- tobaccoNicotiana tabacume1
- Outcome
- NRAe0
- Qualifier
- overlaying regulatory processese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“regulation of NR by NO3- and cytokinins is a result of overlaying regulatory processes, with short-term ones having positive effect on NRA and those acting over extended periods having inhibitory effects on NRA”
e1“ipt gene in tobacco”
The same questions in other papers
N-benzyladenine · physiology: enzyme activity · Nicotiana tabacum (tobacco)Positive and negative results
1 in the opposite direction
- negative
class · physiology: enzyme activity · Nicotiana tabacum (tobacco)Positive and negative results
1 paper in the same direction as this paper · 2 in the opposite direction
- positive
- positive
- no effect
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.