Abstract
Nitrogen is the most important macronutrient in plants and its supply induces responses in gene expression, metabolism and developmental processes. However, the molecular mechanisms underlying the nitrogen responses remain poorly understood. Here we show that the supply of nitrate but not ammonium immediately induces the expression of a transcriptional repressor gene in rice, designated NIGT1 (Nitrate-Inducible, GARP-type Transcriptional Repressor 1). The results of DNA-binding site selection experiments and electrophoretic mobility shift assays indicated that NIGT1 binds to DNA containing either of two consensus sequences, GAATC or GAATATTC. In transient reporter assays, NIGT1 was found to repress transcription from the promoters containing the identified NIGT1-binding sequences in vivo. Furthermore, NIGT1 repressed the activity of its own promoter, suggesting an autorepression mechanism. Consistently, nitrate-induced NIGT1 expression was found to be down-regulated after a transient peak during nitrate treatment, and the nitrate-induced expression of NIGT1 decreased in transgenic rice plants in which this gene was constitutively overexpressed. Furthermore, the chlorophyll content that could be a marker of nitrogen utilization was found to be decreased in NIGT1 overexpressors of rice grown with nitrate medium but not with ammonium medium. Thus, we propose NIGT1 as a nitrate-inducible and autorepressible transcriptional repressor that may play a role in the nitrogen response in rice. Taken together with the fact that the NIGT1-binding sites are conserved in promoter sequences of Arabidopsis NIGT1 homologs, our findings imply the presence of a time-dependent complex system for nitrate-responsive transcriptional regulation that is conserved in both monocots and dicots.
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Claims 8
Claim · model-written summary
Nitrate, but not ammonium, immediately induced NIGT1 expression.
- Taxon
- rice
Oryza sativae0 - Treatment
- nitratee0
- Gene
- NIGT1e0
- Outcome
- expressione0
- Direction
- inducese0
- Comparator
- ammoniume0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the supply of nitrate but not ammonium immediately induces the expression of a transcriptional repressor gene in rice, designated NIGT1”
Claim · model-written summary
NIGT1 bound DNA containing either GAATC or GAATATTC.
- Taxon
- RiceOryza sativat0
- Gene
- NIGT1e0
- Outcome
- binds to DNAe0
- Qualifier
- GAATC or GAATATTCe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“NIGT1 binds to DNA containing either of two consensus sequences, GAATC or GAATATTC.”
t0“Rice”
Claim · model-written summary
NIGT1 repressed transcription from promoters bearing its binding sequences.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“NIGT1 was found to repress transcription from the promoters containing the identified NIGT1-binding sequences in vivo.”
t0“Rice”
Claim · model-written summary
NIGT1 repressed its own promoter activity.
- Taxon
- RiceOryza sativat0
- Gene
- NIGT1e0
- Outcome
- activity of its own promotere0
- Direction
- repressede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“NIGT1 repressed the activity of its own promoter, suggesting an autorepression mechanism.”
t0“Rice”
Claim · model-written summary
Nitrate-induced NIGT1 expression fell after a transient peak.
- Taxon
- RiceOryza sativat0
- Treatment
- nitrate treatmente0
- Gene
- NIGT1e0
- Outcome
- NIGT1 expressione0
- Direction
- down-regulatede0
- Qualifier
- after a transient peake0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“nitrate-induced NIGT1 expression was found to be down-regulated after a transient peak during nitrate treatment”
t0“Rice”
Claim · model-written summary
Nitrate-induced NIGT1 expression decreased in NIGT1-overexpressing rice.
- Taxon
- riceOryza sativae0
- Treatment
- constitutively overexpressede0
- Gene
- NIGT1e0
- Outcome
- nitrate-induced expression of NIGT1e0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the nitrate-induced expression of NIGT1 decreased in transgenic rice plants in which this gene was constitutively overexpressed.”
Claim · model-written summary
NIGT1 overexpressors had decreased chlorophyll with nitrate medium.
- Taxon
- riceOryza sativae0
- Treatment
- NIGT1 overexpressorse0
- Gene
- NIGT1e0
- Outcome
- chlorophyll contente0
- Direction
- decreasede0
- Qualifier
- nitrate mediume0
- Comparator
- ammonium mediume0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the chlorophyll content that could be a marker of nitrogen utilization was found to be decreased in NIGT1 overexpressors of rice grown with nitrate medium but not with ammonium medium.”
Claim · model-written summary
NIGT1-binding sites were conserved in promoters of Arabidopsis homologs.
- Taxon
- Arabidopsis
Arabidopsise0 - Gene
- NIGT1e0
- Outcome
- NIGT1-binding sitese0
- Direction
- conservede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“NIGT1-binding sites are conserved in promoter sequences of Arabidopsis NIGT1 homologs”
The same questions in other papers
nitrogen · molecular: expression · Oryza sativa (rice)Positive and negative results
28 papers in the same direction as this paper · 16 in the opposite direction
- no effect
- negative
- negative
41 papers more in this group
See all 45 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.