Abstract
Nitrite reductase is an enzyme in the nitrate assimilatory pathway whose expression is induced upon the addition of nitrate. Furthermore, it is known to be located in chloroplasts in leaves and plastids in roots. A 3.1 kb 5′ upstream region of the spinach nitrite reductase (NiR) gene promoter was shown previously to confer nitrate inducibility on the β‐glucuronidase (GUS) reporter gene expression in both the leaves and the roots of transgenic tobacco plants. In the present study, this 3.1 kb promoter fragment as well as a series of promoter deletion constructs, fused to a GUS gene, were utilized to delineate the region of NiR promoter involved in nitrate regulation of NiR expression by studying the cellular localization of NiR—GUS expression as well as its regulation by nitrate. In plants carrying the longest promoter fragment (−3100 from the transcription start site) and promoter sequences progressively deleted to −330 bp, the expression of GUS was markedly increased in the presence of nitrate, and this expression was found to occur in mesophyll cells in leaves and in the vascular tissues of stem and roots. When nitrate was added to NiR—GUS plants grown in the absence of nitrate, significant levels of GUS activity could be seen in the roots after 2 h and in the leaves after 6 h. Further 5′ deletion of the promoter to −200 bp abolished the nitrate induction of GUS expression, indicating that the 130 bp region of the nitrite reductase promoter located between −330 and −200 is required for full nitrate‐inducible tissue‐specific expression.
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Claims 6
Claim · model-written summary
Promoter constructs down to −330 bp showed markedly increased GUS expression with nitrate.
- Taxon
- transgenic tobacco
Nicotiana tabacumt0 - Material
- promoter sequences progressively deleted to −330 bpe0
- Treatment
- nitratee0
- Gene
- GUSe0
- Outcome
- expression of GUSe0
- Direction
- markedly increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In plants carrying the longest promoter fragment (−3100 from the transcription start site) and promoter sequences progressively deleted to −330 bp, the expression of GUS was markedly increased in the presence of nitrate”
t0“transgenic tobacco”
Claim · model-written summary
GUS expression occurred in mesophyll cells, and stem and root vascular tissues.
- Taxon
- transgenic tobaccoNicotiana tabacumt0
- Organ / stage
- mesophyll cells in leaves and in the vascular tissues of stem and rootse0
- Outcome
- expressione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“this expression was found to occur in mesophyll cells in leaves and in the vascular tissues of stem and roots”
t0“transgenic tobacco”
Claim · model-written summary
After nitrate addition, GUS activity appeared in roots after 2 h.
- Taxon
- transgenic tobaccoNicotiana tabacumt0
- Organ / stage
- rootse0
- Treatment
- nitratee0
- Gene
- NiR—GUSe0
- Outcome
- GUS activitye0
- Value
- 2 he0
- Comparator
- absence of nitratee0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“When nitrate was added to NiR—GUS plants grown in the absence of nitrate, significant levels of GUS activity could be seen in the roots after 2 h”
t0“transgenic tobacco”
Claim · model-written summary
After nitrate addition, GUS activity appeared in leaves after 6 h.
- Taxon
- transgenic tobaccoNicotiana tabacumt0
- Organ / stage
- leavese0
- Treatment
- nitratee0
- Outcome
- GUS activitye0
- Value
- 6 he0
- Comparator
- absence of nitratee0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“When nitrate was added to NiR—GUS plants grown in the absence of nitrate, significant levels of GUS activity could be seen in the roots after 2 h and in the leaves after 6 h”
t0“transgenic tobacco”
Claim · model-written summary
Deleting the promoter to −200 bp abolished nitrate induction of GUS expression.
- Taxon
- transgenic tobaccoNicotiana tabacumt0
- Treatment
- deletion of the promoter to −200 bpe0
- Gene
- GUSe0
- Outcome
- nitrate induction of GUS expressione0
- Direction
- abolishede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Further 5′ deletion of the promoter to −200 bp abolished the nitrate induction of GUS expression”
t0“transgenic tobacco”
Claim · model-written summary
The promoter region between −330 and −200 is required for full nitrate-inducible tissue-specific expression.
- Taxon
- transgenic tobaccoNicotiana tabacumt0
- Gene
- nitrite reductase promotere0
- Outcome
- full nitrate‐inducible tissue‐specific expressione0
- Value
- 130 bpe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the 130 bp region of the nitrite reductase promoter located between −330 and −200 is required for full nitrate‐inducible tissue‐specific expression”
t0“transgenic tobacco”
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