Abstract
RNA polymerase I (pol I) transcribes the repeated genes that encode the precursor of 17-18, 5.8, and 25-28 S ribosomal RNA (rRNA). Pol I transcription is up-regulated in growing cells and down-regulated in quiescent cells, presumably reflecting the demand for ribosomes and protein synthesis. However, the signal transduction pathways responsible for pol I regulation are poorly understood. We tested the effects of exogenously applied plant hormones on promoter-dependent rRNA transcription in Arabidopsis thaliana. Gibberellic acid, abscisic acid, auxin, and ethylene had no detectable effect on rRNA transcription, but kinetin (a cytokinin) stimulated rRNA transcription within 1 h of treatment. Increased steady-state levels of accurately initiated rRNA transcripts, detected by S1 nuclease protection, were paralleled by increased levels of nascent rRNA transcripts in isolated nuclei. Therefore, the primary effect of cytokinin appears to be at the level of transcription initiation rather than rRNA stability. Pol I accounts for approximately 34% of total nuclear transcription in untreated plants and approximately 60% following cytokinin treatment. The specific responsiveness of pol I transcription to kinetin suggests that cytokinins may act as general regulators of protein synthetic capacity and growth status in plant cells.
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Claims 11
Claim · model-written summary
Gibberellic acid had no detectable effect on rRNA transcription in Arabidopsis.
- Taxon
- Arabidopsis thaliana
Arabidopsis thalianae0 - Treatment
- Gibberellic acide1
- Outcome
- rRNA transcriptione1
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“exogenously applied plant hormones on promoter-dependent rRNA transcription in Arabidopsis thaliana”
e1“Gibberellic acid, abscisic acid, auxin, and ethylene had no detectable effect on rRNA transcription”
Claim · model-written summary
Abscisic acid had no detectable effect on rRNA transcription in Arabidopsis.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae0
- Treatment
- abscisic acide1
- Outcome
- rRNA transcriptione1
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“exogenously applied plant hormones on promoter-dependent rRNA transcription in Arabidopsis thaliana”
e1“Gibberellic acid, abscisic acid, auxin, and ethylene had no detectable effect on rRNA transcription”
Claim · model-written summary
Auxin had no detectable effect on rRNA transcription in Arabidopsis.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae0
- Treatment
- auxine1
- Outcome
- rRNA transcriptione1
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“exogenously applied plant hormones on promoter-dependent rRNA transcription in Arabidopsis thaliana”
e1“Gibberellic acid, abscisic acid, auxin, and ethylene had no detectable effect on rRNA transcription”
Claim · model-written summary
Ethylene had no detectable effect on rRNA transcription in Arabidopsis.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae0
- Treatment
- ethylenee1
- Outcome
- rRNA transcriptione1
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“exogenously applied plant hormones on promoter-dependent rRNA transcription in Arabidopsis thaliana”
e1“Gibberellic acid, abscisic acid, auxin, and ethylene had no detectable effect on rRNA transcription”
Claim · model-written summary
Kinetin stimulated rRNA transcription within 1 h of treatment in Arabidopsis.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae0
- Treatment
- kinetine2
- Outcome
- rRNA transcriptione2
- Direction
- stimulatede2
- Qualifier
- within 1 h of treatmente2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“exogenously applied plant hormones on promoter-dependent rRNA transcription in Arabidopsis thaliana”
e2“but kinetin (a cytokinin) stimulated rRNA transcription within 1 h of treatment”
Claim · model-written summary
Kinetin increased steady-state levels of accurately initiated rRNA transcripts in Arabidopsis.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae0
- Treatment
- kinetine2
- Outcome
- steady-state levels of accurately initiated rRNA transcriptse3
- Direction
- Increasede3
- Qualifier
- detected by S1 nuclease protectione3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“exogenously applied plant hormones on promoter-dependent rRNA transcription in Arabidopsis thaliana”
e2“but kinetin (a cytokinin) stimulated rRNA transcription within 1 h of treatment”
e3“Increased steady-state levels of accurately initiated rRNA transcripts, detected by S1 nuclease protection”
Claim · model-written summary
Kinetin increased nascent rRNA transcripts in isolated nuclei of Arabidopsis.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae0
- Treatment
- kinetine2
- Outcome
- nascent rRNA transcriptse4
- Direction
- increasede4
- Qualifier
- in isolated nucleie4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“exogenously applied plant hormones on promoter-dependent rRNA transcription in Arabidopsis thaliana”
e2“but kinetin (a cytokinin) stimulated rRNA transcription within 1 h of treatment”
e4“were paralleled by increased levels of nascent rRNA transcripts in isolated nuclei”
Claim · model-written summary
The primary effect of cytokinin on rRNA transcription appears to be at transcription initiation rather than rRNA stability.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae0
- Compound
- cytokinine5
- Outcome
- transcription initiatione5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“exogenously applied plant hormones on promoter-dependent rRNA transcription in Arabidopsis thaliana”
e5“Therefore, the primary effect of cytokinin appears to be at the level of transcription initiation rather than rRNA stability”
Claim · model-written summary
Pol I accounts for approximately 34% of total nuclear transcription in untreated Arabidopsis plants.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae0
- Outcome
- total nuclear transcriptione6
- Value
- approximately 34%e6
- Qualifier
- in untreated plantse6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“exogenously applied plant hormones on promoter-dependent rRNA transcription in Arabidopsis thaliana”
e6“Pol I accounts for approximately 34% of total nuclear transcription in untreated plants and approximately 60% following cytokinin treatment”
Claim · model-written summary
Pol I accounts for approximately 60% of total nuclear transcription in Arabidopsis following cytokinin treatment.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae0
- Outcome
- total nuclear transcriptione6
- Value
- approximately 60%e6
- Qualifier
- following cytokinin treatmente6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“exogenously applied plant hormones on promoter-dependent rRNA transcription in Arabidopsis thaliana”
e6“Pol I accounts for approximately 34% of total nuclear transcription in untreated plants and approximately 60% following cytokinin treatment”
Claim · model-written summary
Cytokinins may act as general regulators of protein synthetic capacity and growth status (hypothesis).
- Taxon
- Arabidopsis thalianaArabidopsis thalianae0
- Compound
- cytokininse7
- Outcome
- protein synthetic capacity and growth statuse7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“exogenously applied plant hormones on promoter-dependent rRNA transcription in Arabidopsis thaliana”
e7“The specific responsiveness of pol I transcription to kinetin suggests that cytokinins may act as general regulators of protein synthetic capacity and growth status”
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