Abstract
Summary The bacterial UidA gene cloned between the 35S promoter with a double enhancer and the terminator sequences of the pea rbcS 9C gene was introduced into tobacco plants. All 11 transformants carrying the transgene at a single locus showed silencing at each generation, but the timing of silencing occurred at different rates in the different transformants. Two plants showed high levels of UidA mRNA accumulation and GUS activity in young seedlings and a rapid decline of these levels during the first month of growth irrespective of the allelic state of the T‐DNA. The other plants showed high levels of UidA mRNA accumulation and GUS activity in young seedlings and a slow decline of these levels during the first 4 months of growth in homozygous plants, whereas these levels decline only after 1 year of growth in hemizygous plants. Haploids showed the same kinetics of silencing as the homozygous plants from which they derived. Silencing correlated with a strong decrease of the steady‐state level of UidA mRNA, while the transcription of the transgene in the nucleus was not affected. Since haploids and hemizygous plants derived from transformants carrying a single copy of the T‐DNA show silencing, and since all the plants express the transgene at a very high level before the triggering of silencing, the results suggest that post‐transcriptional silencing occurs through a dose effect and not through DNA‐DNA interaction.
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Claims 8
Claim · model-written summary
All 11 single-locus transformants showed silencing in each generation with differing timing.
- Taxon
- tobacco plants
Nicotiana tabacume1 - Gene
- transgenee0
- Outcome
- silencing at each generatione0
- Value
- 11 transformantse0
- Qualifier
- different rates in the different transformantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“All 11 transformants carrying the transgene at a single locus showed silencing at each generation, but the timing of silencing occurred at different rates in the different transformants.”
e1“introduced into tobacco plants.”
Claim · model-written summary
Two plants rapidly lost UidA mRNA and GUS activity in the first month regardless of allelic state.
- Taxon
- tobacco plantsNicotiana tabacume1
- Organ / stage
- young seedlingse0
- Gene
- UidAe0
- Outcome
- UidA mRNA accumulation and GUS activitye0
- Direction
- rapid declinee0
- Value
- Two plantse0
- Qualifier
- during the first month of growth irrespective of the allelic state of the T‐DNAe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Two plants showed high levels of UidA mRNA accumulation and GUS activity in young seedlings and a rapid decline of these levels during the first month of growth irrespective of the allelic state of the T‐DNA.”
e1“introduced into tobacco plants.”
Claim · model-written summary
Other homozygous plants slowly lost UidA mRNA and GUS activity over four months.
- Taxon
- tobacco plantsNicotiana tabacume1
- Material
- homozygous plantse0
- Outcome
- UidA mRNA accumulation and GUS activitye0
- Direction
- slow declinee0
- Qualifier
- during the first 4 months of growthe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The other plants showed high levels of UidA mRNA accumulation and GUS activity in young seedlings and a slow decline of these levels during the first 4 months of growth in homozygous plants, whereas these levels decline only after 1 year of growth in hemizygous plants.”
e1“introduced into tobacco plants.”
Claim · model-written summary
Hemizygous plants showed decline only after one year.
- Taxon
- tobacco plantsNicotiana tabacume1
- Material
- hemizygous plantse0
- Outcome
- UidA mRNA accumulation and GUS activitye0
- Direction
- declinee0
- Qualifier
- only after 1 year of growthe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The other plants showed high levels of UidA mRNA accumulation and GUS activity in young seedlings and a slow decline of these levels during the first 4 months of growth in homozygous plants, whereas these levels decline only after 1 year of growth in hemizygous plants.”
e1“introduced into tobacco plants.”
Claim · model-written summary
Haploids had the same silencing kinetics as their homozygous parents.
- Taxon
- tobacco plantsNicotiana tabacume1
- Material
- Haploidse0
- Outcome
- same kinetics of silencinge0
- Comparator
- homozygous plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Haploids showed the same kinetics of silencing as the homozygous plants from which they derived.”
e1“introduced into tobacco plants.”
Claim · model-written summary
Silencing correlated with a strong decrease in steady-state UidA mRNA.
- Taxon
- tobacco plantsNicotiana tabacume1
- Gene
- UidAe0
- Outcome
- steady‐state level of UidA mRNAe0
- Direction
- strong decreasee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Silencing correlated with a strong decrease of the steady‐state level of UidA mRNA, while the transcription of the transgene in the nucleus was not affected.”
e1“introduced into tobacco plants.”
Claim · model-written summary
Nuclear transgene transcription was unaffected during silencing.
- Taxon
- tobacco plantsNicotiana tabacume1
- Gene
- transgenee0
- Outcome
- transcription of the transgene in the nucleuse0
- Direction
- not affectede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Silencing correlated with a strong decrease of the steady‐state level of UidA mRNA, while the transcription of the transgene in the nucleus was not affected.”
e1“introduced into tobacco plants.”
Claim · model-written summary
The authors infer post-transcriptional silencing arises through a dose effect.
- Taxon
- tobacco plantsNicotiana tabacume1
- Outcome
- post‐transcriptional silencinge0
- Qualifier
- dose effect and not through DNA‐DNA interactione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the results suggest that post‐transcriptional silencing occurs through a dose effect and not through DNA‐DNA interaction.”
e1“introduced into tobacco plants.”