Abstract
Gibberellin (GA) 20-oxidase catalyses consecutive steps late in GA biosynthesis in plants. In Arabidopsis, the enzyme is encoded by a gene family of at least three members (AtGA20ox1, AtGA20ox2 and AtGA20ox3) with differential patterns of expression. The genes are regulated by feedback from bioactive GAs, suggesting that the enzymes may be involved in regulating GA biosynthesis. To investigate this, we produced transgenic Arabidopsis expressing sense or antisense copies of each of the GA 20-oxidase cDNAs. Over-expression of any of the cDNAs gave rise to seedlings with elongated hypocotyls; the plants flowered earlier than controls in both long and short days and were 25% taller at maturity. GA analysis of the vegetative rosettes showed a two- to threefold increase in the level of GA4, indicating that GA 20-oxidase normally limits bioactive GA levels. Plants expressing antisense copies of AtGA20ox1 had short hypocotyls and reduced rates of stem elongation. This was reflected in reduced levels of GA4 in both rosettes and shoot tips. In short days, flowering was delayed and the reduction in the rate of stem elongation was greater. Antisense expression of AtGA20ox2 had no apparent effects in long days, but stem growth in one transgenic line grown in short days was reduced by 20%. Expression of antisense copies of AtGA20ox3 had no visible effect, except for one transgenic line that had short hypocotyls. These results demonstrate that GA levels and, hence, plant growth and development can be modified by manipulation of GA 20-oxidase expression in transgenic plants.
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Claims 14
Claim · model-written summary
At least three GA 20-oxidase genes have differential expression.
- Taxon
- Arabidopsis
Arabidopsise0 - Gene
- AtGA20ox1, AtGA20ox2 and AtGA20ox3e0
- Outcome
- differential patterns of expressione0
- Value
- at least three memberse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In Arabidopsis, the enzyme is encoded by a gene family of at least three members (AtGA20ox1, AtGA20ox2 and AtGA20ox3) with differential patterns of expression”
Claim · model-written summary
Bioactive GAs feedback regulate the GA 20-oxidase genes.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- genese0
- Compound
- bioactive GAse0
- Outcome
- regulated by feedbacke0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The genes are regulated by feedback from bioactive GAs”
t0“Arabidopsis”
Claim · model-written summary
Overexpressing any GA 20-oxidase cDNA elongated seedling hypocotyls.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- Over-expression of any of the cDNAse0
- Outcome
- elongated hypocotylse0
- Direction
- elongatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Over-expression of any of the cDNAs gave rise to seedlings with elongated hypocotyls”
t0“Arabidopsis”
Claim · model-written summary
Overexpression caused earlier flowering under long and short days.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- Over-expression of any of the cDNAse1
- Outcome
- flowerede0
- Direction
- earliere0
- Qualifier
- both long and short dayse0
- Comparator
- controlse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the plants flowered earlier than controls in both long and short days”
t0“Arabidopsis”
e1“Over-expression of any of the cDNAs gave rise to seedlings with elongated hypocotyls”
Claim · model-written summary
Overexpressing plants were 25% taller at maturity.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- Over-expression of any of the cDNAse1
- Outcome
- tallere0
- Direction
- tallere0
- Value
- 25%e0
- Comparator
- controlse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the plants flowered earlier than controls in both long and short days and were 25% taller at maturity”
t0“Arabidopsis”
e1“Over-expression of any of the cDNAs gave rise to seedlings with elongated hypocotyls”
Claim · model-written summary
Overexpression raised rosette GA4 levels two- to threefold.
- Taxon
- ArabidopsisArabidopsist0
- Organ / stage
- vegetative rosettese0
- Treatment
- Over-expression of any of the cDNAse1
- Outcome
- level of GA4e0
- Direction
- increasee0
- Value
- two- to threefolde0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“GA analysis of the vegetative rosettes showed a two- to threefold increase in the level of GA4”
t0“Arabidopsis”
e1“Over-expression of any of the cDNAs gave rise to seedlings with elongated hypocotyls”
Claim · model-written summary
AtGA20ox1 antisense plants had short hypocotyls and reduced stem elongation.
- Taxon
- PlantsViridiplantaee0
- Treatment
- antisense copies of AtGA20ox1e0
- Gene
- AtGA20ox1e0
- Outcome
- short hypocotyls and reduced rates of stem elongatione0
- Direction
- reducede0
Not reportedComparator
Verbatim
e0“Plants expressing antisense copies of AtGA20ox1 had short hypocotyls and reduced rates of stem elongation”
Claim · model-written summary
AtGA20ox1 antisense reduced GA4 in rosettes and shoot tips.
- Taxon
- ArabidopsisArabidopsist0
- Organ / stage
- rosettes and shoot tipse0
- Treatment
- antisense copies of AtGA20ox1e1
- Outcome
- levels of GA4e0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This was reflected in reduced levels of GA4 in both rosettes and shoot tips”
e1“Plants expressing antisense copies of AtGA20ox1 had short hypocotyls and reduced rates of stem elongation”
t0“Arabidopsis”
Claim · model-written summary
AtGA20ox1 antisense delayed flowering in short days.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- antisense copies of AtGA20ox1e1
- Outcome
- floweringe0
- Direction
- delayede0
- Qualifier
- short dayse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In short days, flowering was delayed and the reduction in the rate of stem elongation was greater”
e1“Plants expressing antisense copies of AtGA20ox1 had short hypocotyls and reduced rates of stem elongation”
t0“Arabidopsis”
Claim · model-written summary
AtGA20ox1 antisense reduced stem elongation more in short days.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- antisense copies of AtGA20ox1e1
- Outcome
- rate of stem elongatione0
- Direction
- reductione0
- Qualifier
- short dayse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In short days, flowering was delayed and the reduction in the rate of stem elongation was greater”
e1“Plants expressing antisense copies of AtGA20ox1 had short hypocotyls and reduced rates of stem elongation”
t0“Arabidopsis”
Claim · model-written summary
AtGA20ox2 antisense had no apparent effects in long days.
- Treatment
- Antisense expression of AtGA20ox2e0
- Outcome
- effectse0
- Direction
- no apparent effectse0
- Qualifier
- long dayse0
Not reportedTaxonComparator
Verbatim
e0“Antisense expression of AtGA20ox2 had no apparent effects in long days”
Claim · model-written summary
One AtGA20ox2 antisense line had 20% less stem growth in short days.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- Antisense expression of AtGA20ox2e1
- Outcome
- stem growthe0
- Direction
- reducede0
- Value
- 20%e0
- Qualifier
- short dayse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“stem growth in one transgenic line grown in short days was reduced by 20%”
e1“Antisense expression of AtGA20ox2 had no apparent effects in long days”
t0“Arabidopsis”
Claim · model-written summary
AtGA20ox3 antisense generally had no visible effect.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- antisense copies of AtGA20ox3e0
- Outcome
- visible effecte0
- Direction
- no visible effecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Expression of antisense copies of AtGA20ox3 had no visible effect, except for one transgenic line that had short hypocotyls”
t0“Arabidopsis”
Claim · model-written summary
One AtGA20ox3 antisense line had short hypocotyls.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- antisense copies of AtGA20ox3e0
- Outcome
- short hypocotylse0
- Direction
- shorte0
- Qualifier
- one transgenic linee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Expression of antisense copies of AtGA20ox3 had no visible effect, except for one transgenic line that had short hypocotyls”
t0“Arabidopsis”
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