Abstract
How growth regulators provoke context-specific signals is a fundamental question in developmental biology. In plants, both auxin and brassinosteroids (BRs) promote cell expansion, and it was thought that they activated this process through independent mechanisms. In this work, we describe a shared auxin:BR pathway required for seedling growth. Genetic, physiological, and genomic analyses demonstrate that response from one pathway requires the function of the other, and that this interdependence does not act at the level of hormone biosynthetic control. Increased auxin levels saturate the BR-stimulated growth response and greatly reduce BR effects on gene expression. Integration of these two pathways is downstream from BES1 and Aux/IAA proteins, the last known regulatory factors acting downstream of each hormone, and is likely to occur directly on the promoters of auxin:BR target genes. We have developed a new approach to identify potential regulatory elements acting in each hormone pathway, as well as in the shared auxin:BR pathway. We show that one element highly overrepresented in the promoters of auxin- and BR-induced genes is responsive to both hormones and requires BR biosynthesis for normal expression. This work fundamentally alters our view of BR and auxin signaling and describes a powerful new approach to identify regulatory elements required for response to specific stimuli.
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Claims 8
Claim · model-written summary
Auxin and brassinosteroid signaling depend on each other for seedling growth.
- Taxon
- Arabidopsis
Arabidopsist0 - Outcome
- response from one pathwaye0
- Qualifier
- requires the function of the othere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“response from one pathway requires the function of the other”
t0“Arabidopsis”
Claim · model-written summary
This pathway interdependence does not occur through hormone biosynthesis.
- Taxon
- ArabidopsisArabidopsist0
- Outcome
- hormone biosynthetic controle0
- Qualifier
- does not acte0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“this interdependence does not act at the level of hormone biosynthetic control”
t0“Arabidopsis”
Claim · model-written summary
Increased auxin saturates the brassinosteroid-stimulated growth response.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- Increased auxin levelse0
- Outcome
- BR-stimulated growth responsee0
- Direction
- saturatee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Increased auxin levels saturate the BR-stimulated growth response”
t0“Arabidopsis”
Claim · model-written summary
Increased auxin greatly reduces brassinosteroid effects on gene expression.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- Increased auxin levelse0
- Outcome
- BR effects on gene expressione0
- Direction
- reducee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Increased auxin levels saturate the BR-stimulated growth response and greatly reduce BR effects on gene expression”
t0“Arabidopsis”
Claim · model-written summary
The two pathways integrate downstream of BES1 and Aux/IAA proteins, likely at target-gene promoters.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- BES1 and Aux/IAA proteinse0
- Outcome
- Integration of these two pathwayse0
- Qualifier
- is likely to occur directly on the promoters of auxin:BR target genese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Integration of these two pathways is downstream from BES1 and Aux/IAA proteins, the last known regulatory factors acting downstream of each hormone, and is likely to occur directly on the promoters of auxin:BR target genes”
t0“Arabidopsis”
Claim · model-written summary
A regulatory element overrepresented in auxin and brassinosteroid induced gene promoters responds to both hormones.
- Taxon
- ArabidopsisArabidopsist0
- Outcome
- one elemente0
- Qualifier
- responsive to both hormonese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“one element highly overrepresented in the promoters of auxin- and BR-induced genes is responsive to both hormones”
t0“Arabidopsis”
Claim · model-written summary
Normal expression of that regulatory element requires brassinosteroid biosynthesis.
- Taxon
- ArabidopsisArabidopsist0
- Outcome
- normal expressione0
- Qualifier
- requires BR biosynthesise0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“one element highly overrepresented in the promoters of auxin- and BR-induced genes is responsive to both hormones and requires BR biosynthesis for normal expression”
t0“Arabidopsis”
Claim · model-written summary
The authors developed an approach to identify regulatory elements in individual and shared hormone pathways.
- Taxon
- ArabidopsisArabidopsist0
- Outcome
- potential regulatory elementse0
Not reportedComparatorValue
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“We have developed a new approach to identify potential regulatory elements acting in each hormone pathway, as well as in the shared auxin:BR pathway”
t0“Arabidopsis”
The same questions in other papers
class · molecular: expression · ArabidopsisPositive and negative results
28 papers in the same direction as this paper · 46 in the opposite direction
- positive
- positive
- no effect
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