Abstract
Brassinosteroids (BRs) are hormones that control many aspects of plant growth and development, acting at the cell level to promote division and expansion. BR regulation of plant and plant cell function occurs through altered expression of many genes. Transcriptional reprogramming downstream from cell perception of this hormone is currently known to be mediated by a phosphorylation/dephosphorylation ("phosphorelay") cascade that alters the stability of two master transcription regulators. Here, we provide evidence that BR perception by their receptor also causes an elevation in cytosolic Ca(2+), initiating a Ca(2+) signaling cascade in Arabidopsis (Arabidopsis thaliana) cell cytosol. BR-dependent increases in the expression of some genes (INDOLE-3-ACETIC ACID-INDUCIBLE1 and PHYTOCHROME B ACTIVATION-TAGGED SUPPRESSOR1) were impaired in wild-type plants by a Ca(2+) channel blocker and also in the defense-no-death (dnd1) mutant, which lacks a functional cyclic GMP-activated cell membrane Ca(2+)-conducting channel. Alternatively, mutations that impair the BR phosphorelay cascade did not much affect the BR-dependent expression of these genes. Similar effects of the Ca(2+) channel blocker and dnd1 mutation were observed on a BR plant growth phenotype, deetiolation of the seedling hypocotyl. Further evidence presented in this report suggests that a BR-dependent elevation in cyclic GMP may be involved in the Ca(2+) signaling cascade initiated by this hormone. The work presented here leads to a new model of the molecular steps that mediate some of the cell responses to this plant hormone.
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Claims 7
Claim · model-written summary
Brassinosteroid perception elevated cytosolic calcium in Arabidopsis cells.
- Taxon
- Arabidopsis
Arabidopsise0 - Organ / stage
- cell cytosole0
- Treatment
- BR perceptione0
- Outcome
- cytosolic Ca(2+)e0
- Direction
- elevatione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“BR perception by their receptor also causes an elevation in cytosolic Ca(2+), initiating a Ca(2+) signaling cascade in Arabidopsis (Arabidopsis thaliana) cell cytosol”
Claim · model-written summary
A calcium channel blocker impaired BR-dependent expression of two named genes in wild-type plants.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- Ca(2+) channel blockere0
- Gene
- INDOLE-3-ACETIC ACID-INDUCIBLE1 and PHYTOCHROME B ACTIVATION-TAGGED SUPPRESSOR1e0
- Outcome
- BR-dependent increases in the expression of some genese0
- Direction
- impairede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“BR-dependent increases in the expression of some genes (INDOLE-3-ACETIC ACID-INDUCIBLE1 and PHYTOCHROME B ACTIVATION-TAGGED SUPPRESSOR1) were impaired in wild-type plants by a Ca(2+) channel blocker”
t0“in Arabidopsis (Arabidopsis thaliana) cell cytosol”
Claim · model-written summary
The dnd1 mutation impaired BR-dependent expression of the named genes.
- Taxon
- ArabidopsisArabidopsist0
- Material
- defense-no-death (dnd1) mutante0
- Outcome
- BR-dependent increases in the expression of some genese1
- Direction
- impairede1
Not reportedTreatmentComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“and also in the defense-no-death (dnd1) mutant, which lacks a functional cyclic GMP-activated cell membrane Ca(2+)-conducting channel”
t0“in Arabidopsis (Arabidopsis thaliana) cell cytosol”
e1“BR-dependent increases in the expression of some genes (INDOLE-3-ACETIC ACID-INDUCIBLE1 and PHYTOCHROME B ACTIVATION-TAGGED SUPPRESSOR1) were impaired”
Claim · model-written summary
Mutations affecting the BR phosphorelay had little effect on BR-dependent expression of these genes.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- mutations that impair the BR phosphorelay cascadee0
- Outcome
- BR-dependent expression of these genese0
- Direction
- did not much affecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“mutations that impair the BR phosphorelay cascade did not much affect the BR-dependent expression of these genes”
t0“in Arabidopsis (Arabidopsis thaliana) cell cytosol”
Claim · model-written summary
A calcium channel blocker affected BR-dependent seedling hypocotyl deetiolation.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- Ca(2+) channel blockere0
- Outcome
- deetiolation of the seedling hypocotyle0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Similar effects of the Ca(2+) channel blocker and dnd1 mutation were observed on a BR plant growth phenotype, deetiolation of the seedling hypocotyl”
t0“in Arabidopsis (Arabidopsis thaliana) cell cytosol”
Claim · model-written summary
The dnd1 mutation affected BR-dependent seedling hypocotyl deetiolation.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- dnd1 mutatione0
- Outcome
- deetiolation of the seedling hypocotyle0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Similar effects of the Ca(2+) channel blocker and dnd1 mutation were observed on a BR plant growth phenotype, deetiolation of the seedling hypocotyl”
t0“in Arabidopsis (Arabidopsis thaliana) cell cytosol”
Claim · model-written summary
The authors suggest that BR-dependent cyclic GMP elevation participates in calcium signaling.
- Taxon
- ArabidopsisArabidopsist0
- Compound
- cyclic GMPe0
- Outcome
- Ca(2+) signaling cascadee0
- Qualifier
- may be involvede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a BR-dependent elevation in cyclic GMP may be involved in the Ca(2+) signaling cascade initiated by this hormone”
t0“in Arabidopsis (Arabidopsis thaliana) cell cytosol”
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