Abstract
The antagonism between gibberellins (GA) and abscisic acid (ABA) is an important factor regulating the developmental transition from embryogenesis to seed germination. In barley aleurone layers, the expression of genes encoding alpha-amylases and proteases is induced by GA but suppressed by ABA. It has been shown that an ABA-induced protein kinase, PKABA1, mediates the ABA suppression of alpha-amylase expression. Using a barley aleurone transient expression system, we have now localized the site of action of PKABA1 relative to other signal transduction components governing the expression of alpha-amylase. The expression of alpha-amylase can be transactivated by the transcription factor GAMyb, which is itself induced by GA. A truncated GAMyb containing the DNA binding domain but lacking the transactivation domain prevents the GA induction of alpha-amylase, further supporting the notion that GAMyb mediates the GA induction of alpha-amylase expression. Although ABA and PKABA1 strongly inhibit the GA induction of alpha-amylase, they have no effect on GAMyb-transactivated alpha-amylase expression. Using a GAMyb promoter--beta-glucuronidase construct, we also show that both ABA and PKABA1 repress the GA induction of GAMyb. In the slender mutant, GAMyb and alpha-amylase are highly expressed, even in the absence of GA. However, this constitutive expression can still be inhibited by ABA, PKABA1, or an inhibitor of cGMP synthesis. On the basis of these observations, we suggest that PKABA1 acts upstream from the formation of functional GAMyb but downstream from the site of action of the Slender gene product. Because PKABA1 inhibits the GA induction of the GAMyb promoter--beta-glucuronidase construct, it appears that at least part of the action of PKABA1 is to downregulate GAMyb at the transcriptional level.
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Claims 9
Claim · model-written summary
GAMyb transactivates alpha-amylase expression in barley aleurone cells.
- Taxon
- barley
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Hordeum vulgaree0 - Treatment
- transcription factor GAMybe1
- Outcome
- expression of alpha-amylasee1
- Direction
- transactivatede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“In barley aleurone layers”
e1“The expression of alpha-amylase can be transactivated by the transcription factor GAMyb”
Claim · model-written summary
A truncated GAMyb lacking the transactivation domain prevents GA induction of alpha-amylase.
- Taxon
- barleyHordeum vulgaree0
- Treatment
- truncated GAMybe2
- Outcome
- GA induction of alpha-amylasee2
- Direction
- preventse2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In barley aleurone layers”
e2“A truncated GAMyb containing the DNA binding domain but lacking the transactivation domain prevents the GA induction of alpha-amylase”
Claim · model-written summary
ABA and PKABA1 strongly inhibit GA induction of alpha-amylase in barley aleurone cells.
- Taxon
- barleyHordeum vulgaree0
- Treatment
- ABA and PKABA1e3
- Outcome
- GA induction of alpha-amylasee3
- Direction
- strongly inhibite3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In barley aleurone layers”
e3“Although ABA and PKABA1 strongly inhibit the GA induction of alpha-amylase, they have no effect on GAMyb-transactivated alpha-amylase expression”
Claim · model-written summary
ABA and PKABA1 have no effect on GAMyb-transactivated alpha-amylase expression.
- Taxon
- barleyHordeum vulgaree0
- Treatment
- ABA and PKABA1e3
- Outcome
- GAMyb-transactivated alpha-amylase expressione3
- Direction
- no effecte3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In barley aleurone layers”
e3“Although ABA and PKABA1 strongly inhibit the GA induction of alpha-amylase, they have no effect on GAMyb-transactivated alpha-amylase expression”
Claim · model-written summary
ABA and PKABA1 repress GA induction of GAMyb in a GAMyb promoter-beta-glucuronidase construct.
- Taxon
- barleyHordeum vulgaree0
- Treatment
- ABA and PKABA1e4
- Gene
- GAMybe4
- Outcome
- GA induction of GAMybe4
- Direction
- represse4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In barley aleurone layers”
e4“both ABA and PKABA1 repress the GA induction of GAMyb”
Claim · model-written summary
In the slender mutant, GAMyb and alpha-amylase are highly expressed even without GA.
- Taxon
- barleyHordeum vulgaree0
- Material
- slender mutante5
- Outcome
- GAMyb and alpha-amylasee5
- Direction
- highly expressede5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In barley aleurone layers”
e5“In the slender mutant, GAMyb and alpha-amylase are highly expressed, even in the absence of GA”
Claim · model-written summary
Constitutive expression in the slender mutant can still be inhibited by ABA, PKABA1 or a cGMP synthesis inhibitor.
- Taxon
- barleyHordeum vulgaree0
- Treatment
- ABA, PKABA1, or an inhibitor of cGMP synthesise6
- Outcome
- this constitutive expressione6
- Direction
- can still be inhibitede6
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In barley aleurone layers”
e6“this constitutive expression can still be inhibited by ABA, PKABA1, or an inhibitor of cGMP synthesis”
Claim · model-written summary
PKABA1 is suggested to act upstream of functional GAMyb formation but downstream of the Slender gene product.
- Taxon
- barleyHordeum vulgaree0
- Gene
- PKABA1e7
- Outcome
- formation of functional GAMybe7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In barley aleurone layers”
e7“we suggest that PKABA1 acts upstream from the formation of functional GAMyb but downstream from the site of action of the Slender gene product”
Claim · model-written summary
PKABA1 appears to downregulate GAMyb at the transcriptional level.
- Taxon
- barleyHordeum vulgaree0
- Gene
- GAMybe1
- Outcome
- downregulate GAMybe1
- Qualifier
- at the transcriptional levele1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In barley aleurone layers”
e1“it appears that at least part of the action of PKABA1 is to downregulate GAMyb at the transcriptional level”
The same questions in other papers
(+)-abscisic acid · molecular: expression · Hordeum vulgare (barley)Results differ
8 papers in the same direction as this paper · 6 in the opposite direction
- positive
- negative
- negative
11 papers more in this group
See all 15 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.