Abstract
ABA plays an important regulatory role in seed germination because it inhibits the response to GA in aleurone, a secretory tissue surrounding the endosperm. Phosphatidic acid (PA) is a well-known intermediary in ABA signaling, but the role of diacylglycerol pyrophosphate (DGPP) in germination processes is not clearly established. In this study, we show that PA produced by phospholipase D (E.C. 3.1.4.4) during the antagonist effect of ABA in GA signaling is rapidly phosphorylated by phosphatidate kinase (PAK) to DGPP. This is a crucial fact for aleurone function because exogenously added dioleoyl-DGPP inhibits secretion of alpha-amylase (E.C. 3.2.1.1). Aleurone treatment with ABA and 1-butanol results in normal secretory activity, and this effect is reversed by addition of dioleoyl-DGPP. We also found that ABA decreased the activity of an Mg2+-independent, N-ethylmaleimide-insensitive form of phosphatidate phosphohydrolase (PAP2) (E.C. 3.1.3.4), leading to reduction of PA dephosphorylation and increased PAK activity. Sequence analysis using Arabidopsis thaliana lipid phosphate phosphatase (LPP) sequences as queries identified two putative molecular homologues, termed HvLPP1 and HvLPP2, encoding putative Lpps with the presence of well-conserved structural Lpp domains. Our results are consistent with a role of DGPP as a regulator of ABA antagonist effect in GA signaling and provide evidence about regulation of PA level by a PAP2 during ABA response in aleurone.
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Claims 9
Claim · model-written summary
PA is rapidly phosphorylated to DGPP by PAK during ABA antagonism of GA signaling.
- Taxon
- barley
.jpg?width=60)
Hordeum vulgaret0 - Gene
- phosphatidate kinase (PAK)e0
- Compound
- DGPPe0
- Outcome
- PA produced by phospholipase De0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“PA produced by phospholipase D (E.C. 3.1.4.4) during the antagonist effect of ABA in GA signaling is rapidly phosphorylated by phosphatidate kinase (PAK) to DGPP.”
t0“barley”
Claim · model-written summary
Added dioleoyl-DGPP inhibited alpha-amylase secretion.
- Taxon
- barleyHordeum vulgaret0
- Treatment
- dioleoyl-DGPPe0
- Gene
- alpha-amylasee0
- Outcome
- secretion of alpha-amylasee0
- Direction
- inhibitse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“exogenously added dioleoyl-DGPP inhibits secretion of alpha-amylase (E.C. 3.2.1.1)”
t0“barley”
Claim · model-written summary
ABA with 1-butanol allowed normal aleurone secretion.
- Taxon
- barleyHordeum vulgaret0
- Treatment
- ABA and 1-butanole0
- Outcome
- normal secretory activitye0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Aleurone treatment with ABA and 1-butanol results in normal secretory activity”
t0“barley”
Claim · model-written summary
Adding dioleoyl-DGPP reversed the normal secretory activity.
- Taxon
- barleyHordeum vulgaret0
- Treatment
- dioleoyl-DGPPe0
- Outcome
- this effecte0
- Direction
- reversede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“this effect is reversed by addition of dioleoyl-DGPP”
t0“barley”
Claim · model-written summary
ABA decreased PAP2 activity.
- Taxon
- barleyHordeum vulgaret0
- Treatment
- ABAe0
- Gene
- phosphatidate phosphohydrolase (PAP2)e0
- Outcome
- activity of an Mg2+-independent, N-ethylmaleimide-insensitive form of phosphatidate phosphohydrolase (PAP2)e0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“ABA decreased the activity of an Mg2+-independent, N-ethylmaleimide-insensitive form of phosphatidate phosphohydrolase (PAP2)”
t0“barley”
Claim · model-written summary
ABA reduced PA dephosphorylation.
- Taxon
- barleyHordeum vulgaret0
- Outcome
- PA dephosphorylatione0
- Qualifier
- reductione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“reduction of PA dephosphorylation”
t0“barley”
Claim · model-written summary
ABA increased PAK activity.
- Taxon
- barleyHordeum vulgaret0
- Gene
- PAKe0
- Outcome
- PAK activitye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increased PAK activity”
t0“barley”
Claim · model-written summary
Sequence analysis identified putative homologues HvLPP1 and HvLPP2.
- Taxon
- barleyHordeum vulgaret0
- Gene
- HvLPP1 and HvLPP2e0
- Outcome
- two putative molecular homologuese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“identified two putative molecular homologues, termed HvLPP1 and HvLPP2”
t0“barley”
Claim · model-written summary
Results support DGPP regulation of the ABA antagonistic effect in GA signaling.
- Taxon
- barleyHordeum vulgaret0
- Compound
- DGPPe0
- Outcome
- ABA antagonist effect in GA signalinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“DGPP as a regulator of ABA antagonist effect in GA signaling”
t0“barley”
The same questions in other papers
(+)-abscisic acid · physiology: photosynthesis · Hordeum vulgare (barley)Positive and negative results
2 papers in the same direction as this paper · 2 in the opposite direction
- positive
- positive
- negative
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