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Diacylglycerol pyrophosphate inhibits the α‐amylase secretion stimulated by gibberellic acid in barley aleurone
Author(s) -
Racagni Graciela,
Villasuso Ana L.,
Pasquaré Susana J.,
Giusto Norma M.,
Machado Estela
Publication year - 2008
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.2008.01148.x
Subject(s) - aleurone , phosphatidic acid , diacylglycerol kinase , phosphatidate , biology , biochemistry , phospholipase d , endosperm , abscisic acid , phosphatase , lysophosphatidic acid , autotaxin , microbiology and biotechnology , diacylglycerol lipase , protein kinase c , signal transduction , phosphorylation , phospholipid , receptor , membrane , gene
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 α‐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 Mg 2+ ‐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.