Christine Zalejski

Publications (5)15.53 Total impact

• Article: Arabidopsis thaliana lipid phosphate phosphatase 2 is involved in abscisic acid signalling in leaves.

  Sophie Paradis, Ana Laura Villasuso, Susana Saez Aguayo, Régis Maldiney, Yvette Habricot, Christine Zalejski, Estela Machado, Bruno Sotta, Emile Miginiac, Emmanuelle Jeannette
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  ABSTRACT: Lipid phosphate phosphatases (LPPs, E.C. 3.1.3.4) catalyse the dephosphorylation of diacylglycerol pyrophosphate (DGPP) and phosphatidic acid (PA), which are secondary messengers in abscisic acid (ABA) signalling. In this study, we investigated the effect of ABA on the expression of AtLPP genes as they encode putative ABA-signalling partners. We observed that AtLPP2 expression was down-regulated by ABA and we performed experiments on Atlpp2-2, an AtLPP2 knockout mutant, to determine whether AtLPP2 was involved in ABA signalling. We observed that Atlpp2-2 plantlets contained about twice as much PA as the wild-type Col-0 and exhibited higher PA kinase (PAK) activity than Col-0 plants. In addition, we showed that ABA stimulated diacylglycerol kinase (DGK) activity independently of AtLPP2 activity but that the ABA-stimulation of PAK activity recorded in Col-0 was dependent on AtLPP2. In order to evaluate the involvement of AtLPP2 activity in guard cell function, we measured the ABA sensitivity of Atlpp2-2 stomata. The inhibition of stomatal opening was less sensitive to ABA in Atlpp2-2 than in Col-0. Watered and water-stressed plants of the two genotypes accumulated ABA to the same extent, thus leading us to consider Atlpp2-2 an ABA-signalling mutant. Taken together our observations show that AtLPP2 is a part of ABA signalling and participate to the regulation of stomatal movements.
  Plant Physiology and Biochemistry 03/2011; 49(3):357-62. · 2.84 Impact Factor
• Chapter: Diacylglycerol Pyrophosphate, A Novel Plant Signaling Lipid

  Emmanuelle Jeannette, Sophie Paradis, Christine Zalejski
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  ABSTRACT: Diacylglycerol pyrophosphate (DGPP) is a phosphorylated form of phosphatidic acid (PA) found in plants and yeast but not in mammals. DGPP is a minor lipid that accumulates transiently under various abiotic stresses and during biotic interactions. DGPP formation may be a way of attenuating PA content, but DGPP itself might also be a signaling lipid. DGPP is the product of the phosphorylation of PA catalyzed by PA kinase (PAK). Unfortunately, studies describing the role of PAK are limited as gene encoding PAK has not been identified yet. DGPP is dephosphorylated by lipid phosphate phosphatase (LPP) activity to produce PA. LPPs with DGPP phosphatase activity are found in a wide variety of organisms including bacteria, yeast, plants, and mammals. In Arabidopsis, four genes encoding LPPs have been identified, and a role for DGPP in abscisic acid signaling is becoming apparent.
  03/2009: pages 263-276;
• Article: Induction of abscisic acid-regulated gene expression by diacylglycerol pyrophosphate involves Ca2+ and anion currents in Arabidopsis suspension cells.

  Christine Zalejski, Sophie Paradis, Régis Maldiney, Yvette Habricot, Emile Miginiac, Jean-Pierre Rona, Emmanuelle Jeannette
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  ABSTRACT: Diacylglycerol pyrophosphate (DGPP) was recently shown to be a possible intermediate in abscisic acid (ABA) signaling. In this study, reverse transcription-PCR of ABA up-regulated genes was used to evaluate the ability of DGPP to trigger gene expression in Arabidopsis (Arabidopsis thaliana) suspension cells. At5g06760, LTI30, RD29A, and RAB18 were stimulated by ABA and also specifically expressed in DGPP-treated cells. Use of the Ca2+ channel blockers fluspirilene and pimozide and the Ca2+ chelator EGTA showed that Ca2+ was required for ABA induction of DGPP formation. In addition, Ca2+ participated in DGPP induction of gene expression via stimulation of anion currents. Hence, a sequence of Ca2+, DGPP, and anion currents, constituting a core of early ABA-signaling events necessary for gene expression, is proposed.
  Plant physiology 09/2006; 141(4):1555-62. · 6.53 Impact Factor
• Source

  Available from: Jean-Pierre Rona

  Article: Diacylglycerol pyrophosphate is a second messenger of abscisic acid signaling in Arabidopsis thaliana suspension cells.

  Christine Zalejski, Zongshen Zhang, Anne-Laure Quettier, Régis Maldiney, Magda Bonnet, Mathias Brault, Chantal Demandre, Emile Miginiac, Jean-Pierre Rona, Bruno Sotta, Emmanuelle Jeannette
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  ABSTRACT: In plants, the importance of phospholipid signaling in responses to environmental stresses is becoming well documented. The involvement of phospholipids in abscisic acid (ABA) responses is also established. In a previous study, we demonstrated that the stimulation of phospholipase D (PLD) activity and plasma membrane anion currents by ABA were both required for RAB18 expression in Arabidopsis thaliana suspension cells. In this study, we show that the total lipids extracted from ABA-treated cells mimic ABA in activating plasmalemma anion currents and induction of RAB18 expression. Moreover, ABA evokes within 5 min a transient 1.7-fold increase in phosphatidic acid (PA) followed by a sevenfold increase in diacylglycerol pyrophosphate (DGPP) at 20 min. PA activated plasmalemma anion currents but was incapable of triggering RAB18 expression. By contrast, DGPP mimicked ABA on anion currents and was also able to stimulate RAB18 expression. Here we show the role of DGPP as phospholipid second messenger in ABA signaling.
  The Plant Journal 05/2005; 42(2):145-52. · 6.16 Impact Factor
• Article: Induction of Abscisic Acid-Regulated Gene Expression by Diacylglycerol Pyrophosphate Involves Ca21 and Anion Currents in Arabidopsis Suspension Cells1(W)

  Christine Zalejski, S ophie Paradis, R egis Maldiney, Yvette Habricot, Emile Miginiac, Jean-Pierre Rona, Emmanuelle Jeannette