Plasmalemma abscisic acid perception leads to RAB18 expression via phospholipase D activation in Arabidopsis suspension cells.
Abscisic acid (ABA) plays a key role in the control of stomatal aperture by regulating ion channel activities and water exchanges across the plasma membrane of guard cells. Changes in cytoplasmic calcium content and activation of anion and outward-rectifying K(+) channels are among the earliest cellular responses to ABA in guard cells. In Arabidopsis suspension cells, we have demonstrated that outer plasmalemma perception of ABA triggered similar early events. Furthermore, a Ca(2+) influx and the activation of anion channels are part of the ABA-signaling pathway leading to the specific expression of RAB18. Here, we determine whether phospholipases are involved in ABA-induced RAB18 expression. Phospholipase C is not implicated in this ABA pathway. Using a transphosphatidylation reaction, we show that ABA plasmalemma perception results in a transient stimulation of phospholipase D (PLD) activity, which is necessary for RAB18 expression. Further experiments showed that PLD activation was unlikely to be regulated by heterotrimeric G proteins. We also observed that ABA-dependent stimulation of PLD was necessary for the activation of plasma anion current. However, when ABA activation of plasma anion channels was inhibited, the ABA-dependent activation of PLD was unchanged. Thus, we conclude that in Arabidopsis suspension cells, ABA stimulation of PLD acts upstream from anion channels in the transduction pathway leading to RAB18 expression.
Hallouin
Matthieu
M
Physiologie Cellulaire et Moléculaire des Plantes, Unité Mixte de Recherche Centre National de la Recherche Scientifique 7632, case 156, Université Pierre et Marie Curie (Paris VI), 4 place Jussieu, 75252 Paris cedex 05, France.
Ghelis
Thanos
T
Brault
Mathias
M
Bardat
Françoise
F
Cornel
Daniel
D
Miginiac
Emile
E
Rona
Jean-Pierre
JP
Sotta
Bruno
B
Jeannette
Emmanuelle
E
D000040:Abscisic Acid / Q000494:pharmacology*; D017360:Arabidopsis / Q000166:cytology / Q000201:enzymology / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics*; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D004789:Enzyme Activation / Q000187:drug effects; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D020962:Heterotrimeric GTP-Binding Proteins / Q000378:metabolism; D007473:Ion Channels / Q000187:drug effects; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D010739:Phospholipase D / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013379:Substrate Specificity; D010738:Type C Phospholipases / Q000378:metabolism; D020691:rab GTP-Binding Proteins / Q000235:genetics*
D029681:Arabidopsis Proteins; D007473:Ion Channels; C078703:rab18 protein, Arabidopsis; D000040:Abscisic Acid; D010738:Type C Phospholipases; D010739:Phospholipase D; D020962:Heterotrimeric GTP-Binding Proteins; D020691:rab GTP-Binding Proteins