Abstract
The plant hormone abscisic acid (ABA) lead stomatal closure in guard cells along with productions of second messengers and modulation of ion channels. However, the ABA signal cascades in guard cells remain to be clairfied. Phospholipase D (PLD) hydrolyze phospholipid of the membrane and produce phosphatidic acid (PA) and their head group. In Arabidopsis, PLDα1 and PLDδ are involved in stress responses in plant. In this study, we analyzed pldα1 and pld δ single mutants and pldα1pldδ double mutant to clarify how PLD function in ABA signal transduction. The pldα1pldδ double mutation reduced PA production under drought condition compare to wild-type (WT) and single mutants. The pldα1pldδ impaired ABA-induced stomatal closure. The pldα1 and pldδ single mutants and pldα1pldδ double mutant as well as WT, PA and H2O2 induced stomatal closure. ABA induced ROS production and cytosolic alkalization in WT guard cells but not in the double mutant. These results suggest that both PLD α1 and PLD δ redundantly function in upstream of ROS production and cytosolic alkalization in ABA signaling of guard cells.
