High NaCl (200 mM) increases the transcription ofphospholipase Dδ (PLDδ)in roots and leaves of the salt-resistant woody speciesPopulus euphratica. We isolated a 1138 bp promoter fragment upstream of the translation initiation codon ofPePLDδ. A promoter–reporter construct,PePLDδ-pro::GUS, was introduced into Arabidopsis plants (Arabidopsis thaliana) to demonstrate the NaCl-inducedPePLDδpromoter activity in root and leaf tissues. Mass spectrometry analysis of DNA pull-down-enriched proteins inP. euphraticarevealed that PeGLABRA3, a basic helix–loop–helix transcription factor, was the target transcription factor for binding the promoter region ofPePLDδ. The PeGLABRA3 binding toPePLDδ-pro was further verified by virus-induced gene silencing, luciferase reporter assay (LRA), yeast one-hybrid assay, and electrophoretic mobility shift assay (EMSA). In addition, thePeGLABRA3gene was cloned and overexpressed in Arabidopsis to determine the function of PeGLABRA3 in salt tolerance.PeGLABRA3-overexpressed Arabidopsis lines (OE1 and OE2) had a greater capacity to scavenge reactive oxygen species (ROS) and to extrude Na+under salinity stress. Furthermore, the EMSA and LRA results confirmed that PeGLABRA3 interacted with the promoter ofAtPLDδin transgenic plants. The upregulatedAtPLDδinPeGLABRA3-transgenic lines resulted in an increase in phosphatidic acid species under no-salt and saline conditions. We conclude that PeGLABRA3 activatedAtPLDδtranscription under salt stress by binding to theAtPLDδpromoter region, conferring Na+and ROS homeostasis control via signaling pathways mediated by PLDδ and phosphatidic acid.