Phosphorylates the second messenger diacylglycerol (DAG) to generate phosphatidic acid (PA), another important signaling molecule. PA is required for plant development and responses to abiotic stress and pathogen attack (Probable). May be involved in the accumulation of PA during cold stress (Probable). Involved in response to freezing stress by modulating the accumulation of PA. Exhibits high specificity for the unsaturated DAG analogs 1-stearoyl-2-arachidonoyl-sn-glycerol (1,2-SAG) and 1,2-dioleoyl-sn-glycerol (1,2-DOG). Exhibits high specificity for 1-palmitoyl, 2-oleoyl-sn-glycerol (1,2 POG), 1-stearoyl, 2-linoleoyl-sn-glycerol (1,2-SLG) and 1-oleoyl, 2-palmitoyl-sn-glycerol (1,2-OPG). Has almost no activity toward 1,2-dioctanoyl-sn-glycerol (1,2-DOCG), 1,2-dipalmitoyl-sn-glycerol (1,2-DPG), 1,2-dimyristoyl-sn-glycerol (1,2-DMG) and 1-oleoyl-2-acetyl-sn-glycerol (1,2-OAG). Functions together with DGK4 in male gametophyte development and biosynthesis of phosphatidylglycerol and phosphatidylinositol in the endoplasmic reticulum (ER). Involved in PA production for pollen grain growth, as well as leaf and root growth.
