Possesses non-specific lipolytic acyl hydrolase (LAH) activity. Catalyzes the hydrolysis of the neutral lipids monogalactosyldiacylglycerol (MGDG), digalactosyldiacylglycerol (DGDG) and phosphatidylglycerol (PG), and less efficiently the polar lipids phosphatidylcholine (PC) and phosphatidylinositol (PI), but not the storage lipid triacylglycerol (TAG). May play a role in root development. Optimum pH is 7.0. Expressed specifically in roots and root hairs. The nitrogen atoms of the two glycine residues in the GGXR motif define the oxyanion hole, and stabilize the oxyanion that forms during the nucleophilic attack by the catalytic serine during substrate cleavage. Phosphorylated at Ser-399 by CPK3. Phosphorylation enhances PLP1 activity towards phosphatidylcholine. Decreased number of lateral roots. Belongs to the patatin family.