Involved in the release of fatty acids from the oil body in germinating seedlings. Can hydrolyze triacylglycerols and diacylglycerols but not monoacylglycerols, phospholipids, galactolipids or cholesterol esters. SDP1 lipase activity is required to limit triacylglycerol accumulation in roots, leaves and stems, which are vegetative tissues. Functions synergistically with PDAT1 in regulating fatty acid flow from membrane lipid synthesis toward peroxisomal beta-oxidation through a transient triacylglycerol pool