PLD6 is a cardiolipin hydrolase present at the mitochondrial outer membrane required both for mitochondrial fusion and piRNA metabolic process. PLD6 acts by catalyzing the hydrolysis of cardiolipin (diphosphatidylglycerol) to form phosphatidate (phosphatidic acid or PA) at the mitochondrial outer membrane surface, promoting mitochondrial fusion. The production of phosphatidate also regulates the piRNA metabolic process by promoting recruitment and/or activation of components of the meiotic nuage, also named P granule, a critical step for primary biogenesis of piRNAs. It is required during spermatogenesis to repress transposable elements and prevent their mobilization via its role in the piRNA metabolic process, which mediates the repression of transposable elements during meiosis by forming complexes composed of piRNAs and Piwi proteins and govern the methylation and subsequent repression of transposons.