Apple flavor is characterized by combinations of ester compounds, which increase markedly during fruit ripening. The final step in ester biosynthesis is catalyzed by alcohol acyl transferases (AATs) that use coenzyme A (CoA) donors together with alcohol acceptors as substrates. The gene MpAAT1, which produces a predicted protein containing features of other plant acyl transferases, was isolated fromMalus pumila(cv. Royal Gala). TheMpAAT1gene is expressed in leaves, flowers and fruit of apple.