Sesquiterpene synthase involved in the biosynthesis of volatile compounds (Ref.1). Mediates the conversion of (2E,6E)-farnesyl diphosphate (FPP) into beta-cadinene (Ref.1). Not active with geranyl diphosphate (GPP) and geranylgeranyl diphosphate (GGPP) as substrates (Ref.1). (2E,6E)-farnesyl diphosphate = beta-cadinene + diphosphate Binds 3 Mg(2+) or Mn(2+) ions per subunit. Secondary metabolite biosynthesis; terpenoid biosynthesis. Mostly expressed in leaves and, to a lower extent, in stems and xylem. The Asp-Asp-Xaa-Xaa-Asp/Glu (DDXXD/E) motif is important for the catalytic activity, presumably through binding to Mg(2+). Belongs to the terpene synthase family. Tpsa subfamily.