Terpene synthase (TPS) involved in defensive oleoresin formation in conifers in response to insect attack or other injury. (2E)-geranyl diphosphate = (+)-car-3-ene + diphosphate Binds 3 Mg(2+) or Mn(2+) ions per subunit. Terpene metabolism; oleoresin biosynthesis. By jasmonic acid (MeJA). Belongs to the terpene synthase family. Tpsd subfamily.