Terpene synthase (TPS) involved in defensive oleoresin formation in conifers in response to insect attack (e.g. white pine weevil P.strobi) or other injury. (2E)-geranyl diphosphate = (+)-car-3-ene + diphosphate Binds 3 Mg(2+) or Mn(2+) ions per subunit. kcat is 0.06 sec(-1) with geranyl diphosphate as substrate. Terpene metabolism; oleoresin biosynthesis. By jasmonic acid (MeJA). Expressed only in resistant trees, not detected in genomic DNA of susceptible trees. Belongs to the terpene synthase family. Tpsd subfamily.