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. Produces (+)-sabinene from geranyl diphosphate, but has no activity with geranylgeranyl diphosphate or farnesyl diphosphate. (2E)-geranyl diphosphate = (1R,5R)-sabinene + diphosphate Binds 3 Mg(2+) ions per subunit. kcat is 0.89 sec(-1) with geranyl diphosphate as substrate. Terpene metabolism; oleoresin biosynthesis. Monomer. Up-regulated by methyl jasmonate. The Asp-Asp-Xaa-Xaa-Asp/Glu (DDXXD/E) motif is important for the catalytic activity, presumably through binding to Mg(2+). The highly resistant (H898) genotype and the highly susceptible (Q903) genotype differ in the nature and amount of the various terpenoids found in oleoresin. Belongs to the terpene synthase family. Tpsd subfamily.