Involved in defensive oleoresin formation in conifers in response to insect attack or other injury. Involved in diterpene (C20) olefins biosynthesis. Bifunctional enzyme that catalyzes two sequential cyclizations of geranylgeranyl diphosphate (GGPP) to levopimaradiene. Levopimaradiene is the major products of the enzyme followed by abietadiene, neoabietadiene and palustradiene. No activity with geranyl diphosphate (GPP) or farnesyl diphosphate (FPP) as substrate. (2E,6E,10E)-geranylgeranyl diphosphate = (+)-copalyl diphosphate (+)-copalyl diphosphate = abieta-8(14),12-diene + diphosphate (+)-copalyl diphosphate = diphosphate + neoabietadiene Binds 3 Mg(2+) ions per subunit. Terpene metabolism; oleoresin biosynthesis. Expressed in young tissues such as flushing buds and green bark tissues. Lower levels in mature needles and bark. By methyl jasmonate. The Asp-Xaa-Asp-Asp (DXDD) motif is important for the catalytic activity in the class II active site relevant for the cyclization of GGPP. The Asp-Asp-Xaa-Xaa-Asp/Glu (DDXXD/E) motif is important for the catalytic activity in the class I active site, presumably through binding to Mg(2+). Belongs to the terpene synthase family. Tpsd subfamily.