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 abietadiene. The copalyl diphosphate (CPP) intermediate diffuses freely between the 2 active sites in the enzyme. Changes in reaction pH, but not salt concentration, influence the relative proportion of the major products of the enzyme, abitadiene, levopimaradiene and neoabitadiene. (2E,6E,10E)-geranylgeranyl diphosphate = (+)-copalyl diphosphate (+)-copalyl diphosphate = abieta-7,13-diene + diphosphate (+)-copalyl diphosphate = diphosphate + neoabietadiene Binds 3 Mg(2+) ions per subunit. Not inhibited by 13-cyclopropylidene or 16-methylidenegeranylgeranyl diphosphate. The copalyl diphosphate synthase activity is not susceptible to magnesium-dependent inhibition. Optimum pH is 7.2 with GGPP as substrate and 8.7 with CPP as substrate. Terpene metabolism; oleoresin biosynthesis. Monomer. By wounding. 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+). The N-terminus is blocked. The abietadiene synthase activity exhibits an absolute dependence on a divalent metal ion cofactor while the copalyl diphosphate synthase activity is not completely dependent. Belongs to the terpene synthase family. Tpsd subfamily.