Sesquiterpene cyclase catalyzing mainly the production of beta-farnesene and alpha-bergamotene in equal amounts from farnesyl diphosphate (PubMed:19646721, PubMed:16418295, PubMed:21607717). Mediates also the biosynthesis of minor sesquiterpene hydrocarbons including alpha-muurolene, beta-bisabolene, zingiberene, sesquiphellandrene, sesquisabinene A, germacrene D, delta-cadinene, alpha-copaene and (E)-beta-caryophyllene (PubMed:16418295, PubMed:19646721). Involved in indirect defense by producing volatile signals attracting natural enemies of herbivores (PubMed:19646721, PubMed:16418295, PubMed:21607717). (2E,6E)-farnesyl diphosphate = (E)-beta-farnesene + diphosphate (2E,6E)-farnesyl diphosphate = alpha-copaene + diphosphate (2E,6E)-farnesyl diphosphate = (1S,5S,6R)-alpha-bergamotene + diphosphate (2E,6E)-farnesyl diphosphate = (-)-(E)-beta-caryophyllene + diphosphate (2E,6E)-farnesyl diphosphate = delta-cadinene + diphosphate (2E,6E)-farnesyl diphosphate = (+)-germacrene D + diphosphate (2E,6E)-farnesyl diphosphate = alpha-zingiberene + diphosphate (2E,6E)-farnesyl diphosphate = alpha-muurolene + diphosphate (2E,6E)-farnesyl diphosphate = (S)-beta-bisabolene + diphosphate (2E,6E)-farnesyl diphosphate = beta-sesquiphellandrene + diphosphate (2E,6E)-farnesyl diphosphate = diphosphate + sesquisabinene A Binds 3 Mg(2+) or Mn(2+) ions per subunit. Secondary metabolite biosynthesis; terpenoid biosynthesis. Monomer. Induced in leaves by herbivory (e.g. S.littoralis). The Asp-Asp-Xaa-Xaa-Asp/Glu (DDXXD/E) motif is important for the catalytic activity, presumably through binding to Mg(2+). Belongs to the terpene synthase family.