Multifunctional diterpene synthase; part of the gene cluster that mediates the biosynthesis of the diterpene glucoside brassicicene C (PubMed:19097780). In the first step of the brassicicene C biosynthesis, the bifunctionnal diterpene synthase bsc8 that possesses both prenyl transferase and terpene cyclase activity, converts isopentenyl diphosphate and dimethylallyl diphosphate into geranylgeranyl diphosphate (GGDP) that is further converted into fusicocca-2,10(14)-diene, the first precursor for brassicicene C (PubMed:19097780). Fusicocca-2,10(14)-diene is then substrate of cytochrome P450 monooxygenase bsc1 for hydroxylation at the C-8 position (PubMed:19700326). Oxidation at C-16 position to aldehyde is then catalyzed by the cytochrome P450 monooyxygenase bsc7, yielding fusicocca-2,10(14)-diene-8-beta,16-diol (PubMed:19700326). Follows the isomerization of the double bond and reduction of aldehyde to alcohol catalyzed by the short-chain dehydrogenase/reductase bsc3 to yield the diol compound fusicocca-1,10(14)-diene-8 beta,16-diol (Probable). The next step is the oxidation at the C-3 position of fusicocca-2,10(14)-diene-8-beta,16-diol catalyzed by the alpha-ketoglutarate dependent dioxygenase bsc9, to produce a triol compound (PubMed:21299202). Methylation of the hydroxy group at position 16 is performed by the methyltransferase bsc6 (PubMed:19097780). 16-O-methylation is followed by oxidation at the C-13 position to ketone and an alkyl shift of the methyl group leads to brassicicene C (Probable). Although the probable acetyltransferase bsc4 is included in the gene cluster, no acetylation reactions are necessary for brassicicene C biosynthesis. However, the fact that brassicicene E, which is a structurally related compound having an acetoxy group at position 12, was previously isolated from another strain of A.brassicicola suggests that the ATCC 96836 strain might also produce a small amount of brassicicene E (Probable). geranylgeranyl diphosphate = diphosphate + fusicocca-2,10(14)-diene (2E,6E)-farnesyl diphosphate + isopentenyl diphosphate = (2E,6E,10E)-geranylgeranyl diphosphate + diphosphate Mycotoxin biosynthesis. In the N-terminal section; belongs to the terpene synthase family. In the C-terminal section; belongs to the FPP/GGPP synthase family.