The Molecular Cloning of 8-Epicedrol Synthase from Artemisia annua

A cDNA library was prepared from Artemisia annua, and a 129-bp fragment was amplified from this library using primers corresponding to sequences conserved in known dicot sesquiterpene synthases. A 1641-bp open reading frame that encoded a predicted protein 35–38% identical to dicot sesquiterpene synthases was cloned using this fragment as a hybridization probe. The gene product expressed in Escherichia coli cyclized farnesyl diphosphate to a 96:4 mixture of (−)8-epicedrol and cedrol. Neither cedrol epimer was detected by GC–MS in an A. annua extract prepared from the same specimen as the cDNA.