IeCPS2 is potentially involved in the biosynthesis of pharmacologically active Isodon diterpenoids rather than gibberellin

► Three cDNAs from I. eriocalyx leaves putatively encoded copalyl diphosphate synthases. ► Recombinant IeCPSs convert geranylgeranyl diphosphate to copalyl diphosphate. ► IeCPS2 expression occurs in leaves, where Isodon ent-kaurane diterpenoids accumulate. ► Germinating seeds have neither detectable IeCPS2 transcripts nor Isodon diterpenoids. ► IeCPS1 is expressed in germinating seeds as well as in leaves.