GC–MS analysis of the products formed in planta by transiently expressing TPS genes in Nicotiana benthamiana leaves. (a) Analysis of sesquiterpenes formed by TPS10 and TPS16. Nicotiana benthamiana leaves expressing GFP alone was used as a negative control. (b) Analysis of the formation of an unknown diterpene by co‐expressing TPS18 with CPT2. (c) Analysis of the formation of ent‐kaurene by expressing the full‐length and transit peptide deleted version (‘d’) of TPS genes. Products were extracted with methyl tert‐butyl ether (MTBE) and analysed as described in the ‘Materials and Methods’ section. Reaction products were identified by comparison of their mass spectra and retention indices with authentic standards and NIST libraries: 11, (Z,Z)‐farnesol; 21, α‐bisabolol; 22, δ‐cadinene; 23, unknown 4; 24, ent‐kaurene. Mass spectra and retention indices of the terpene products can be found in Supporting Information Fig. S3 and Table S2, respectively. CPS, ent‐copalyl diphosphate synthase; CPT, cis‐prenyltransferase; GGPPS, geranylgeranyl diphosphate synthase; KS, ent‐kaurene synthase; TPS, terpene synthase.