GC–MS analysis of terpenes

The analysis of terpene products (C₁₀–C₂₅) was performed as described previously (Falara et al., 2011). Briefly, 1 μl of sample was autoinjected into a Shimadzu QP‐2010 SE GC‐MS system equipped with a Rxi‐5Sil column (30 m length, 0.25 mm i.d., and 0.25 μm film thickness; Restek, Bellefonte, PA, USA). Analysis of isoprene was performed by directly injecting the SPME fibre into the Shimadzu QP‐2010 SE GC‐MS system equipped with the Rxi‐5Sil column. The analysis of prenyltransferase assay products was performed using an EC‐WAX column (30 m length, 0.32 mm i.d., and 0.25 μm film thickness; Grace, Columbia, MD, USA). The identification methods for each terpene compound are listed in Table S2. Details of GC–MS parameters can be found in Methods S1.