Figure 4.

Triterpene synthesis in tobacco leaves by heterologous expression of candidate triterpene synthases. (a) Chromatograms of typical LC‐MS analysis of the products of (iii) Malus × domestica OXIDOSQUALENE CYCLASE4 (MdOSC4), (iv) MdOSC5, and (v) MdOSC1 after transient expression in Nicotiana benthamiana. p19 was used as a negative control (ii) and mixed with authentic standards at 20 μg ml⁻¹ (1, lupeol; 2, β‐amyrin; 3, α‐amyrin) (i). Peak 4 on trace (iii) is the putative identification of germanicol. Compounds were identified and quantified on the basis of their mass spectral data (Supporting Information Figs S3, S4). Chromatograms are presented as selected ion plots of the m/z 409.8 [MH‐H₂O]⁺ ion. (b) Quantification of triterpene production by the various triterpene synthase genes in tobacco. Data show nmoles of triterpenes produced from 100 mg of extracted tissue (mean with SE; n = 4). Germanicol was quantified as β‐amyrin equivalents.