Fig. 3

Characterization of T. wilfordii candidate oxidosqualene cyclases by transient expression in tobacco. a Two discs (Ø3 cm) of leaves expressing the indicated enzymes were extracted in 1 mL hexane (left panel) or 1 mL ethyl acetate (right panel) and analyzed by GC–MS either directly (left panel) or after solvent evaporation (of 0.15 mL aliquots) and trimethylsilyl cyanide derivatization (right panel). Major products were established by comparison of mass spectra and retention time to authentic standards (see also Additional file 1: Figure S1). b Comparison of the mass spectrum of friedelin standard with the spectrum of the main product of TwOSC4. c Structures and selected carbon numbering of the products