3.3 CsTPS1 and its AS forms can catalyze the formation of geraniol in vitro
To determine whether CsTPS1 and its AS formCsTPS1 -AS are involved in the formation of geraniol in tea plants, CsTPS1 and its AS splicing form CsTPS1 -ASwere expressed in E. coli Rosetta (DE3) cells, and the enzymatic activity of the recombinant proteins was assessed using GPP as substrate. The products of the enzymes were adsorbed by SPME during the reaction process, and GC–MS was used to analyze the enzyme products. The recombinant proteins of CsTPS1 and its AS splicing forms were involved in monoterpene formation when GPP was used as substrate (Figure 2). The main product was identified as geraniol based on commercial standards; however, (E) β-ocimene and (Z) β-ocimene were also observed (Figure 2C and 2D). No products were identified when FPP was used as substrate. These in vitro data suggest that CsTPS1 and its AS forms are involved in the formation of geraniol in tea plants.