Fig. 1

Functional analysis of BPLO by its co-expression with AtLup1 in yeast cells. GC–MS analysis was shown for the products from the yeast cells expressing AtLup1/BPLO yielding lupeol (LUP), betulin (BN), betulinic acid (BA), and the unknown products (peaks 2–3), and the cells expressing AtLup1 alone yielding lupeol and the unknown peak 1. The identities of LUP, BN and BA were confirmed with their corresponding chemical standards by comparing their mass fragmented products (Additional file 1: Figure S1). The identities of the peaks 1–3 were not determined due to the absence of their chemical standards, and their MS spectrums were shown in Additional file 1: Figure S2