Fig. 1

Proposed pathway for breviscapine biosynthesis in E. breviscapus and construction of the apigenin-7-O-glucuronide producing platform strain. a Proposed pathway for breviscapine biosynthesis in E. breviscapus. Genes that have been reported are shown in blue and those which were identified in this study are shown in red. Abbreviations: apigenin-7-O-G, apigenin-7-O-glucuronide; 4CL, 4-coumaroyl-CoA ligase; C4H, cinnamate 4-hydroxylase; CHI, chalcone isomerase; CHS, chalcone synthase; FSII, flavone synthase II; F6H, flavone-6-hydroxylase; F7GAT, flavonoid-7-O-glucuronosyltransferase; PAL, phenylalanine ammonia lyase; UDPGDH, UDP-glucose dehydrogenase. b Construction of the apigenin-producing strain SC1. c HPLC analysis of the apigenin-7-O-glucuronide standard, the fermented products of the apigenin-7-O-glucuronide producing strain (SC1-Y33-EbF7GAT-EbUDPGDH) and the negative control strain (SC1-Y33). Y33 is the abbreviation of plasmid YCPlac33. d LC-MS analysis of apigenin-7-O-glucuronide in the fermented products of SC1-Y33-EbF7GAT-EbUDPGDH