title: An Alternative Pathway for Formononetin Biosynthesis in Pueraria lobata.
abstract: The O-methylation is an important tailing process in Pueraria lobata isoflavone metabolism, but the molecular mechanism governing it remains not elucidated. This manuscript describes the mining of key O-methyltransferases (OMTs) involved in the process. Using our previously constructed P. lobata transcriptome, the OMT candidates were searched, extensively analyzed, and their functions were investigated by expression in yeast, Escherichia coli, or Glycine max hairy roots. Here, we report the identification of the key OMT gene responsible for formononetin production in P. lobata (designated as PlOMT9). PlOMT9 primarily functions as an isoflavone-specific 4'-O-methyltransferase, although it shows high sequence identities with isoflavone 7-O-methyltransferases. Moreover, unlike the previously reported OMTs that catalyze the 4'-O-methylation for formononetin biosynthesis at the isoflavanone stage, PlOMT9 performs this modifying step at the isoflavone level, using daidzein rather than 2,7,4'-trihydroxy-isoflavanone as the substrate. Gene expression analyses and metabolite profiling supported its proposed roles in P. lobata. Using the system of transgenic G. max hairy roots, the role of PlOMT9 in the biosynthesis of formononetin was further demonstrated in vivo.
authors.affiliation: CAS Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, Chinese Academy of Sciences, Hubei China.
authors.forename: Jia
authors.initials: J
authors.lastname: Li
authors.affiliation: CAS Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, Chinese Academy of Sciences, Hubei China.
authors.forename: Changfu
authors.initials: C
authors.lastname: Li
authors.affiliation: CAS Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, Chinese Academy of Sciences, HubeiChina; University of Chinese Academy of Sciences, BeijingChina.
authors.forename: Junbo
authors.initials: J
authors.lastname: Gou
authors.affiliation: CAS Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, Chinese Academy of Sciences, Hubei China.
authors.forename: Xin
authors.initials: X
authors.lastname: Wang
authors.affiliation: CAS Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, Chinese Academy of Sciences, HubeiChina; University of Chinese Academy of Sciences, BeijingChina.
authors.forename: Rongyan
authors.initials: R
authors.lastname: Fan
authors.affiliation: CAS Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, Chinese Academy of Sciences, Hubei China.
authors.forename: Yansheng
authors.initials: Y
authors.lastname: Zhang
keywords: 4′-O-methylation; O-methyltransferase; Pueraria lobata; hairy root; isoflavone