|Lanming Gou, Rongxue Zhang, Lei Ma1, Fugui Zhu, Jiangli Dong and Tao Wang. Multigene synergism increases the isoﬂavone and proanthocyanidin contents of Medicago truncatula. Plant Biotechnology Journal. DOI: 10.1111/pbi.12445|
Multigene synergism increases the isoﬂavone and proanthocyanidin contents of Medicago truncatula
Lanming Gou, Rongxue Zhang, Lei Ma1, Fugui Zhu, Jiangli Dong and Tao Wang
Plant Biotechnology Journal
Isoﬂavones and proanthocyanidins (PAs), which are ﬂavonoid derivatives, possess many health beneﬁts and play important roles in forage-based livestock production. However, the foliage of Medicago species accumulates limited levels of both isoﬂavones and PAs. In this study, biosynthesis of isoﬂavone and PA in Medicago truncatula was enhanced via synergy between soya bean isoﬂavone synthase (IFS1); two upstream enzymes, chalcone synthase (CHS) and chalcone isomerase (CHI); and the endogenous ﬂavanone 3-hydroxylase (F3H). Constitutive expression of GmIFS1 alone resulted in ectopic accumulation of the isoﬂavone daidzein and large increases in the levels of the isoﬂavones formononetin, genistein and biochanin A in the leaves. Furthermore, coexpression of GmIFS1 with GmCHS7 and GmCHI1A generally increased the available ﬂux to ﬂavonoid biosynthesis and resulted in elevated isoﬂavone, ﬂavone and PA contents. In addition, down-regulation of MtF3H combined with coexpression of GmIFS1, GmCHS7 and GmCHI1A led to the highest isoﬂavone levels (up to 2 lmol/g fresh weight in total). Taken together, our results demonstrate that multigene synergism is a powerful means to enhance the biosynthesis of particular ﬂavonoids and can be more broadly applied to the metabolic engineering of forage species.