Transcriptional factors related to flavonoid biosynthesis in the medicinal plant epimedium sagittatum (Berberidaceae)
Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, Hubei, China 430074.
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Herba epimedi, prepared from Epimedium species, is known as Horny Goat Weed and used as traditional Chinese medicine. Little is known about the molecular mechanism for the biosynthesis of bioactive compounds in Epimedium species, including icariin, epimedin A, epimedin B, and epimedin C. An EST dataset was generated by 454 GX-FLS sequencing using red-magenta fully expanded leaves and flowers of E. sagittatum Maxim. Consequently, 511, 102, and 383 consensus sequences were annotated and involved in flavonoid, carotenoid, and terpenoid pathways, respectively. Furthermore, these gene fragments and other flavonoid gene fragments isolated by SSH and homolog cloning were used as core fragments for cloning full-length genes involving flavonoid biosynthesis. Subsequently, the structural genes involved in flavonoid pathway were obtained and several full-length transcriptional factors, such as MYB, bHLH, and WD, were also isolated from Epimedium sagittatum. Expression analysis of these genes discovered a set of genes with positive and negative correlation with the accumulation of bioactive compound. Moreover, two MYB transcriptional factors have been functionally characterized for the biosynthesis of icarrin and anthocyanin. Both bioinformatic analysis and characterization of genes involved in the flavonoid biosyntheses pathway will facilitate the study toward uncovering the molecular mechanism of flavonoid accumulation in Epimedium species.
Key Words: Epimedium sagittatum, flavonoid biosynthesis；transcriptional factor；structure gene；