C‐glycosyltransferases (CGTs) are important enzymes that are responsible for the synthesis of the C‐glycosides of flavonoids and isoflavonoids. Flavonoid CGTs have been molecularly characterized from several plant species; however, to date, no gene encoding an isoflavonoid CGT has been reported from any plant species. A significant example of an isoflavonoid C‐glycoside is puerarin, a compound that contributes to the major medicinal effects of Pueraria lobata. Little is known about the C‐glucosylation that occurs during puerarin biosynthesis. One possible route for puerarin synthesis is via the C‐glucosylation of daidzein. This study describes the molecular cloning and functional characterization of a novel glucosyltransferase (PlUGT43) from P. lobata. Biochemical analyses revealed that PlUGT43 possesses an activity for the C‐glucosylation of daidzein to puerarin; it shows activity with the isoflavones daidzein and genistein, but displays no activity towards other potential acceptors, including flavonoids. To validate the in vivo function of PlUGT43, the PlUGT43 gene was over‐expressed in soybean hairy roots that naturally synthesize daidzein but that do not produce puerarin. The expression of PlUGT43 led to the production of puerarin in the transgenic soybean hairy roots, confirming a role for PlUGT43 in puerarin biosynthesis.

中文翻译：

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葛根中葛根素生物合成中C-葡萄糖基化的分子表征

C-糖基转移酶（CGTs）是重要的酶，负责合成类黄酮和异类黄酮的C-糖苷。类黄酮CGT已经从几种植物中进行了分子鉴定。然而，迄今为止，尚未从任何植物物种中报道编码异黄酮CGT的基因。异黄酮的显著例子Ç糖苷是葛根，化合物有助于主要的药用效果葛根。葛根素生物合成过程中发生的C-葡萄糖基化知之甚少。葛根素合成的一种可能途径是通过C黄豆苷元的葡萄糖基化。该研究描述了从一种新颖的葡糖基转移酶（PlUGT43）的分子克隆和功能表征葛根。生化分析表明，PlUGT43具有使大豆苷元C糖基化为葛根素的活性。它显示了与异黄酮黄豆苷元和染料木黄酮的活性，但对其他潜在受体（包括类黄酮）没有活性。为了验证PlUGT43的体内功能，PlUGT43基因在大豆毛根中过表达，而大豆毛根自然合成黄豆苷元，但不产生葛根素。PlUGT43的表达导致在转基因大豆毛状根中产生了葛根素，从而证实了PlUGT43在葛根素生物合成中的作用。