Cloning and characterization of a cDNA encoding beta-amyrin synthase involved in glycyrrhizin and soyasaponin biosyntheses in licorice

An oxidosqualene cyclase cDNA, termed GgbAS1, was isolated from cultured ce lls of licorice (Glycyrrhiza glabra) by heterologous hybridization with cDN A of Arabidopsis thaliana LUP1 lupeol synthase. The yeast transformed with an expression vector containing the open reading frame of GgbAS1 produced b eta -amyrin, indicating that GgbAS1 encodes beta -amyrin synthase involved in the glycyrrhizin and soyasaponin biosyntheses in licorice. Northern blot analysis showed that the level of beta -amyrin synthase mRNA was drastical ly changed in the cultured licorice cells, whereas the mRNA level of cycloa rtenol synthase was relatively constant.