Oleanane-Type Saponins Biosynthesis in Panax notoginseng via Transformation of β-Amyrin Synthase Gene from Panax japonicus

Abstract

Oleanane-type saponins considered as the main medicinal ingredients in Panax japonicus are not found in Panax notoginseng. β-Amyrin synthase (βAS) was recognized as the first key enzyme in the biosynthetic branch of oleanane-type saponins. In this study, βAS gene from P. japonicus ( PjβAS) was transferred into P. notoginseng cells. Along with PjβAS expression in the transgenic cells, the expression levels of several key enzyme genes related to triterpenoid saponins biosynthesis and the content of P. notoginseng saponins were also increased. Two oleanane-type saponins, chikusetsusaponin IV and chikusetsusaponin IVa, contained in P. japonicus were first discovered in transgenic P. notoginseng cells. This study successfully constructed a biosynthetic pathway of oleanane-type saponins in P. notoginseng by introducing just one gene into the species. On the basis of this discovery and previous studies, the common biosynthetic pathway of triterpenoid saponins in Panax genus may be unified to some extent.