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.

Transcriptional Responses for Biosynthesis of Triterpenoids in Exogenous Inducers Treated Inonotus Hispidus Using RNA-Seq

“…This experimental study found that most of the triterpenoid monomers of I. hispidus are oleanane-type, and oleanane-type triterpenoid acids have pharmacological effects such as hypoglycemic, hypolipidemic, antitumor, etc. [ 20 ].…”

PgDDS Changes the Plant Growth of Transgenic Aralia elata and Improves the Production of Re and Rg3 in Its Leaves

“…The expression of PgDDS upstream and downstream genes in transgenic plants was examined, and the results showed that the expression levels of AeSQS and AeSE decreased, but the expression levels of AeFPS and AeCYP716A47 increased. Meanwhile, the expression levels of FPS, SQS, SE, and DDS increased in a Panax notoginseng cell overexpressing Pjβ-AS [16], which may be caused by the differences in metabolism between the cells and plantlets. PgDDS shares the same precursor, 2,3-oxidosqualene, with the other oxidosqualene cyclases (OSCs) in the saponin biosynthesis pathway (e.g., β-AS and CAS) (Figure 1), and because of the effect of expressing PgDDS in A. elata, the expression of AeCAS and Aeβ-AS was reduced in the transgenic lines in our study (Figure 4).…”

Ginsenosides in Panax genus and their biosynthesis

“…Silencing of DDS expression in transgenic P. ginseng resulted in a reduction of ginsenoside production to 84.5%, indicating that DDS played a vital role in ginsenoside biosynthesis 108 . Transgenic P. notoginseng cells with β-AS from P. japonicus ( Pjβ-AS ) produced C-IV and C-IVa, two OA-type saponins 119 , and transgenic Pjβ-AS rice produced OA-type sapogenin, demonstrating that β -AS was engaged in the biosynthesis of the precursor of OA-type ginsenosides 87 . Suppressing β-AS , PNY1 and PNY2 in P. ginseng hairy root resulted in the obvious decrease of OA-type ginsenoside (Ro) but the increase of dammarane-type ginsenosides (Rb1 and Rg1) and total ginsenosides 120 .…”