Comprehensive understanding of the regulatory mechanisms underlying triterpenoid biosynthesis in licorice

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K07754
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Applied biochemistry
• Research Institution: Osaka University
• Principal Investigator: SEKI HIKARU 大阪大学, 工学研究科, 准教授 (30392004)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: トリテルペノイドサポニン / 生合成 / 転写制御因子 / シトクロムP450 / bHLH

Outline of Final Research Achievements

Plants produce a vast array of useful small molecules called secondary metabolites. Glycyrrhizin is a triterpenoid saponin produced only in roots and stolons of Glycyrrhiza species (licorice) in the legume family. It is widely used as medicines and natural sweetener. Besides glycyrrhizin, licorice also produces soyasaponins. Biosynthesis of saponins is strictly regulated as it is often limited in the specific organs or tissues, or induced in response to external or internal stimuli. However regulatory mechanism of triterpenoid biosynthesis is largely unknown. The objective of this research is to identify transcription factors (TFs) regulating saponins biosynthesis in licorice. We identified a bHLH-type TF able to activate transcription of soyasaponin biosynthetic genes. We also identified some candidate TFs potentially regulate glycyrrhizin biosynthetic genes.

Free Research Field

植物二次代謝

Academic Significance and Societal Importance of the Research Achievements

植物は多様な有用低分子化合物（植物二次代謝産物）を生産する。トリテルペノイドサポニン(サポニン）は多くの生薬の活性成分や天然甘味成分として知られる植物成分の一グループである。肝庇護薬、抗炎症剤、甘味料原料として用いられるサポニンであるグリチルリチンを生産する薬用植物カンゾウ（甘草）の根は漢方処方の7割以上に配合されている。本研究で得られた、サポニン生合成の制御機構に関する知見は有効成分含量が高い植物系統の作出や栽培条件の確立において有用な情報である。