Biosynthesis and their mechanism of cyclic diarylheptanoids acting as signal compounds for actinorhizal symbiosis

2018 Fiscal Year Final Research Report

• Project/Area Number: 16H04951
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Wood science
• Research Institution: Shizuoka University
• Principal Investigator: Kawai Shingo 静岡大学, 農学部, 教授 (70192549)
• Co-Investigator(Kenkyū-buntansha): 米田 夕子 静岡大学, 農学部, 准教授 (90638595)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 環状ジアリールヘプタノイド / フランキア / アクチのリザル共生 / 生合成酵素遺伝子 / ポリケチド合成酵素 / 二重結合還元酵素

Outline of Final Research Achievements

The actinorhizal tree specifically biosynthesizes cyclic diarylheptonoids (CDHs) and utilizes them as symbiotic signaling agents with actinomycete Frankia to acquire a nitrogen source from Frankia. In this study, transcriptome analysis of enzyme genes involved in the biosynthesis of Alnus sioboldiana CDH was performed. As for the condensation enzyme, one polyketide synthase candidate gene was identified, but the expressed enzyme failed to catalyze the two-step condensation. Then, an intermediate of diketide CoA analogue was synthesized and used as a substrate, but the reaction did not proceed. On the other hand, for p-coumarate double bond reductase, two candidate genes were identified and heterologous proteins were expressed, but this enzyme could not reduce the substrate side chain.

Free Research Field

森林生物化学

Academic Significance and Societal Importance of the Research Achievements

本研究で対象とした環状ジアリールヘプタノイドは、窒素固定能を有する放線菌フランキアと根粒共生し、成長の早いアクチノリザル樹木に特異的に存在し、シグナル物質として機能する。したがって、この化合物の生合成機構と共生機構の解明は、森林の窒素循環に大きく関わり、二酸化炭素削減により地球温暖化を防止し地球を再生するための、樹木の光合成および生長に極めて大きい影響を与える窒素源の獲得に結びつく。また、健全な森林維持はもとより木質系バイオマスの持続的・循環的利用や、早生樹の作出など木質バイオマスの増産に結びつく極めて重要な課題である。