Elucidation of the light-dependent exothermic molecular mechanism that supports body temperature oscillations in cycad

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K07762
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Applied biochemistry
• Research Institution: University of Miyazaki
• Principal Investigator: Ito-Inaba Yasuko 宮崎大学, 農学部, 准教授 (80400191)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 発熱植物 / ソテツ / シアン耐性呼吸酵素 / ミトコンドリア / 光シグナル伝達 / 体温振動

Outline of Final Research Achievements

Cone thermogenesis is a widespread phenomenon in cycads. The most commonly proposed role for plant thermogenesis is to promote the emission of volatiles that may serve to attract pollinators. In this study, we investigated thermogenic properties and mitochondrial function/morphology in thermogenic cycad species, Cycas revoluta. Both male and female cones generated heat, but heat producing ability of male cones is more significant than that of female. Thermal image of the male cone was successfully taken by an infrared thermal camera, and this image was adopted on the cover by Plant Physiology (June 2019). Ultrastructural and biochemical analyses revealed that the existence of a population of mitochondria with a distinct morphology and with a high capacity of alternative respiratory pathway in thermogenic tissues, microsporophylls. These results suggest that distinctive mitochondrial morphology and AOX-mediated respiration in microsporophylls might play a role in cycad thermogenesis.

Free Research Field

植物生化学

Academic Significance and Societal Importance of the Research Achievements

ソテツ（Cycas revoluta）は、種子植物の中でも特に原始的な性質を持つことが知られており、九州南部や沖縄諸島を含む亜熱帯地域に広く安定的に分布する。これまで植物の発熱分子機構研究はサトイモ科などの被子植物を中心に展開されたが、本研究により、十分な発熱能力を有するC. revolutaは、発熱の基本的メカニズムを理解する上で今後重要な植物材料となり得ることを示した。将来的に、これらの植物を用いて花の発熱を支えるしくみを明らかとすれば、寒冷環境下における植物の成長遅延回避や、花における匂い成分の合成・飛散を助ける技術の開発につながることが期待できる。