Analysis of Ethylene-Dependent and Independent Mechanisms of Leaf Senescence Under Darkness

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K06232
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 44030:Plant molecular biology and physiology-related
• Research Institution: Kanazawa University (2023); Hiroshima University (2021-2022)
• Principal Investigator: Kozuka Toshiaki 金沢大学, 生命理工学系, 特任准教授 (20402779)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 老化 / エチレン / フィトクロム / クリプトクロム

Outline of Final Research Achievements

Plant senescence is a process of programmed cell death and an essential environmental response. Specifically, when photosynthetic organs, such as leaves, are exposed to prolonged periods of shade, senescence is induced. This leads to the rapid degradation of intracellular organelles and chlorophyll, causing the leaves to turn yellow. The degradation products are then reused as new nitrogen sources for the development of new organs. Plants recognize changes in the light environment through multiple photoreceptors, but the detailed mechanisms of senescence regulation downstream of these photoreceptors remain unclear. This study analyzed the mechanisms by which phytochromes and cryptochromes control ethylene synthesis. As a result, the transcriptional regulatory mechanism of ethylene synthesis enzyme genes by phytochrome B downstream factor PIF was elucidated, along with the signal transduction mechanism of cryptochrome 2, which suppresses leaf senescence in response to blue light.

Free Research Field

植物生理学

Academic Significance and Societal Importance of the Research Achievements

この研究は、フィトクロムとクリプトクロムがエチレン合成を制御し、植物の老化を調節するメカニズムを解明しました。特に、フィトクロムB下流因子PIFがエチレン合成酵素遺伝子を制御し、クリプトクロム2が青色光応答で葉老化を抑制することを明らかにしました。これにより、光環境を管理しエチレンシグナリングを調整することで、作物の老化を遅らせ、収穫量の増加や品質維持が可能となります。また、気候変動に強い作物の育成や収穫後の損失を減少させ、食糧安全保障の強化にも貢献します。この知見を活用することで、農業生産の最適化が図られます。