Analysis of the integration mechanism of light and the circadian clock signals in the basal land plant Marchantia polymorpha

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K15818
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 44030:Plant molecular biology and physiology-related
• Research Institution: Kyoto University
• Principal Investigator: Inoue Keisuke 京都大学, 生命科学研究科, 助教 (20805931)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 光 / 概日時計 / 光周性 / 成長相転換 / 基部陸上植物 / ゼニゴケ

Outline of Final Research Achievements

In this study, we examined the mechanism for day-length perception in the basal land plant, the liverwort Marchantia polymorpha. We observed growth phase transitions under various diel conditions other than 24 hours (so-called T-cycles and NH-cycles), and found that the growth phase transition in M. polymorpha is generally determined by the ratio of the length of the light and dark periods. In addition, we confirmed that disturbance of endogenous rhythms by disruption of clock genes via CRISPR/Cas9-mediated genome editing or pharmacological analysis did not significantly affect growth phase transitions. Furthermore, we identified a set of genes, whose expression is dramatically induced in response to the length of the light period and found that there are various kinds of phytohormone biosynthetic genes. These results suggest that, unlike angiosperms, the basal land plant M. polymorpha has a day-length perception mechanism that is largely independent of the circadian clock.

Free Research Field

植物生理学

Academic Significance and Societal Importance of the Research Achievements

日長を認識して応答を制御する「光周性」は概日時計と光シグナルの相互作用を介した外的符号モデルによって制御されることが知られていたが、光周性研究は被子植物に限定されていたため、幅広い植物種にも外的符号モデルが成り立つのかは未明であった。本研究ではゼニゴケの日長応答が概日時計に大きく依存せず、明期と暗期の長さの比によって決まることを明らかにし、基部陸上植物が被子植物とは異なる日長認識機構を持つこと明らかにした。これまでは限られた植物種の解析によって日長認識機構のモデルが提唱されてきたが、本研究の成果は植物が多様な日長認識機構をもつ可能性を示しており、研究分野に新たな視点をもたらすと考えられる。