Molecular mechanisms and physiological roles of light-dispersal and dark-assembly reactions in chloroplast nucleoids

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K06710
• 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: Osaka Medical and Pharmaceutical University (2021-2023); Konan University (2020)
• Principal Investigator: Iwabuchi Kosei 大阪医科薬科大学, 医学部, 講師 (30583471)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: 核様体 / 光 / 遺伝子発現 / 光分散 / 暗集合 / ゼニゴケ / 葉緑体 / DNA

Outline of Final Research Achievements

In recent years, we have discovered that in the liverwort Marchantia polyorpha, the chloroplast nucleoids disperse throughout the chloroplast while forming multiple small speckles in bright light (photodispersion), and then gather in the center of the chloroplast in the dark (dark accumulation) as the speckles disappear. The photodispersion of the nucleoids occurs within three hours of light exposure. It has been postulated that the photodispersion of the nucleoid is accompanied by alterations in the higher-order structure of chloroplast DNA, and that there is a correlation between the photodispersion of the nucleoid and changes in the expression of chloroplast genes. Based on these observations, we propose a novel model in which the spatial rearrangement of chloroplast DNA accompanied by changes in the higher-order structure regulates the light-dependent expression of chloroplast genes.

Free Research Field

植物細胞生物学

Academic Significance and Societal Importance of the Research Achievements

葉緑体は光合成を行い糖質を作り出す重要な細胞小器官である。本研究により，核様体の空間配置が葉緑体遺伝子の発現調節に重要な役割を果たすことが分かってきた。光合成の調節機構を完全に解き明かすことは、人工光合成研究への応用だけでなく、植物の光合成能力の向上や今後変動しうる自然環境の中で植物が生き残るための機能を知る上でも重要である。本研究はこうした応用研究を支える重要な知見を提供したと考えている。