Study on root greening response reveals regulatory mechanism of chloroplast development

2018 Fiscal Year Final Research Report

• Project/Area Number: 26711016
• Research Category: Grant-in-Aid for Young Scientists (A)
• Allocation Type: Partial Multi-year Fund
• Research Field: Plant molecular biology/Plant physiology
• Research Institution: Osaka Prefecture University (2018); The University of Tokyo (2014-2017)
• Principal Investigator: Kobayashi Koichi 大阪府立大学, 高等教育推進機構, 准教授 (40587945)
• Project Period (FY): 2014-04-01 – 2019-03-31
• Keywords: 葉緑体 / 光合成 / クロロフィル / 根 / 植物ホルモン / サイトカイニン

Outline of Final Research Achievements

Chloroplasts are the organelles that perform photosynthesis and play crucial roles in plant growth. However, regulatory mechanisms of chloroplast development remain largely elusive. My research group previously reported that removal of shoots from Arabidopsis seedlings induces chloroplast development and photosynthetic activation in roots. In this project, I attempted to reveal signaling pathways involved in the shoot removal-induced root greening response. The results demonstrate that shoot removal induces upregulation of a transcription factor GNL via activation of a cytokinin signaling pathway, thereby increases expression of nuclear- and plastid-encoded photosynthesis-associated genes and photosynthetic efficiency. This project further revealed that biosynthesis of major thylakoid membrane lipids before and at the onset of chloroplast biogenesis is essential for biosynthesis of chlorophylls and thylakoid-associated photosynthesis proteins.

Free Research Field

植物生理学

Academic Significance and Societal Importance of the Research Achievements

葉緑体は植物の生活環全体に大きく関わる細胞内小器官であり、植物の生きるしくみを明らかにするには葉緑体の発達制御機構の解明が不可欠である。報告者は、地上部の喪失に応答して葉緑体分化を誘導する情報伝達経路を明らかにした。さらに、解明した情報伝達経路を人工的に改変することで野生株の20倍ものクロロフィルを蓄積しかつ光合成能力も高い根を持つシロイヌナズナ形質転換体を作成することに成功した。本研究の成果は、葉緑体分化機構の全容を明らかにするだけでなく、植物の多様な生活様式や生存戦略の解明にも大きく貢献するもので、光合成能力や生存能力を高めた植物の開発にもつながる可能性を秘めている。