Morphology maintenance of non-green plastids: characterization of the stromule-overproducing Arabidopsis mutants

2021 Fiscal Year Final Research Report

• Project/Area Number: 18K06314
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 44040:Morphology and anatomical structure-related
• Research Institution: University of the Ryukyus
• Principal Investigator: Itoh Ryuuichi 琉球大学, 理学部, 准教授 (50322681)
• Project Period (FY): 2018-04-01 – 2022-03-31
• Keywords: プラスチド

Outline of Final Research Achievements

Tubular structures called stromules are frequently formed in non-photosynthetic plastids of higher plants. In this study, we attempted to elucidate the mechanism of stromule formation by analyzing the Arabidopsis mutant suba1, which exhibits excessive stromule formation in pavement cells. The suba1 mutation in the causal gene TGD5 (encoding a lipid transport factor in the plastid envelope) was found to cause stromule formation in various non-mesophyll cells. Furthermore, it was found that while there are multifaceted effects, such as stromule hyperformation and poorer development of the internal membranous system in non-mesophyll tissues, there is only a slight effect on morphology and formation of mesophyll chloroplasts. These results suggest a fundamental difference in the mechanism of normal morphological maintenance between mesophyll chloroplasts and non-mesophyll plastids.

Free Research Field

植物細胞生物学

Academic Significance and Societal Importance of the Research Achievements

ストロミュールは、古くは19世紀後半から文献記載（スケッチ）がありながら（Schimper (1883) 等）、未だその形成機構は解明されていない。suba1変異体の原因遺伝子であるTGD5がコードするタンパク質は小胞体（ER）からプラスチドへの脂質輸送に関与していることから、①非葉肉プラスチドではER→プラスチド間脂質輸送が正常形態維持に必須であること、②葉肉細胞葉緑体と非葉肉プラスチドとでは、脂質合成経路の違いを反映して形態維持の仕組みも異なること、が示唆された。本研究成果は、140年来の謎であるストロミュール形成機構について「ERからの脂質輸送」という新たな角度から光を当てるものである。