Mechanisms for maintenance of chloroplast genome stability by regulation of recombination

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K18588
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Genetics/Chromosome dynamics
• Research Institution: Institute of Physical and Chemical Research (2018); Rikkyo University (2016-2017)
• Principal Investigator: Odahara Masaki 国立研究開発法人理化学研究所, 環境資源科学研究センター, 研究員 (40460034)
• Research Collaborator: Nakamura Kensuke ; Oshima Taku ; Sekine Yasuhiko
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 葉緑体 / ゲノム安定性 / 相同組換え / 反復配列 / 次世代シークエンシング

Outline of Final Research Achievements

We analyzed the mechanisms for maintenance of chloroplast (cp) genome stability based on regulation of DNA recombination. We first introduced a pair of long repeats (>1 kb) into the Physcomitrella patens cpDNA, and observed that an efficient recombination was occurred between the introduced repeats. Next, we carried out comprehensive analysis of recombination products from cpDNA by deep sequencing and bioinformatics approaches, and showed that the identified recombination products were highly biased in terms of their locations and directions in RECA2 and RECG mutants. We analyzed RECX, a new candidate gene for regulation of recombination in chloroplast. RECX localized to both chloroplast and mitochondrial nucleoids, and interacted with chloroplastic RECA2. However, no significant phenotypes were observed in cpDNA as well as growth and morphology in RECX knockout or overexpression plants.

Free Research Field

植物分子遺伝学

Academic Significance and Societal Importance of the Research Achievements

本研究において、葉緑体ゲノムの不安定性をもたらす組換えに関して初めてゲノムスケールで解析を行い、ゲノムの構造との関係を明らかにすることができた。低頻度な組換えを核ゲノムあるいはバクテリアにおいてゲノムスケールで解析するのは技術的には難しく、本研究は組換えとゲノム安定性の関係を明らかにするためのモデルとなると考えられる。また、本研究で開発した次世代シークエンシングデータから組換えDNAを同定する情報学的手法は、オルガネラに限らず多くの生物のゲノム解析において有効であると考えられる。