Mechanisms for maintenance of chloroplast genome stability by regulation of recombination

• 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
• Project Status: Completed (Fiscal Year 2018)
• Budget Amount: ¥3,250,000 (Direct Cost: ¥2,500,000、Indirect Cost: ¥750,000); Fiscal Year 2018: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000); Fiscal Year 2017: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000); Fiscal Year 2016: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
• 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 / ヒメツリガネゴケ / 組換え / 散在性反復配列 / ミトコンドリア / RecA

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.

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。

Research Products

• [Journal Article] Stepwise evolution of supercomplex formation with photosystem I is required for stabilization of chloroplast NADH dehydrogenase-like complex: Lhca5-dependent supercomplex formation in Physcomitrella patens (2018)
  • Author(s): Kato Yoshinobu、Odahara Masaki、Fukao Yoichiro、Shikanai Toshiharu
  • Journal Title: The Plant Journal Volume: 96 Issue: 5 Pages: 937-948
  • DOI: 10.1111/tpj.14080
  • Peer Reviewed
• [Journal Article] RECX interacts with mitochondrial RECA to maintain mitochondrial genome stability (2018)
  • Author(s): Odahara, M. and Sekine, Y.
  • Journal Title: Plant Physiology Volume: 印刷中 Issue: 1 Pages: 300-310
  • DOI: 10.1104/pp.18.00218
  • Peer Reviewed
• [Journal Article] Holliday junction resolvases mediate chloroplast nucleoid segregation (2017)
  • Author(s): Kobayashi Y, Misumi O, Odahara M, Ishibashi K, Hirono M, Hidaka K, Endo M, Sugiyama H, Iwasaki H, Kuroiwa T, Shikanai T, Nishimura Y.
  • Journal Title: Science Volume: 356 Issue: 6338 Pages: 631-634
  • DOI: 10.1126/science.aan0038
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] MSH1 maintains organelle genome stability and genetically interacts with RECA and RECG in the moss Physcomitrella patens. (2017)
  • Author(s): Odahara, M., Kishita, Y., Sekine, Y.
  • Journal Title: Plant Journal Volume: 印刷中 Issue: 3 Pages: 455-465
  • DOI: 10.1111/tpj.13573
  • Peer Reviewed / Acknowledgement Compliant
• [Presentation] RECX Interacts with Mitochondrial RECA to Maintain Plant Mitochondrial Genome Stability (2018)
  • Author(s): 小田原真樹、関根康彦
  • Organizer: Gordon Research Conference ‘Mitochondria and Chloroplasts’
  • Int'l Joint Research
• [Presentation] Maintenance of mitochondrial genome stability by RECX (2017)
  • Author(s): 小田原真樹、関根靖彦
  • Organizer: International Congress of Plant Mitochondrial Biology 2017
  • Int'l Joint Research