Analyses of molecular mechanisms in the synergid-endosperm fusion.

• Project/Area Number: 16H06173
• Research Category: Grant-in-Aid for Young Scientists (A)
• Allocation Type: Single-year Grants
• Research Field: Morphology/Structure
• Research Institution: Yokohama City University
• Principal Investigator: Maruyama Daisuke 横浜市立大学, 木原生物学研究所, 助教 (80724111)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Project Status: Completed (Fiscal Year 2018)
• Budget Amount: ¥23,530,000 (Direct Cost: ¥18,100,000、Indirect Cost: ¥5,430,000); Fiscal Year 2018: ¥7,280,000 (Direct Cost: ¥5,600,000、Indirect Cost: ¥1,680,000); Fiscal Year 2017: ¥7,800,000 (Direct Cost: ¥6,000,000、Indirect Cost: ¥1,800,000); Fiscal Year 2016: ¥8,450,000 (Direct Cost: ¥6,500,000、Indirect Cost: ¥1,950,000)
• Keywords: 花粉管 / 卵細胞 / 重複受精 / 細胞融合 / シロイヌナズナ / 助細胞 / 胚乳 / 助細胞胚乳融合 / 多花粉管拒否 / 遺伝学

Outline of Final Research Achievements

Cell-fusion between the persistent synergid and the endosperm (Synergid-Endosperm fusion, SE fusion) appears to be one of the important events in the cessation of pollen tube attraction in fertilized ovule. To elucidate molecular mechanism, we performed a pharmacological analysis and forward genetics.
Transcriptional or translational Inhibitors severely impaired induction of the SE fusion in fertilized ovules. Frequency of SE fusion also reduced by a treatment of roscovitine, an inhibitor of Cyclin-Dependent Kinases (CDKs). These data indicates an importances of post-fertilization de novo gene expression as well as mitotic entry in the induction of SE fusion.
In the forward genetics approach, we generated a reporter line that labels mitochondria and nucleus of the synergid cells with different colors, and induced point mutations by an EMS treatment. We isolated eight mutants that frequently showed a defect in SE fusion among 2,201 M1 individuals.

Academic Significance and Societal Importance of the Research Achievements

助細胞胚乳融合は被子植物の成長の過程でも珍しい細胞融合現象である。その仕組みの一端を示すとともに今後の詳しい解析につながる本研究は、植物が細胞を融合するために細胞壁や細胞膜をどのように制御するかを理解するために役立つ。また、花粉管誘引停止の制御を理解する基礎的な研究として、本研究成果は将来的に、卵細胞を2つの精細胞で受精させたり、卵細胞と中央細胞を別々の精細胞で受精させる技術の開発の発展に寄与すると期待される。

Research Products

• [Int'l Joint Research] Gregor Mendel Institute(オーストリア)
• [Int'l Joint Research] ケンタッキー大学(米国)
• [Int'l Joint Research] Gregor Mendel Institute(オーストリア)
• [Journal Article] A pharmacological study of Arabidopsis cell fusion between the persistent synergid and endosperm. (2018)
  • Author(s): Motomura K, Kawashima T, Berger F, Kinoshita T, Higashiyama T, Maruyama D.
  • Journal Title: J Cell Sci. Volume: 131 Issue: 2 Pages: 1-6
  • DOI: 10.1242/jcs.204123
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] RETINOBLASTOMA RELATED1 mediates germline entry in Arabidopsis. (2017)
  • Author(s): Zhao, X., Bramsiepe, J., Van Durme, M., Komaki, S., Prusicki, M.A., Maruyama, D., Forner, J., Medzihradszky, A., Wijnker, E., Harashima, H., Lu, Y., Schmidt, A., Guthorl, D., Logrono, R.S., Guan, Y., Pochon, G., Grossniklaus, U., Laux, T., Higashiyama, T., Lohmann, J.U., Nowack, M.K., Schnittger, A.
  • Journal Title: Science Volume: 356 Issue: 6336
  • DOI: 10.1126/science.aaf6532
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Spatiotemporal deep imaging of syncytium induced by the soybean cyst nematode Heterodera glycines (2017)
  • Author(s): Mina Ohtsu, Yoshikatsu Sato, Daisuke Kurihara, Takuya Suzaki, Masayoshi Kawaguchi, Daisuke Maruyama, Tetsuya Higashiyama
  • Journal Title: Protoplasma Volume: 印刷中 Issue: 6 Pages: 2107-2115
  • DOI: 10.1007/s00709-017-1105-0
  • NAID: 120006382262
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Pollen tube contents initiate ovule enlargement and enhance seed coat development without fertilization. (2016)
  • Author(s): Kasahara R., Notaguchi M., Nagahara S., Suzuki T., Susaki D., Honma Y., Maruyama D., Higashiyama T.
  • Journal Title: Science Advances Volume: 2 Issue: 10 Pages: 1-7
  • DOI: 10.1126/sciadv.1600554
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Journal Article] The end of temptation: the elimination of persistent synergid cell identity (2016)
  • Author(s): Daisuke Maruyama, Tetsuya Higashiyama
  • Journal Title: Current Opinion in Plant Biology Volume: 34 Pages: 122-126
  • DOI: 10.1016/j.pbi.2016.10.011
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Cell fusion and nuclear fusion in plants (2016)
  • Author(s): Daisuke Maruyama, Tetsuya Higashiyama
  • Journal Title: Seminars in Cell & Developmental Biology Volume: 60 Pages: 127-135
  • DOI: 10.1016/j.semcdb.2016.07.024
  • Peer Reviewed / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] Fertilization-independent Cell-fusion between the Synergid and Central Cell in the Polycomb Mutant (2016)
  • Author(s): Kazuki Motomura, Frederic Berger, Tomokazu Kawashima, Tetsu Kinoshita, Tetsuya Higashiyama, Daisuke Maruyama
  • Journal Title: Cell Structure and Function Volume: 41 Issue: 2 Pages: 121-125
  • DOI: 10.1247/csf.16010
  • NAID: 130005405450
  • ISSN: 0386-7196, 1347-3700
  • Peer Reviewed / Open Access / Int'l Joint Research / Acknowledgement Compliant
• [Presentation] Reception of pollen tube contents by the endosperm. (2018)
  • Author(s): Maruyama, D., Susaki, D., Higashiyama, T., Kinoshita, T.
  • Organizer: 25th International Conference on Sexual Plant Reproduction
  • Int'l Joint Research
• [Presentation] 助細胞は精細胞の放出先の位置を制御する微小流路として機能する (2017)
  • Author(s): 須崎 大地、東山 哲也、木下 哲、丸山 大輔
  • Organizer: 日本植物学会第81回大会
• [Presentation] 植物システムを支える生命の分岐点 (2016)
  • Author(s): 丸山大輔、東山哲也
  • Organizer: 日本細胞生物学会
  • Place of Presentation: テルサ京都（京都府京都市）
  • Year and Date: 2016-06-15
• [Book] Plant Germline Development (2017)
  • Author(s): Susaki, D., Maruyama, D., Yelagandula, R., Berger, F., Kawashima, T. Humana Press, New York, NY
  • Publisher: Humana Press, New York, NY
  • ISBN: 9781493972869