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生命科学科・専攻
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神経分子機能研究室
発生生物学研究室
細胞遺伝学研究室
分子遺伝学研究室
植物発生生理学研究室
細胞生化学研究室
進化遺伝学研究室
神経生物学研究室
植物環境応答研究室
環境微生物学研究室
動物生態学研究室
植物生態学研究室
動物系統分類学研究室
植物系統分類学研究室
光合成複合微生物研究室
 
⇒応用生命科学領域
(大学院)
写真 植物発生生理学研究室
 被子植物の生活環においては、種子の発芽、幼植物から成熟個体への成長、花芽の形成、雌雄生殖器官の発生、重複受精、種子の形成など、さまざまな発生・生理現象がおきています。
 本研究室では、それらの中でも次世代の個体を残すことに密接に関連している、「受精、胚発生および種子形成」の過程に焦点を当てて研究を進めています。

[研究室メンバー]
教授 岡本龍史
助教 古川聡子
博士後期課程 Rahman MD Hassanur、渡辺 選子、戸田 絵梨香、Kasidit Rattanawong
博士前期課程 岩見 百華、古磯 成美、國分 巌、中平 織香、Tety Maryenti、出牛 稜也
卒業研究 赤坂 大輔、古野真由子、安冨 要、和田 美月
客員研究員 加藤 紀夫、内海 貴夫、鈴木莢花
[このHPは2018.4.3に更新しました]
教 員
教 授 岡本 龍史 e-mail
助 教 古川 聡子 e-mail
植物の受精を顕微鏡下で再現する
有性生殖を行う生物においては、卵(雌性配偶子)と精(雄性配偶子)が融合して受精卵が生じ、その受精卵が発生して次世代の個体になります。被子植物では、この配偶子融合が雌しべの奥底で起こることから、動物のように人工受精を行うことは簡単ではありません。しかしながら、我々はモデル植物であり、かつ、食糧としても重要なイネから卵細胞と精細胞を単離したのち、それらを電気的に融合させることにより受精卵を作出し、その受精卵を個体へと発生させる実験系 (in vitro 受精系)を確立することに成功し(図1、融合の瞬間)、植物の受精や受精卵発生の機構の解析を進めています。
画像
図1.イネ in vitro 受精系
休止状態にある卵細胞が、精細胞との融合によってどのように活性化し、発生を開始するのか
上記の植物発生学・生理学的に重要な疑問を明らかにしたいと考え、受精卵の活性化メカニズム、受精誘導性・抑制性遺伝子の機能解析、受精卵中における雌雄核の融合機構、受精卵発生における父親・母親ゲノムの役割、および受精卵の不等分裂機構などを研究のテーマにしています。図2は、イネ受精卵中における精核と卵核の融合の様子です。核融合後に、受精卵は活発に分裂します(受精卵の第一分裂過程)。
画像
図2.受精卵中における精核と卵核の融合過程(核の合一)
配偶子育種による新形質植物の作出
画像
図3.交雑受精卵からの胚性カルスと再生シュート
異種および同種の配偶子を任意の組み合わせで融合させることで、新しい形質をもつ植物(穀物)を作出する試みを進めています(特許出願済)。右の図3A はイネとコムギの交雑細胞由来の胚性細胞塊、図3B はイネとミナトカモジグサの交雑細胞由来の再生シュートです。また、異種間交雑細胞や倍数性細胞を用いて、異種間ゲノムの軋轢や雌雄ゲノムの機能差などの基礎生物学的な解析も行っています。
関連情報
・ 年報 【2017年度】【2016年度】【2015年度】【2014年度】【2013年度
最近の研究業績
  1. 原著論文 (original articles)
  2. Toda E., Ohnishi Y., Okamoto T. (2018) Effects of an imbalanced parental genome ratio on development of rice zygotes. J. Exp. Bot., in press
  3. Sukawa Y., Okamoto T. (2018) Cell cycle in egg cell and its progression during zygotic development in rice. Plant Reprod., in press, https://doi.org/10.1007/s00497-017-0318-x
  4. Yamamoto T., Yoshida Y., Nakajima K., Tominaga M., Gyohda A., Suzuki H., Okamoto T., Nishimura T., Yokotani N., Minami E., Nishizawa T., Miyamoto K., Yamane H., Okada K., Koshiba T. (2018) Antagonistic regulation of RSOsPR10 expression by jasmonate/ethylene and salicylate pathways is mediated by OsERF87 activator and OsWRKY76 Repressor, respectively, in rice roots. Plant Direct, in press
  5. Koiso N., Toda E., Ichikawa M., Kato N., Okamoto T. (2017) Development of gene expression system in egg cells and zygotes isolated from rice and maize. Plant Direct 1: e00010, DOI: 10.1002/pld3.10
  6. Bowman JL., Kohchi T., Yamato KT, 79 authors, Okamoto T., 27 authors, Schmutz J. (2017) Insights into land plant evolution garnered from the Marchantia polymorpha genome. Cell 171: 287–304. DOI: http://dx.doi.org/10.1016/j.cell.2017.09.030
  7. Okamoto T., Ohnishi Y., Toda E. (2017) Development of polyspermic zygote and possible contribution of polyspermy to polyploid formation in angiosperms. J. Plant Res., 130: 485-490. doi: 10.1007/s10265-017-0913-9
  8. Ohnishi Y. and Okamoto T. (2017) Nuclear migration during karyogamy in rice zygotes is mediated by continuous convergence of actin meshwork toward the egg nucleus. J. Plant Res. 130:339-348. doi: 10.1007/s10265-016-0892-2 
  9. Okamoto T. (2017) Analysis of proteins enriched in rice gamete. (2017) Methods Mol. Biol. 1669: 251-263.
  10. Park K., Kim Y., Vickers M., Park JS., Hyun Y., Okamoto T., Zilberman D., Fischer R., Feng X., Choi Y., Scholten S. (2017) DNA demethylation is initiated in the central cells of Arabidopsis and rice. PNAS, 113: 15138-15143. doi: 10.1073/pnas.1619047114.
  11. Toda E., Ohnishi Y. and Okamoto T. (2016) Electro-fusion of gametes and subsequent culture of zygotes. Bio Protocol, 6: e2074 DOI:10.21769/BioProtoc.2074
  12. Toda E. and Okamoto T. (2016) Formation of triploid plants via possible polyspermy. Plant Signaling & Behavior 11: e1218107. doi: 10.1080/15592324.2016.1218107.
  13. Toda E., Ohnishi Y. and Okamoto T. (2016) Development of polyspermic rice zygotes. Plant Physiol. 171: 206-214, doi: http://dx.doi.org/10.1104/pp.15.01953
  14. Matsumura T. and Okamoto T. (2016) Isolation of gametes from Brachypodium distachyon. Plant Biotech. 33: 39-43, http://doi.org/10.5511/plantbiotechnology.16.0123a
  15. Suzuki H, Yokawa K, Nakano S, Yoshida Y, Fabrissin I, Okamoto T, Baluška F and Koshiba T. (2016) Root cap-dependent gravitropic U-turn of maize root requires light-induced de novo auxin biosynthesis via YUC-pathway in root apex. J. Exp. Bot. 67: 4581-4591.
  16. Takeuchi K., Hasegawa H., Gyohda A., Komatsu S., Okamoto T., Okada K., Terakawa T., Koshiba T. (2016) Overexpression of RSOsPR10, a root-specific rice PR10 gene, confers tolerance against drought stress in rice and drought and salt stresses in bentgrass. Plant Cell, Tissue and Organ Culture (PCTOC) 127:35–46
  17. Ohnishi Y. and Okamoto T. (2015) Karyogamy in rice zygotes: Actin filament-dependent migration of sperm nucleus, chromatin dynamics, and de novo gene expression. Plant Signaling & Behavior, 10: e989021, DOI:10.4161/15592324.2014.989021
  18. Ohnishi Y. and Okamoto T. (2015) Microscopic observation, three-dimensional reconstruction, and volume measurements of sperm nuclei. Bio Protocol, 5: e1437, http://www.bio-protocol.org/e1437
  19. Ohnishi Y., Hoshino R. and Okamoto T. (2014) Dynamics of male and female chromatin during karyogamy in rice zygotes. Plant Physiol. 165: 1533–1543, doi: http://dx.doi.org/10.1104/pp.114.236059
  20. Abiko M., Furuta K., Yamauchi Y., Fujita C., Taoka M., Isobe T., and Okamoto T. (2013) Identification of proteins enriched in rice egg or sperm cells by single-cell proteomics. PLoS ONE 8(7): e69578, doi: 10.1371/journal.pone.0069578.
  21. Abiko M., Maeda H., Tamura K., Hara-Nishimura I. and Okamoto T. (2013) Gene expression profiles in rice gametes and zygotes: Identification of gamete-enriched genes and up- or down-regulated genes in zygotes after fertilization. J. Exp. Bot. 64: 1927–1940, doi: 10.1093/jxb/ert054.
  22. Okamoto T. (2011) In vitro fertilization with isolated rice gametes: production of zygotes and zygote and embryo culture. Methods Mol. Biol. 710: 17-27.
  23. Ohnishi T., Takanashi H., Mogi M., Takahashi H., Kikuchi H., Yano K., Okamoto T., Fujita M., Kurata N. and Tsutsumi N. (2011) Distinct gene expression profiles in egg and synergid cells of rice as revealed by cell type-specific microarrays. Plant Physiol. 155: 881-891.
  24. Takeuchi K., Gyohda A., Tominaga M., Kawakatsu M., Hatakeyama A., Ishii N., Shimaya K., Nishimura T., Riemann M., Nick P., Hashimoto M., Komano T., Endo A., Okamoto T., Jikumaru Y., Kamiya Y., Terakawa T., Koshiba T. (2011) RSOsPR10 expression in response to environmental stresses is regulated antagonistically by jasmonate/ethylene and salicylic acid signaling pathways in rice roots. Plant Cell Physiol. 52: 1686–1696.
  25. Okamoto T. (2010) Gamete fusion site on the egg cell and autonomous establishment of cell polarity in the zygote. Plant Signaling & Behavior, 5: 1464-1467.
  26. Nakajima K., Uchiumi T. and Okamoto T. (2010) Positional relationship between the gamete fusion site and the first division plane in the rice zygote. J. Exp. Bot. 61: 3101-3105.
  27. Sato A., Toyooka K., and Okamoto T. (2010) Asymmetric cell division of rice zygotes located in embryo sac and produced by in vitro fertilization. Sex Plant Reprod. 23: 211–217.
  28. Uchiumi T. and Okamoto T. (2010) Rice fruit development is associated with an increased IAA content in pollinated ovaries. Planta 232: 579-592.
  29. Takanashi, H., Ohnishi, T., Mogi, M., Okamoto, T., Arimura, S and Tsutsumi N. (2010) Studies of mitochondrial morphology and DNA amount in the rice egg cell. Curr. Genet. 56:33-41.
  30. Wang S. and Okamoto T. (2009) Involvement of polypyrimidine tract-binding protein (PTB) related proteins in pollen germination in Arabidopsis. Plant Cell Physiol. 50: 179-190.
  31. Kranz E., Hoshino Y. and Okamoto T. (2008) In vitro fertilization with isolated higher plant gametes. Methods Mol. Biol. 427: 51-69.
  32. Uchiumi T., Uemura I. and Okamoto T. (2007) Establishment of an in vitro fertilization system in rice (Oryza sativa L.) Planta 226:581-589.
  33. Uchiumi T., Shinkawa T., Isobe T. and Okamoto T. (2007) Identification of the major protein components of rice egg cells. J Plant Res. 120: 575-579.
  34. Uchiumi T., Komatsu S., Koshiba T. and Okamoto T. (2006) Isolation of gametes and central cells from Oryza sativa L. Sex Plant Reprod. 19: 37-45.
  35. Okamoto T., Scholten S., Lörz H. and Kranz E. (2005) Identification of genes that are up- or down-regulated in the apical or basal cell of maize two-celled embryos and monitoring their expressions during zygote development by a cell manipulation- and PCR-based approach. Plant Cell Physiol. 46: 332-338.
  36. Okamoto,T., Higuchi K., Shinkawa T., Isobe T., Lörz H., Koshiba T. and Kranz E. (2004) Identification of major proteins in maize egg cells . Plant Cell Physiol. 45: 1206-1212.
  37. Okabe T., Sutoh K., Okamoto T. Minamikawa T. and Yamauchi D. (2004) Hormonal regulation of expression of the gene for pod storage protein in common bean plants. Plant Biotec. 21: 215-223.
  38. Okamoto T., Shimada T., Hara-Nishimura I., Nishimura M. and Minamikawa T. (2003) C-terminal KDEL sequence of a vacuolar KDEL-tailed cysteine proteinase (SH-EP) is essential for vacuolar transport of SH-EP and formation of KDEL-vesicle (KV). Plant Physiol. 132: 1892-1900.
  39. Okamoto T., Toyooka K. and Minamikawa T. (2001) Identification of a membrane-associated cysteine protease (MCP) with possible dual roles in the endoplasmic reticulum and protein storage vacuole. J. Biol. Chem. 276: 742-751.
  40. Minamikawa T., Toyooka K., Okamoto T., Hara-Nishimura I. and Nishimura M. (2001) Degradation of ribulose 1,5-bisphosphate carboxylase/oxygenase by vacuolar enzymes of senescing French bean leaves: Immunocytochemical and ultrastructural observations. Protoplasma. 218: 144-153.
  41. Taneyama M., Okamoto T., Yamane H. and Minamikawa T. (2001) Involvement of Gibberellins in Expression of a Cysteine Proteinase (SH-EP) in Cotyledons of Vigna mungo Seedlings. Plant Cell Physiol. 42: 1290-1293.
  42. Toyooka K., Okamoto T. and Minamikawa T. (2001) Cotyledon cells of Vigna mungo seedlings utilize at least two distinct autophagic machineries for degradation of starch granules and cellular components. J. Cell Biol. 154: 973-982.
  43. Tsuru-Furuno A., Okamoto T. and Minamikawa T. (2001) Isolation of a putative receptor for KDEL-tailed cysteine proteinase (SH-EP) from cotyledons of Vigna mungo seedlings. Plant Cell Physiol. 42: 1062-1070.
  44. Toyooka K., Okamoto T. and Minamikawa T. (2000) Mass transport of a KDEL-tailed cysteine proteinase (SH-EP) to protein storage vacuole by ER-derived vesicle is involved in protein mobilization in germinating seeds. J. Cell Biol. 148: 453-463.
  45. Okamoto, T., T. Minamikawa, C. Edward, V. Vakharia and E. Herman (1999) Posttranlational removal of the carboxyterminal KDEL of the cysteine protease SH-EP occurs prior to maturation of the enzyme. J. Biol. Chem. 274: 11390-11398.
  46. Okamoto T., Yuki A., Mitsuhashi N. and Minamikawa T. (1999) Asparaginyl endopeptidase (VmPE-1) and autocatalytic processing synergistically activate the vacuolar cysteine proteinase (SH-EP). Eur. J. Biochem. 264: 223-32.
  47. Okamoto T. and Minamikawa T. (1999) Molecular cloning and characterization of Vigna mungo processing enzyme 1 (VmPE-1), an asparaginyl endopeptidase possibly involved in post-translational processing of a vacuolar cysteine endopeptidase (SH-EP). Plant Mol. Biol. 39: 63-73.
  48. Hosokawa T., Okamoto T. and Minamikawa T. (1999) Characterization of serine endopeptidases in cotyledons of germinated Vigna mungo seeds. J. Plant Res. 112: 217-221.
  49. Zhong P-Y., Yamauchi D., Okamoto T., Okabe T. and Minamikawa T. (1999) Synthesis and degradation of a 28-kDa pod storage protein in French bean (Phaseolus vulgaris) plants. Planta 210: 72-79.
  50. Okamoto T., Miura-Izu Y., Ishii S. and Minamikawa T. (1996) Asparaginyl endopeptidase in developing and germinating legume seeds: Immunological detection and quantitation. Plant Sci. 115: 49-57.
  51. Taneyama T., Okamoto T., Yamauchi D. and Minamikawa T. (1996) Development of endo-peptidase activity in cotyledons of Vigna mungo seedlings: Effects of exogenously applied end-products and plant hormones. Plant Cell Physiol. 37: 19-26.
  52. Yamauchi D., Terasaki Y. Okamoto T. and Minamikawa T. (1996) Promoter regions of cysteine endopeptidase genes from legumes confer germination-specific expression in transgenic tobacco seeds. Plant Mol. Biol. 30: 321-329.
  53. Okamoto T. and Minamikawa T. (1995) Purification of a processing enzyme (VmPE-1) that is involved in post-translational processing of a plant cysteine endopeptidase (SH-EP). Eur. J. Biochem. 231: 300-305.
  54. Okamoto T., Nakayama H. Seta K. Isobe T. and Minamikawa T. (1994) Posttranslational processing of a carboxy-terminal propeptide containing a KDEL sequence of plant vacuolar cysteine endopeptidase (SH-EP). FEBS Lett. 351: 31-34.
  55. 総説 (reviews)
  56. Okamoto T., Ohnishi Y. and Toda E. (2017) Development of polyspermic zygote and possible contribution of polyspermy to polyploid formation in angiosperms. J. Plant Res, in press
  57. Okamoto, T. (2014) Gene and protein expression profiles in rice gametes and zygotes: a cue for understanding the mechanisms in gametic and/or early zygotic development of angiosperms. In “Sexual Reproduction in Animals and Plants”, Eds, Sawada H., Inoue H., Iwano M., Springer, pp369-382.
  58. Okamoto T. (2006) Transport of proteases to the vacuole: ER export by-passing golgi? D.G. Robinson ed. The Plant Endoplasmic Reticulum. Plant Cell Monogr. 4: 125-139.
  59. Okamoto T. and Kranz E. (2005) In vitro fertilization - a tool to dissect cell specification from a higher plant zygote. Embryology of Seed Plants: Then and Now. Professor Panchanan Maheshwari Centenary Special Issue of Current Science. 89: 1861-1869.
  60. Okamoto T. and Kranz E. (2005) Major proteins in plant and animal eggs. Acta Biologica Cracoviensia, Series Botanica, 47, 17-22.
  61. Kranz E., Hoshino Y., Okamoto T. and Scholten S. (2004) Double fertilization in vitro and transgene technology. Plant Biotechnology and Molecular Markers. Srivastava, P.S.; Narula, Alka and Srivastava, Sheela (eds), Kluwer Academic Publishes, Dordrecht, pp. 31-42.
  62. Okamoto T. and Minamikawa T. (1998) A vacuolar cysteine endopeptidase (SH-EP) that digests seed storage globulin: characterization, regulation of gene expression, and posttranslational processing. J. Plant Physiol. 152: 675-682.
  63. Okamoto T. and T. Minamikawa (1997) A cysteine endopeptidase (SH-EP) in geminatedVigna mungo seeds; post-translational processing and intracellular transport. Basic and Applied Aspects of Seed Biology. Kluwer Academic Publishers. pp563-568.
  64. その他出版物
  65. 岡本龍史 (2017) in vitro 受精系と育種、「受精後雑種障壁研究の育種利用に向けて」、育種学研究、 Vol. 19 (No. 1) p. 35-36.
  66. 井川智子、東山哲也、岡本龍史 (2014)「第7章:被子植物の受精2:花粉管の伸長とガイダンス、配偶子の融合、核の合一」、動植物の受精学:共通機構と多様性、澤田均編、化学同人、pp103-118.
  67. 岡本龍史 (2009) 受精の生理、種子の科学とバイオテクノロジー、原田久也他/編、学会出版センター、pp25-27.
  68. 岡本龍史 (2006) 胚発生、植物ホルモンの分子細胞生物学、小柴共一・神谷勇治/編、講談社、pp122-134.
  69. 岡本龍史、内海貴夫(2006) In vitro 受精系を用いた胚発生研究法、植物の生長調節 41:75-86.
  70. 岡本龍史 (2002) KDEL小胞を介した液胞タンパク質の輸送系.植物細胞工学シリーズ17: 42-50.
  71. 岡本龍史、南川隆雄 (2002) 発芽種子の貯蔵物質分解機構:液胞加水分解酵素・KDEL小胞・オートファジー.化学と生物40: 790-798.
  72. 特許
  73. 植物に物質を導入する方法 特願2017- 15371
  74.    発明者:加藤紀夫、岡本龍史、大西由之佑、古磯成美、木羽隆敏、戸田絵梨香
  75.    出願人:日本たばこ産業、理化学研究所、首都大学東京
  76. 植物に物質を導入する方法 特願2016-70288
  77.    発明者:加藤紀夫、岡本龍史
  78.    出願人:日本たばこ産業、首都大学東京
  79. 植物配偶子の電気融合による同質および異質倍数性植物の作出 特願2014-195165
  80. 発明者:岡本龍史、大西由之佑、戸田絵梨香
  81.   出願人:首都大学東京
©2015 Department of Biological Sciences, Tokyo Metropolitan University