Elucidation of the mechanism of petaloid sepal formation in polymorphic flowers of hydrangea

• Project/Area Number: 18K05628
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 39030:Horticultural science-related
• Research Institution: The University of Shiga Prefecture
• Principal Investigator: Uemachi Tatsuya 滋賀県立大学, 環境科学部, 准教授 (40243076)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Project Status: Completed (Fiscal Year 2020)
• Budget Amount: ¥4,420,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥1,020,000); Fiscal Year 2020: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000); Fiscal Year 2019: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000); Fiscal Year 2018: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
• Keywords: 花弁状がく片 / 弁化 / 観賞期間 / 装飾花 / 八重咲き / 手まり咲き / がく片 / アジサイ / トランスクリプトーム / ゲノム / 花弁化 / 花弁 / 園芸学 / 花器官

Outline of Final Research Achievements

Many dicotyledons with petaloid sepals have a long vase life and a unique beauty. Therefore, these are widely used as ornamental plants. In this study, we analyzed gene expression during flower formation using hydrangea, which has two types of flowers with different sepal shapes within its inflorescence, for the purpose of clarifying the mechanism of petaloid sepal formation in dicotyledons. As a result of comparing gene expression between decorative and non-decorative flowers, genes that are presumed to be involved in the phenotype of petal-like sepals were identified. From the functions of these genes, it was considered that the formation of petaloid sepals in hydrangea was promoted by the conversion of sepals into leaves rather than into petals.

Academic Significance and Societal Importance of the Research Achievements

花弁状がく片をもつ双子葉植物は，観賞期間が長く，独特な美しさを持つことが多く，観賞植物として広く利用されている．しかしこのような花弁状がく片が形成されるメカニズムは明らかとなっていない．本研究では，がく片の形状の異なる2種類の花を1つの花序内に着生するアジサイを用いて，がく片の花弁化に関わる遺伝子を調査した．その結果，花弁状がく片形成に関わることが推定される遺伝子が特定された．これらの成果は，スターチスやヘレボラスなどの観賞植物における花弁状がく片形成のメカニズムの解明に寄与するとともに，観賞期間の長い新たな観賞植物の育成に寄与するものと考えられる．

Research Products

• [Journal Article] Genome sequence of Hydrangea macrophylla and its application in analysis of the double flower phenotype (2020)
  • Author(s): Nashima Kenji、Shirasawa Kenta、Ghelfi Andrea、Hirakawa Hideki、Isobe Sachiko、Suyama Takuro、Wada Takuya、Kurokura Takeshi、Uemachi Tatuya、Azuma Mirai、Akutsu Midori、Kodama Masaharu、Nakazawa Yoshiko、Namai Kiyoshi
  • Journal Title: DNA Research Volume: 28 Issue: 1 Pages: 1-10
  • DOI: 10.1093/dnares/dsaa026
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Presentation] RNA-seq解析によるアジサイの装飾花と非装飾花での発現遺伝子の比較 (2020)
  • Author(s): 上町達也・小財将哉・前田彩子・小林良乃
  • Organizer: 園芸学会
• [Presentation] アジサイの装飾花形成時におけるSEPALLATA相同遺伝子の発現解析 (2019)
  • Author(s): 上町達也・前田彩子・小林良乃・川村優理子・竹内俊輝
  • Organizer: 園芸学会