Elucidation of formation mechanism of adventitious embryos in Sargassaceous plants (Fucales, Phaeophyta) for new seaweed industry creation

Research Project

Project/Area Number	16K14976
Research Category	Grant-in-Aid for Challenging Exploratory Research
Allocation Type	Multi-year Fund
Research Field	Aquatic bioproduction science
Research Institution	Fisheries Research and Education Agency
Principal Investigator	Yoshida Goro 国立研究開発法人水産研究・教育機構, 瀬戸内海区水産研究所, グループ長 (40371968)
Research Collaborator	Mochida Kazuhiko Shimabukuro Hiromori
Project Period (FY)	2016-04-01 – 2019-03-31
Project Status	Completed (Fiscal Year 2018)
Budget Amount *help	¥3,250,000 (Direct Cost: ¥2,500,000、Indirect Cost: ¥750,000) Fiscal Year 2018: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000) Fiscal Year 2017: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000) Fiscal Year 2016: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Keywords	ホンダワラ類 / 増養殖 / 不定胚 / 室内培養 / 種苗生産 / 形態形成 / 生活環 / 有用海藻 / 種苗生産技術 / 海藻
Outline of Final Research Achievements	We have elucidated the induction conditions and mechanism of adventitious embryo formation on thalli of Sargassaceous plants(Fucales, Phaeophyta), which is observed as a specific phenomenon under culture. In Sargassum ilicifolium, a model species in this study, life cycle events such as morphogenesis and maturation were controlled by water temperature. Normal morphogenesis (main branch formation) of cultured juveniles were restrained at high temperature (24 ℃ or higher) and formation of adventitious embryos was induced on those restrained juveniles with high probability. Histological observation revealed that adventitious embryos are originated from the medullary layer cells of the leaves of the juveniles. Thalli derived from adventitious embryos have normal developmental potential and can be used as seedlings. Further, they also have a potential to produce adventitious embryos in a short period of time, which can be effective and useful for seedling production at industrial scale.
Academic Significance and Societal Importance of the Research Achievements	ホンダワラ類はヒジキやアカモク等の産業重要種を多数含み、増養殖の対象となっている。しかし、その種苗の確保は成熟期の有性生殖による配偶子の採取によっており、季節的な制約や労力が産業規模での展開の制約になっている。一方、本研究で提案した不定胚誘導とそれによる種苗生産は、室内の環境制御下で行うため、季節の限定が無いこと、3次元での生産が可能で水槽等の大規模施設は不要なこと等、従来法に比較し大きな利点があり、今後のホンダワラ類の産業利用を大幅に進展させうる可能性がある。また藻類学上においても、個体発生や形態形成、生活環の進行等の生物学的機構を解明するための重要な基礎的知見であると考えられる。