2023 Fiscal Year Final Research Report
Diazotrophic nitrogen fixation through aerial roots occurs in mangroves: implications for adaptation of mangrove plant growth to low-nitrogen tidal flats
| Project/Area Number |
21H02239
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Review Section |
Basic Section 40010:Forest science-related
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| Research Institution | National Institute for Environmental Studies |
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Principal Investigator |
Inoue Tomomi 国立研究開発法人国立環境研究所, 生物多様性領域, 主幹研究員 (80435578)
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| Co-Investigator(Kenkyū-buntansha) |
下野 綾子 東邦大学, 理学部, 准教授 (30401194)
高津 文人 国立研究開発法人国立環境研究所, 地域環境保全領域, 室長 (30514327)
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| Project Period (FY) |
2021-04-01 – 2024-03-31
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| Keywords | マングローブ / 通気組織 / 窒素固定 / 植物バクテリア相利共生 |
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| Outline of Final Research Achievements |
Mangrove trees maintain high levels of nitrogen fixation around their roots. The interior aerial space of mangrove roots, in which atmospheric gas is supplied through lenticels, could be efficient sites for nitrogen fixation. We measured tidal variations of partial pressure of N2 in root aerenchyma and conducted experiments using 15N2 as a tracer to track N2 movement through aerial roots of Avicennia marina.The nitrogenase activity and estimated nitrogen fixation through aerenchyma was higher in pneumatophores and absorbing roots than in cable roots. Positive correlations between root nitrogen contents and turnover rates of root nitrogen derived from N2 through aerenchyma suggested that the internal supply of N2 to diazotrophs could be the main source for nitrogen assimilation by roots. The aerial root structures could be an adaptation to survival in not only low-oxygen environments but also tidal flats with little plant-available nitrogen.
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| Free Research Field |
植物生理生態学
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| Academic Significance and Societal Importance of the Research Achievements |
マングローブ植物に特徴的に見られる地上根の形態は、多くの植物学者の興味の対象である。本研究の成果は、窒素不足になりやすい干潟に生育するマングローブ植物の窒素獲得機構を明らかするだけではなく、マングローブ植物の地上根の構造がもつ進化適応の背景を理解することにも貢献する。さらに、温暖化による海水面変動や気温の季節性の変化といった、将来起こり得る環境変化によって大きな影響を受ける可能性が高い、マングローブ植物と土壌環境との関係について、植物の生理生態学的反応の理解を深めることに貢献する。
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