D-amino acids-induced root abscission in the water fern Azolla

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K06339
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 41050:Environmental agriculture-related
• Research Institution: University of the Ryukyus
• Principal Investigator: Yamasaki Hideo 琉球大学, 理学部, 教授 (40222369)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: D-アミノ酸 / 環境応答 / 絶滅危惧種 / 信号伝達系 / 精神薬 / Azolla

Outline of Final Research Achievements

Reactive Oxygen Species (ROS) and Reactive Nitrogen Species (RNS) have been proposed as universal signaling molecules in plant stress responses. There are a growing number of studies suggesting that hydrogen sulfide (H2S) or Reactive Sulfur Species (RSS) are also involved in plant abiotic as well as biotic stress responses. However, it is still a matter of debate as to how plants utilize those RSS in their signaling cascades. Here we demonstrate that D-cysteine is a novel candidate for bridging our gap in understanding. We tested five H2S chemical donors, Na2S, GYY4137, 5a, 8l and 8o, and found that 5a showed a significant abscission activity. Root abscission also occurred with the polysulfides Na2S2, Na2S3 and Na2S4. Rapid root abscission comparable to other known chemical inducers was observed in the presence of D-cysteine whereas L-cysteine showed no effect. We suggest that D-cysteine is a physiologically relevant substrate to induce root abscission in the water fern Azolla.

Free Research Field

環境生理学

Academic Significance and Societal Importance of the Research Achievements

生物のタンパク質はL-アミノ酸で構成されており、光学異性体のD-アミノ酸は細菌ペプチドグリカンの構成成分などが例外的に知られているだけだった。近年、哺乳類を含めた様々な生物でD-アミノ酸が検出されており、多様な生理機能を示すことが明らかになってきている。今回、アカウキクサで効果が見出されたD-セリンは、ヒトでは統合失調症等の脳疾患に深く関与していることが知られている。本研究の実施によって、アカウキクサの環境応答現象と、ヒト脳神経系とで機構上の類似点があることが薬理学的に示された。このことは、生物の外部刺激の検知応答メカニズムに共通性があることを示唆している。