Activation mechanisms of B2/B3 Raf kinases in plant stress responses

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K06680
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 44030:Plant molecular biology and physiology-related
• Research Institution: Saitama University
• Principal Investigator: Takezawa Daisuke 埼玉大学, 理工学研究科, 教授 (20281834)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 植物 / ストレス / 環境 / プロテインキナーゼ / アブシジン酸

Outline of Final Research Achievements

Phytohormone abscisic acid (ABA) plays a key role in stomata closure, osmostress acclimation, and vegetative and embryonic dormancy in plants. Group B2/B3 Raf protein kinases (B2/B3-Rafs) serve as positive regulators of ABA and osmostress signaling in both mosses and liverworts as well as in the angiosperm Arabidopsis thaliana. While P. patens has a single B3-Raf called ARK, specific members of B3-Rafs among six paralogs regulate ABA and osmostress signaling in A. thaliana, indicating functional diversification of B3-Rafs. It was also found that the liverwort Marchantia polymorpha, belonging to liverworts, has three paralogs of B3-Rafs, MpARK1, MpARK2 and MpARK3, and MpARK4 and MpARK5 with structural variations in the non-kinase region toward the N terminus of the polypeptide. These studies have shed light on the role of the regulatory domains located in the N-terminal domain on the regulation of these Raf kinases.

Free Research Field

植物生理学

Academic Significance and Societal Importance of the Research Achievements

高いレベルの環境ストレス耐性を持つコケ植物は、高い相同組み換え率やゲノム編集効率など、材料としても多くの利点がある。本研究で得られた成果は、被子植物にも保存される環境ストレス耐性の仕組みについても明らかにできると期待され、実際にコケ植物で明らかにされたB3-RAFの重要性は被子植物でも同様であることがのちに示された。こうしたアプローチは、シロイヌナズナなどのモデル系を用いた研究を補完するだけでなく、有用作物で未同定のストレス耐性関連因子の同定に寄与し、社会にも貢献しうる研究である。