An L-arabinokinase is required for pollen development in higher plants

2018 Fiscal Year Final Research Report

• Project/Area Number: 26440168
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Morphology/Structure
• Research Institution: Akita Prefectural University
• Principal Investigator: Ueda Kenji 秋田県立大学, 生物資源科学部, 准教授 (80279504)
• Research Collaborator: HIRATSUKA Rie
• Project Period (FY): 2014-04-01 – 2019-03-31
• Keywords: 花粉形成 / L-アラビノキナーゼ / イネ / シロイヌナズナ / 糖代謝 / 突然変異体

Outline of Final Research Achievements

An L-arabinokinase-like CAP1 protein is required for pollen development in rice. In this study, we obtained recombinant CAP1 and several mutant CAP1 proteins using E. coli expression vector in bacterial cells, and analyzed these L-arabinokinase activity. The enzymatic activity was measured by the luciferase assay after an arabinokinase reaction. As a result, CAP1 is an actual L-arabinokinase, and the C terminal half of CAP1 was found to important for the L-arabinokinase activity. Next, we observed ultrastructure of cap1 mutation by electron microscopy, and examined CAP1 distribution using specific antiserum. CAP1 was detected on generative cell wall and intine in bicellular pollen by immune-electron microscopy using a specific antiserum. CAP1 is required for progression of bicellular pollen stage during pollen development. In addition, we examined two Arabidopsis homologs using T-DNA insertion lines, and found the AtARA2 is important for pollen development.

Free Research Field

植物生殖生理

Academic Significance and Societal Importance of the Research Achievements

本研究により、イネの花粉形成に必須なタンパク質CAP1がL-アラビノキナーゼであることが実証されたとともに、その活性には重要な領域を同定することができた。また、CAP1が二細胞花粉期の雄原細胞や栄養細胞の細胞壁に局在し、二細胞花粉期の進行に重要であることもわかった。さらに、広範囲の植物の花粉形成でCAP1類似タンパク質が重要な働きをしていることが明らかになった。これらの研究成果は、花粉形成を理解して植物の生殖機構を明らかにするための新しい知見であるとともに、人為的に花粉を不活化する花粉不稔剤の開発にも利用できる。花粉不稔剤は植物の品種改良や花粉症軽減などに貢献できる。