Molecular mechanisms of night-length recognition in photoperiodic flowering of chrysanthemum

2020 Fiscal Year Final Research Report

• Project/Area Number: 18H02194
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 39030:Horticultural science-related
• Research Institution: The University of Tokyo
• Principal Investigator: Higuchi Yohei 東京大学, 大学院農学生命科学研究科(農学部), 准教授 (00746844)
• Co-Investigator(Kenkyū-buntansha): 久松 完 国立研究開発法人農業・食品産業技術総合研究機構, 野菜花き研究部門, ユニット長 (00355710)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: キク / 光周性花成 / 絶対的短日植物 / 活性型フィトクロム / 概日時計

Outline of Final Research Achievements

To elucidate the mechanism of dark-time measurement in photoperiodic flowering of chrysanthemums, we generated over-expressor of constitutive active phytochrome B (BYH) in C. seticupse and performed comprehensive gene expression analysis by RNA-seq. The results showed that the expression of circadian clock genes, CsGI and CsPRR7, was up-regulated in BYH compared to the wild type. Overexpression of CsGI and CsPRR7 in C. seticuspe resulted in late flowering phenotype, suggesting that these genes may act as floral suppressors, and CsGI was found to be involved in the formation of photo-sensitive phase of anti-florigen induction. In addition, the expression of circadian clock genes in C. seticuspe was mainly set at dusk, suggesting the existence of a unique circadian clock mechanism in chrysanthemums.

Free Research Field

園芸科学

Academic Significance and Societal Importance of the Research Achievements

本研究は、短日植物において恒常的活性型フィトクロム過剰発現体を用い、花成応答ならびに活性型フィトクロムの標的となる概日時計遺伝子を解析した初の報告となり、キクやアサガオといった質的な短日応答性を示す植物が持つ暗期優性型の日長認識機構を理解する上で重要な知見を得ることができた。今後は、キクの電照栽培におけるより効率的な電照法の開発や、ゲノム編集等により開花期を最適化した新品種の育成に貢献できるものと期待している。