2025-12-22 横浜市立大学
図1 フロリゲン・リレーのしくみ。イネのフロリゲンHd3aは葉で作られた後、茎の先端に位置する茎頂メリステム*2まで運ばれ、そこを花序メリステムへと切り替える。フロリゲンHd3aはメリステムの中央部分まで到達した後、そこで”第二のフロリゲン” OsFTL1の発現を活性化する。OsFTL1がメリステム全体に広がることで、花の発生が進む
<関連情報>
- https://www.yokohama-cu.ac.jp/res-portal/news/20251222tsuji.html
- https://www.yokohama-cu.ac.jp/res-portal/news/gjok7g0000003168-att/20251222tsuji.pdf
- https://www.science.org/doi/10.1126/sciadv.adv1424
フロリゲンとサイトカイニンシグナル伝達は、FLOWERING LOCUS T-LIKE1を拮抗的に制御し、イネの花序発達を促進するフロリゲンリレーを駆動する Florigen and cytokinin signaling antagonistically regulate FLOWERING LOCUS T-LIKE1 to drive a florigen relay that facilitates inflorescence development in rice
Moeko Sato, Yuki Sakamoto, Mari Tanaka, Jun Ito, […] , and Hiroyuki Tsuji
Science Advances Published:19 Dec 2025
DOI:https://doi.org/10.1126/sciadv.adv1424
Abstract
Plant reproductive development involves a series of transitions, with the shoot apical meristem (SAM) transitioning into the inflorescence meristem (IM) and then the floral meristem (FM). In rice (Oryza sativa), the florigens Heading date 3a (Hd3a) and RICE FLOWERING LOCUS T1 play central roles in these transitions. The plant hormones auxin and cytokinin shape the morphologies associated with each transition, but little is known about the factors that integrate florigen function with phytohormone signaling during these transitions. Here, we show that in rice, Hd3a activates the transcription of FT-LIKE1 (OsFTL1), which encodes a mobile FT-like protein that promotes the transition from the IM to the FM, whereas cytokinin signaling suppresses its transcription. We performed single-cell resolution three-dimensional imaging to elucidate the spatiotemporal distribution of Hd3a, cytokinin, and auxin signaling during the SAM-to-IM and IM-to-FM transitions, finding that Hd3a accumulation and cytokinin signaling occupy opposite domains in the IM. Hd3a accumulated at the center of the meristem and activated the OsFTL1 promoter, while OsFTL1 was present throughout the IM, suggesting that a “florigen relay” consisting of Hd3a from the leaves moves to the SAM and induces OsFTL1 expression within the SAM. We propose an antagonistic mechanism mediated by Hd3a and cytokinin that modulates the abundance of OsFTL1 and thus regulates reproductive development in rice.
