How a key gene pair guides flowering time in chrysanthemum
image: CmARF3–CmTCP7 model for promoting flowering in chrysanthemum “Jinba.” As short-day cycles accumulate, the expression of CmARF3 gradually increases, leading to the suppression of CmTCP7. This suppression weakens the interaction between CmTCP7 and CmFTL3/CmFDL1. Consequently, the CmFTL3–CmFDL1 complex can further promote the expression of CmCDM111L. In turn, CmCDM111L feedbacks to enhance CmFTL3 expression, forming a positive regulatory loop that reinforces floral induction under short-day conditions, ultimately accelerating flowering in chrysanthemum “Jinba.” The meaning of the arrows is as shown in the figure, with thicker arrows indicating stronger promoting or inhibiting effects. Image link: https://academic.oup.com/view-large/figure/521103855/uhaf095f7.tif
Credit: Horticulture Research
Photoperiod perception is a key external cue determining flowering time. Chrysanthemum, a typical short-day ornamental crop, requires precise flowering control for market scheduling. Although genes involved in the FT–FD pathway are known as flowering activators, upstream regulatory modules in chrysanthemum remain largely unclear. Auxin response factors and TCP proteins have been reported in Arabidopsis, but evidence in ornamental crops is limited. Understanding how these genes integrate environmental signals will support the development of flexible flowering strategies. Based on these challenges, it is necessary to investigate gene modules regulating the initiation of flowering.
A research team from Nanjing Agricultural University reported (DOI: 10.1093/hr/uhaf095) on May 23, 2025 in Horticulture Research that the gene CmARF3 promotes flowering by inhibiting the transcription factor CmTCP7, which delays floral transition. Suppression of CmTCP7 protein increases the activity of the CmFTL3–CmFDL1 complex and activates the floral identity gene CmCDM111L, advancing flowering under short-day conditions. The findings reveal a previously unknown upstream regulator of the FT–FD pathway and offer new tools for flowering-time improvement.
Expression analysis showed that CmTCP7 is downregulated during short-day induction, and plants with CmTCP7 silenced flowered 5–6 days earlier, confirming its inhibitory role. Yeast one-hybrid assays identified CmARF3 as an upstream gene. EMSA and ChIP-qPCR demonstrated that CmARF3 protein directly binds AuxRE motifs in the CmTCP7 promoter and suppresses its transcription. Overexpression of CmARF3 resulted in earlier flowering, whereas CmARF3 knockdown delayed flowering.
Protein interaction assays (BiFC, Co-IP, luciferase tests) further confirmed that CmTCP7 protein interacts with CmFTL3 and CmFDL1, reducing floral activation. When CmTCP7 inhibition is removed, the CmFTL3–CmFDL1 complex strongly induces CmCDM111L expression, initiating meristem identity. A positive feedback was also observed: CmCDM111L enhances expression of CmFTL3, reinforcing flowering progression. Regulatory cascade summary:Short day → ↑CmARF3 → ↓CmTCP7 protein activity → active CmFTL3–CmFDL1 complex → ↑CmCDM111L → flowering onset.
“Our study establishes CmARF3 and CmTCP7 as core regulators of the chrysanthemum flowering pathway,” the authors explained. “By inhibiting CmTCP7 protein, CmARF3 triggers activation of the CmFTL3–CmFDL1–CmCDM111L module, enabling earlier floral initiation. This mechanism provides breeding targets for adjusting flowering time and improving cultivation flexibility.” They noted that molecular manipulation of CmARF3 or CmTCP7 could support year-round production and customized flowering scheduling.
The CmARF3–CmTCP7 module offers a practical route for shortening flowering cycles without altering daylength management. Gene editing or marker-based selection targeting CmTCP7 repression may generate early-blooming cultivars suited for off-season and festival-driven markets. Breeding strategies modulating CmARF3 protein activity could further improve flowering reliability. The mechanism enriches understanding of photoperiod control in ornamentals and may inspire parallel studies in other short-day crops. This research lays molecular groundwork for precision flowering control in greenhouse production systems.
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References
DOI
Original Source URL
https://doi.org/10.1093/hr/uhaf095
Funding information
This work was supported by National Key R&D Program of China (2022YFF1003104), National Natural Science Foundation of China (31972451, 31930100), and a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions, PAPD, China.
About Horticulture Research
Horticulture Research is an open access journal of Nanjing Agricultural University and ranked number one in the Horticulture category of the Journal Citation Reports ™ from Clarivate, 2023. The journal is committed to publishing original research articles, reviews, perspectives, comments, correspondence articles and letters to the editor related to all major horticultural plants and disciplines, including biotechnology, breeding, cellular and molecular biology, evolution, genetics, inter-species interactions, physiology, and the origination and domestication of crops.