Flowering time in plants is regulated by a complex interplay between environmental cues, internal biological clocks, and hormonal pathways. In annual model plants, these regulatory networks are well characterized, but in woody perennials—especially ornamental species—the underlying molecular mechanisms remain poorly understood. Growers often rely on artificial lighting or temperature manipulation to induce flowering, approaches that are costly and environmentally unsustainable. Moreover, most studies focus on when flowering begins, while the genetic control of flowering duration has received far less attention. Based on these challenges, there is a pressing need to investigate how circadian clock genes interact with hormonal signaling to regulate both flowering time and duration in woody ornamental plants.
Researchers from the Institute of Highland Forest Science, Chinese Academy of Forestry, together with collaborators from the Kunming Institute of Botany, Chinese Academy of Sciences, and the Yunnan Academy of Agricultural Sciences, report new insights into flowering regulation in Luculia gratissima, a commercially valuable woody ornamental species. The study, published (DOI: 10.1093/hr/uhaf110) in Horticulture Research, in April 2025, identifies two circadian clock genes—LgPRR7 and LgFKF1—that work together to suppress flowering under short-day conditions. By combining transcriptomic analysis, genetic manipulation, and protein interaction assays, the team demonstrates how this clock-controlled module integrates light signals with gibberellin hormone pathways to fine-tune floral development.
The researchers first compared plant development under short-day and long-day conditions and found that flowering initiation in L. gratissima was strictly photoperiod dependent. Transcriptome analysis revealed that two circadian clock genes, LgPRR7 and LgFKF1, were consistently downregulated during floral induction under short days, suggesting a repressive role. Functional experiments confirmed this hypothesis: overexpression of either gene accelerated flowering in Arabidopsis, while silencing them in L. gratissima led to earlier floral bud differentiation.
Protein interaction assays uncovered that LgPRR7 physically interacts with LgFKF1, forming a self-reinforcing regulatory module. Further experiments showed that LgFKF1 also interacts with LgCOL12—a photoperiod-related transcription factor—and LgRGL2, a repressor in the gibberellin signaling pathway. Together, these proteins form a multi-component complex that bridges circadian timing, light perception, and hormone signaling to suppress key floral integrator genes such as FT, LFY, and AP1.
Notably, silencing LgPRR7 and LgFKF1 not only advanced flowering but also significantly prolonged flowering duration by two to four days, revealing a dual regulatory role that is particularly valuable for ornamental horticulture.
“This work highlights how conserved circadian clock components can be repurposed in woody plants to achieve highly specific developmental outcomes,” said one of the study’s senior authors. “What is especially exciting is the discovery that manipulating clock genes does not simply shift flowering earlier or later—it can also extend the flowering period itself. This opens new opportunities for breeding ornamental plants that better match market demand while reducing reliance on artificial environmental control.”
The findings have immediate implications for ornamental plant breeding and sustainable horticultural production. By targeting clock-associated genes rather than external growing conditions, breeders may develop varieties with adjustable flowering schedules and longer display periods. This approach could lower energy consumption in greenhouses and improve the economic efficiency of year-round flower supply. Beyond ornamentals, the study also provides a comparative framework for understanding how circadian clock networks evolve differently in short-day and long-day species, offering insights that may inform crop improvement strategies in agriculture and forestry.
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References
DOI
10.1093/hr/uhaf110
Original Source URL
https://doi.org/10.1093/hr/uhaf110
Funding information
This work was supported by Major Science and Technology Special Program of Yunnan Science and Technology Department (Grant nos 202302AE090018, 202403AP140045), Yunnan Xingdian Talents-Special Selection Project for High-level Scientific and Technological Talents and Innovation Teams-Team Specific Project (202505AS350021), Forestry Science and Technology Project of Zhejiang Province (2025SY07), Yunnan Provincial Forestry Science and Technology Promotion Project (2023tsNo.01), Science and Technology Project for Rural Revitalization (202404BI090014), and Xing Dian Talent Support Program (YNWRQNBJ-2019-010).
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.