The circadian clock module LgPRR7-LgFKF1 negatively regulates flowering time in Luculia gratissima, a woody ornamental plant

Abstract

Photoperiod-dependent flowering is a critical trait in breeding for flowering time in woody ornamental plants. Circadian clocks are vital for the regulation of photoperiodic flowering in plants, but their molecular regulation pathways in woody perennials remain poorly explored. Here, we identified two circadian clock components LgPSEUDO-RESPONSE REGULATOR 7 (LgPRR7) and LgFLAVIN-BINDING KELCH REPEAT F-BOX 1 (LgFKF1) as key repressors of flowering in Luculia gratissima, a short-day woody ornamental plant with commercial potential. Levels of LgPRR7 and LgFKF1 transcripts exhibited photoperiodic responses and diurnal patterns. Ectopic overexpression of LgPRR7 or LgFKF1 in Arabidopsis thaliana accelerated flowering, whereas silencing LgPRR7 or LgFKF1 in L. gratissima accelerated flowering. Crucially, LgPRR7 directly interacts with LgFKF1, forming a self-reinforcing regulatory module LgPRR7-LgFKF1 to repress flowering in L. gratissima. Furthermore, the observed physical interactions among LgFKF1, LgCONSTANS-LIKE 12 (LgCOL12), and LgREPRESSOR OF ga1-3-LIKE 2 (LgRGL2) implied that they possibly formed a protein complex LgFKF1-LgCOL12-LgRGL2, bridging the circadian clock, photoperiod, and gibberellin signaling pathways to suppress downstream floral integrators. Intriguingly, silencing LgPRR7 and LgFKF1 extended the duration of L. gratissima flowering, a trait of horticultural significance. These results suggest the integration of multilayered environmental and endogenous signals in the regulation of flowering time. The LgPRR7-LgFKF1 module provides novel targets for molecular improvement to manipulate flowering time and duration in L. gratissima and other economically valuable woody ornamental plants. Our results also support the mediation of flowering convergence in short-day plants through the action of circadian clock genes.

Acknowledgments

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). The authors would like to thank Guangzhou Genedenovo Biotechnology Co., Ltd. for assisting in RNA sequencing.

Author Contributions

H.M., J.W., and Y.M. designed and supervised this study. X.L., Y.W., F.G., Z.W., Z.L., and Y.Z. performed the experiments. X.L. and Y.W. analyzed and interpreted the data. X.L., Y.W., H.M., Y.M., and J.W. wrote and revised the manuscript. All authors read and approved the final version of the manuscript.

Data availability

The raw data of RNA-seq from this study have been deposited in the NCBI Sequence Read Archive (SRA) database under accession no. PRJNA1109317. The de novo transcriptome has been deposited in the NCBI Transcriptome Shotgun Assembly (TSA) database under the accession no. GKUL00000000. The nucleotide sequences generated from this study have been deposited at GenBank under accession numbers MT822705 (the full-length cDNA sequence of LgPRR7), MT822704 (the full-length cDNA sequence of LgFKF1), PP782638 (the promoter sequence of LgPRR7), PP782639 (the promoter sequence of LgFKF1), PP782640 (the full-length CDS of LgCOL12), and PP782641 (the full-length CDS of LgRGL2), respectively.

Conflict of interest statement

The authors declare that there are no competing interests.

Supplementary data

Supplementary data is available at Horticulture Research online.

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