Light serves as a major environmental signal that influences growth, differentiation, and flowering in plants. In horticulture crops such as roses, adjusting light quality is widely used to optimize flowering, yet the effects of red light are particularly complex. Red light is known to suppress flowering in several plant species by affecting the CONSTANS (CO)–FLOWERING LOCUS T (FT) module, which forms the core of photoperiodic flowering regulation. However, in Rosa chinensis, a day-neutral woody species, the molecular basis by which red light delays blooming remained undefined. Because of these challenges, it is necessary to investigate how roses integrate red light signals to regulate flowering timing.
Researchers from Nanjing Agricultural University report new insights into how red light delays flowering in Rosa chinensis. The study, published (DOI: 10.1093/hr/uhaf025) in Horticulture Research in May 2025, reveals that the gene RcSRR1 plays a central role in suppressing flowering under red light. The authors show that RcSRR1 interacts with RcCSN5B to destabilize the flowering activator RcCO, thereby reducing RcFT expression and delaying bloom formation. The work identifies a new regulatory module involving RcFRSL3–RcSRR1–RcCSN5B that connects light perception with protein stability control in rose flowering.
The study demonstrated that roses exposed to red light flowered significantly later than those under white or blue light. Gene expression analyses revealed that only RcSRR1 was strongly upregulated by red light. Functional tests using virus-induced gene silencing showed that reducing RcSRR1 levels led to noticeably earlier flowering, especially under red light, confirming its role as a flowering repressor. Mechanistic experiments revealed that RcSRR1 physically interacts with the deneddylation regulator RcCSN5B. Normally, RcCSN5B promotes the deneddylation of the cullin protein RcCUL4, weakening the activity of the RcCRL4–COP1 ubiquitin ligase that targets RcCO. However, the binding of RcSRR1 to RcCSN5B interferes with this deneddylation process, strengthening the RcCRL4–COP1 complex and promoting RcCO degradation. Reduced RcCO protein availability subsequently suppresses RcFT expression and delays flowering. Upstream, the transcription factor RcFRSL3 directly binds the RcSRR1 promoter and represses its transcription under non-red-light conditions. Red light decreases RcFRSL3 expression, releasing RcSRR1 to activate the inhibition pathway. Together, this cascade explains how roses physiologically detect and respond to red-light environments.
“Our findings uncover a previously unknown signaling module that allows roses to modulate flowering according to light quality,” the authors explained. “By showing how RcSRR1 integrates red-light cues to influence CO protein turnover, we highlight a mechanism that connects light perception directly to the timing of floral induction. This work not only deepens our understanding of rose photobiology but also opens the door to targeted lighting strategies that could improve flowering uniformity and production efficiency in commercial cultivation.”
Understanding how red light delays flowering has significant practical implications for horticultural lighting management. Modern greenhouses increasingly rely on LED systems, and tuning spectral composition could allow growers to control flowering schedules more precisely. By suppressing or bypassing RcSRR1-mediated pathways, it may be possible to accelerate flowering during low-light seasons or synchronize flower production for market demand. Conversely, enhancing RcSRR1 activity could help maintain vegetative growth when extended blooming is undesirable. The newly identified RcFRSL3–RcSRR1–RcCSN5B module therefore provides valuable molecular targets for breeding, lighting optimization, and intelligent cultivation strategies.
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References
DOI
10.1093/hr/uhaf025
Original Source URL
https://doi.org/10.1093/hr/uhaf025
Funding information
This work was supported by the Natural Science Foundation of Jiangsu Province (BK20221008), NSFC (32372744, 32302594, 32172615, 32102418), the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions, and the ‘JBGS’ Project of Seed Industry Revitalization in Jiangsu Province (JBGS (2021)020), the China Postdoctoral Science Foundation (2023 T160325) and the Jiangsu Funding Program for Excellent Postdoctoral Talent (2022ZB344).
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.