Plant Gene and Trait 2025, Vol.16, No.5, 194-205 http://genbreedpublisher.com/index.php/pgt 196 Emerging evidence suggests that post-translational regulation plays a crucial role in this pathway as well. RcSRR1 disrupts COP1-COregulation under red light conditions which results in RcCOinstability and subsequent changes in RcFT expression levels. The proteasome system degrades RcCO through a process that responds to different light qualities which are detected by red/far-red phytochrome signals. The system includes time and frequency components to control plant flowering behavior. The CONSTANS family proteins serve as essential regulators of light-dependent flowering according to Gendron and Staiger (2023) which directs most research on Rosa chinensis. 2.2 Rose-specific responses under long-day vs. short-day conditions The flowering behavior of R. chinensis remains constant under various photoperiods because it displays continuous flowering patterns regardless of long-day or short-day plant classification which applies to most temperate species. The system shows flexibility because it contains different CO-like and FT-like genes which express at distinct times (Sun et al., 2021). The CONSTANS-LIKE 4 (COL4) gene becomes the most abundant under short-day conditions to help replace RcCO function while sustaining RcFT activation (Lu et al., 2020). The continuous-flowering genotypes lack RoKSNfloral repressors which results in the loss of seasonal regulation that wild-type and early domesticated roses display (Soufflet-Freslon et al., 2021). The plant R. chinensis shows features which make it suitable for studying day-neutral flowering patterns. Experimental data also show cultivar-specific photoperiod sensitivity. Modern cultivars now show two different flowering responses to photoperiod extension because RcFT expression levels vary between them. The first group of cultivars flowers quickly when exposed to longer photoperiods because of increased RcFT expression. The second group of cultivars maintains their flowering ability under both long-day and short-day photoperiods. The breeding process has modified photoperiodic regulators through selection which resulted in commercial production having a broader flowering period. 2.3 Role of photoreceptors (PHYs, CRYs) in regulating flowering Research shows that far-red light speeds up flowering in ornamental plants when the daily light integral reaches a specific minimum value (Owen et al., 2018; Whitman et al., 2022). The research by Sun et al. (2021) shows that RcPHYAand RcCRY2 in R. chinensis stabilize RcCO protein when light is present which leads to increased RcFT expression. The process requires exact control through Phytochrome-interacting factors (RcPIFs) which work together with RcCO. The study shows that RcPIFs act to reduce RcCOactivity which leads to extended flowering time (Sun et al., 2021). The light spectrum functions as a vital component in this process. The activity of RcPHYAdepends on the ratio of red to far-red light but RcCRY2 responds to blue light. The knowledge gained through this research allows growers to use LED lighting for photoreceptor pathway control which leads to flowering regulation. The researchers evaluated the applications through protected cultivation systems which employed red-enriched light to speed up flowering and blue light to improve morphological precision (Sun et al., 2021). Research now shows that RcPHYAand RcCRY2 affect the strength of circadian outputs which indicates their function extends past their role in flowering initiation. R. chinensis achieves its complex flowering control system through its ability to connect light signal transduction pathways with circadian and hormonal networks. 3 Temperature-Mediated Flowering Regulation 3.1 Phenotypic responses to low, moderate, and high temperatures The plant development of Rosa chinensis shows different flowering patterns when exposed to low, moderate and high temperature conditions. Floral initiation experiences a delay when temperatures drop below 15°C and certain cultivars will completely stop flowering due to chilling stress. Plants experience color loss and fragrance changes and structural damage to their flowers when chilled according to Han et al. (2018) and Ouyang et al. (2022). The ideal temperature range for commercial rose cultivation spans from 18 to 25 degrees Celsius because it enables both flower development and produces premium flower quality. Plants that receive these specific growing conditions develop symmetrical flowers with vibrant colors and strong fragrances that stay fresh for longer periods. The combination of long-day photoperiods with moderate temperatures leads to better uniformity of flowers between branches which results in synchronized blooming (Figure 1) (Shin et al., 2023).
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