Serrano-Bueno, G. | bioRxiv Science

bioRxiv2026

SELF-PRUNING 5G interplays with age and gibberellin pathways downstream of SlCOL1 to orchestrate photoperiodic tomato flowering

Tomato (Solanum lycopersicum) is classified as a day-neutral plant, whereas its wild relatives exhibit delayed flowering under long day (LD) conditions due to higher activity of the SELF-PRUNING 5G (SP5G). In Arabidopsis thaliana, CONSTANS (CO) activates FLOWERING LOCUS T (FT), a homolog of SP5G, but whether and how CO integrates with SP5G in tomato flowering was unclear. Here, we demonstrate that SlCOL1 (the tomato CO homolog) delays flowering by directly activating SP5G in a PHYTOCHROME B1 (PHYB1)-dependent manner. Importantly, genetic and molecular analyses combining a photoperiod-responsive tomato line carrying the wild SP5G allele from S. pennellii, together with SlCOL1 and flowering-pathway mutants, revealed synergistic crosstalk among the photoperiodic SlCOL1-SP5G module, age-dependent pathway (mediated mainly by the microRNA156-SlSBP module), gibberellin (GA) pathway, and SINGLE FLOWER TRUSS (SFT) pathway. Mechanistically, we show that SP5G forms a complex with miR156-targeted SlSBP13 to directly regulate SFT expression, and that GA may interfere with SP5G activity. Together, these findings revealed a coordinated network that integrates multiple flowering signals to modulate both shared and pathway-specific targets. Our findings provide a significant advance in understanding the molecular regulation of tomato flowering and offer promising avenues for breeding strategies optimized for diverse environmental conditions and latitudes.

plant biology↗

bioRxiv2023

CONSTANS alters the circadian clock in Arabidopsis thaliana

AbstractPlants are sessile organisms that have acquired highly plastic developmental strategies to adapt to the environment. Among these processes, the floral transition is essential to ensure reproductive success and is finely regulated by several internal and external genetic networks. The photoperiodic pathway, which controls the plant response to day length, is one of the most important pathways controlling flowering. In Arabidopsis photoperiodic flowering, CONSTANS (CO) is the central gene activating the expression of the florigen FLOWERING LOCUS T (FT) in the leaves at the end of a long day. CO expression is strongly regulated by the circadian clock. However, to date, no evidence has been reported regarding a feedback loop from the photoperiod pathway back to the circadian clock. Using transcriptional networks, we have identified relevant network motifs regulating the interplay between the circadian clock and the photoperiod pathway. Gene expression, chromatin immunoprecipitation experiments and phenotypic analysis allowed us to elucidate the role of CO over the circadian clock. Plants with altered CO expression showed a different internal clock period, measured by daily rhythmic movements in the leaves. We show that CO is able to activate key genes related to the circadian clock, such as CCA1, LHY, PRR5 and GI, at the end of a long day by binding to specific sites on their promoters. Moreover, a significant number of PRR5 repressed target genes are upregulated by CO, and this could explain the phase transition promoted by CO. The CO-PRR5 complex interacts with the bZIP transcription factor HY5 and helps to localize the complex in the promoters of clock genes. Our results indicate that there may be a feedback loop in which CO communicates back to the circadian clock, feeding seasonal information to the circadian system.

plant biology↗