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.