PsFUL acts as a bridge to regulate flowering in tree peony in autumn

Flowering is a major developmental process for angiosperms, and it mediates the transition from the vegetative to reproductive state. It is of great importance for ornamental plants since it determines their commercial traits and prices. Tree peony ( Paeonia suffruticosa Andr.) is highly esteemed for its ornamental value and cultural significance across various regions around the world. These perennial plants have been cultivated for centuries, primarily for their large, showy flowers and lush foliage. However, it blooms only once in the spring, which dramatically limits the development of the peony industry. Using forcing culture technique, we can make specific cultivars bloom in the autumn or winter. It regulates the flowering process through accelerating the flower differentiation and dormancy release. The mechanisms of flowering regulation including dormancy release in winter have been elucidated in details. However, the regulatory mechanisms of flowering in autumn remain largely unclear. Here, we utilized the system of flowering in the autumn and identified a Ps FRUITFUL transcription factor to modulate flowering through the direct activation of the expression of Flowering Locus T ( PsFT ). Furthermore, it can interact with Ps SUPPRESSOR OF OVEREXPRESSION OF CO 1 and Ps SHORT VEGETATIVE PHASE to antagonistically exert regulatory effects on the promotion or repression of flowering, respectively. This study elucidated the molecular mechanisms by which Ps FRUITFUL regulates flowering in tree peony, which will provide a perspective for further utilization of a molecular approach to breed new cultivars with distinct flowering time.