The RING Finger Protein Nt RCP1 Is Involved in the Floral Transition in Tobacco（Nicotiana tabacum）

The transition from the vegetative phase to the reproductive phase is a major developmental process in flowering plants.The underlying mechanism controlling this cellular process remains a research focus in the field of plant molecular biology.In the present work,we identified a gene encoding the C3H2C3-type RING finger protein Nt RCP1 from tobacco BY-2 cells.Enzymatic analysis demonstrated that Nt RCP1 is a functional E3 ubiquitin ligase.In tobacco plants,expression level of Nt RCP1 was higher in the reproductive shoot apices than in the vegetative ones.Nt RCP1-overexpressing plants underwent a more rapid transition from the vegetative to the reproductive phase and flowered markedly earlier than the wild-type control.Histological analysis revealed that the shoot apical meristem of Nt RCP1-overexpressing plants initiated inflorescence primordia precociously compared to the wild-type plant due to accelerated cell division.Overexpression of Nt RCP1 in BY-2 suspension cells promoted cell division,which was a consequence of the shortened G2 phase in the cell cycle.Together,our data suggest that Nt RCP1 may act as a regulator of the phase transition,possibly through its role in cell cycle regulation,during vegetative/reproductive development in tobacco plant.