Ectopic overexpression of CpFT from ‘Manaohong’ cherry: Promoting floral induction and floral organ development in tobacco under rain shelter cultivation

The Flowering locus T (FT) is pivotal in integrating photoperiod signals to regulate plant floral transition and flowering. The FT protein is generally synthesized in leaves and translocated to the shoot apical meristem, where it interacts with FD to initiate flowering. Light intensity as a component of photoperiod signaling and a dynamically fluctuating factor in field light environments, however, the molecular mechanisms by which FT integrates changes in light intensity to regulate flowering in Chinese cherry remain unclear. Morphological analysis of flower buds and electron microscopic examination of pollen structures demonstrated that rain shelter (RS) extended the flowering period and enhanced the quantity and quality of flower buds. The expression levels of CpFT and CpFD genes were significantly up-regulated in various tissues under RS in the field. Based on these findings, it is hypothesized that FT exhibits a distinct response mechanism to changes in the light environment, thereby facilitating the regulation of floral induction under low-light conditions. Subsequently, plasmid recombination was carried out using seamless cloning technology, and tobacco was genetically transformed through leaf disc transformation. In addition, the ectopic overexpression of CpFT in tobacco promoted the expression of floral induction key genes, leading to the flowering time being advanced by 5-8 days, increased the number of flower buds and lateral buds, and staining rate increased by 58 % and the germination rate rose by 7 times. Furthermore, yeast two-hybrid and luciferase complementation assays confirmed the interaction between CpFT and CpFD. Combined with field observations of the 'Manaohong' cherry, these findings revealed that CpFT and CpFD constitute a signaling module in response to light intensity. This module positively regulates reproductive transitions and flowering time in cherries under low-light conditions, serving as a valuable reference for supplementing FT and FD to regulate floral induction in response to changes in the light environment.