FvbHLH78 interacts with FvCRY2 to promote flowering in woodland strawberry

Abstract

Flowering is a crucial agricultural trait of strawberries. While the bHLH family comprises numerous members in plants, its function in controlling strawberry flowering remains largely unexplored. In this study, FvbHLH78 was found to be highly expressed in the shoot apices and ripening fruits of woodland strawberry (Fragaria vesca). FvbHLH78 is localized to the nucleus and exhibits self-activating transcriptional properties. Overexpression of FvbHLH78 in woodland strawberry resulted in an early flowering phenotype compared to the control plants. This phenomenon was attributed to FvbHLH78 directly binding to the promoters of the genes associated with flowering, namely FvFT, FvSEP3, FvLFY, and FvAGL42. Moreover, FvbHLH78 interacted with a blue light receptor FvCRY2, which enhances FvbHLH78 promoter-binding affinity to FvFT, FvSEP3, FvLFY, and FvAGL42, thereby accelerating flowering. Collectively, these findings demonstrate that the FvbHLH78-FvCRY2 complex in strawberries acts as an enhancer of genes associated with flowering, thereby accelerating the flowering process. These data offer an understanding for enriching the roles of bHLH78 and accelerating flowering in strawberry.