Genome-wide identified VvOFP genes family and VvOFP4 functional characterization provide insight into fruit shape in grape

Ovate Family Proteins (OFPs) are emerging as novel transcriptional regulators of fruit shape. Despite their established role in various species, their involvement in regulating grape fruit shape remains understudied. This study encompassed a comprehensive evaluation of 16 grape OFP genes in total at the whole genome level. Phylogenetic and synteny analyses established a close relationship between grape VvOFP genes and their tomato counterparts. Expression profiling post-treatment with gibberellic acid (GA3) and thidiazuron (TDZ) revealed that certain OFP genes responded to these regulators, with VvOFP4 showing peak expression three days post-anthesis. Functional assays via overexpression of VvOFP4 in tobacco and tomato altered the morphology of both vegetative and reproductive organs, including leaves, stamens, and fruits/pods. Paraffin sections of transgenic tobacco stems and tomato fruits demonstrated that VvOFP4 overexpression modifies cell dimensions, leading to changes in organ morphology. Additionally, treatments with GA3 and TDZ similarly influenced the shape of grape pulp cells and thereby the overall fruit morphology. These findings suggest that the VvOFP4 gene plays a crucial role in fruit shape determination by modulating cell shape and presents a potential target for future grape breeding programs aimed at diversifying fruit shapes.