Structure and function of Vitis vinifera Arabidopsis Response Regulator 1 (VvARR1) protein provide insights into the regulatory mechanism of grape fruit shape through gibberellin-cytokinin crosstalk.

Grape fruit shape is a crucial agricultural trait that significantly impacts the commercial value of grapes. In this study, we developed a machine learning system to classify grape fruit shapes, offering an objective phenotypic assessment method. Multi-omics profiling indicated that exogenous GA treatment-induced fruit shape variations may occur via gibberellin-cytokinin crosstalk and identified VvARR1 as a key gene. VvARR1 contains a 2043-bp ORF encoding a 680-amino-acid protein with a molecular weight of 74.1 kDa. Transgenic tomato experiments verified the function of VvARR1, and its expression profiles vary among different fruit shape varieties. Molecular docking and dynamics revealed hydrogen bond interactions between VvARR1 and specific DNA sequences containing the GAT motif. These findings provide a molecular framework for elucidating how VvARR1 modulates cytokinin-responsive pathways to shape fruit, enhancing our understanding of plant hormone interactions and strategies for crop enhancement.