Physiological, hormonal, and transcriptomic analyses identify VvASMT as a candidate regulator associated with GA3-induced ovule abortion in grapevine

Gibberellic acid (GA 3 ) is widely used to induce seedlessness in table grapes, yet the molecular basis linking exogenous GA signaling to ovule abortion remains poorly understood. In this study, we investigated the physiological, transcriptomic, and functional responses of ‘Shine Muscat’ ovules to GA 3 treatment. GA 3 markedly reduced pollen viability, impaired pollen tube elongation, and increased the seedless berry rate to 89.61%. Histological observations showed that ovule abortion was initiated after fertilization, with degeneration of the embryo sac and endosperm from 9 d after flowering. Hormone profiling revealed dynamics changes in GA, IAA, and ABA level, whereas metabolite analysis showed a rapid increase in putrescine accumulation in response to GA 3 . Transcriptome analysis of early-stage ovules uncovered extensive reprogramming of hormone signaling, polyamine metabolism, ROS-related processes, and programmed cell death pathways. Among the GA 3 - responsive genes, VvASMT , which encodes an acetylserotonin O-methyltransferase associated with melatonin biosynthesis, was strongly induced during the early response phase. Heterologous overexpression of VvASMT in tomato caused a severe reduction in seed number, supporting a conserved role in repressing seed development. A candidate gene correlation network further highlighted VvASMT as a highly connected node linking polyamine/melatonin-associated metabolism with hormone signaling. Collectively, these findings indicate that GA 3 -induced seedlessness is associated with coordinated changes in hormone homeostasis, putrescine metabolism, ROS/PCD-related regulation, and identifies VvASMT as a candidate regulator associated with ovule abortion, which provides new insight into the regulatory basis of GA3-induced seedlessness in grapevine.