The Role of Endogenous Hormones in Regulating Early Development of Stone Fruit

Stone fruits, mainly represented by <i>Prunus</i> species, are economically important crops whose yield potential and final quality are largely determined during early fruit development. This early phase, encompassing pollination, fertilization, fruit set, cell division, and pit hardening, involves irreversible developmental decisions that govern fruit survival, size, and productivity. In this review, recent advances in endogenous hormonal regulation during early stone fruit development are synthesized, with emphasis on auxin, gibberellin (GA), cytokinin (CTK), and abscisic acid (ABA). Auxin and GA act as core growth-promoting signals that synergistically initiate fruit set, stimulate cell division and expansion, and support parthenocarpy development, while CTK reinforces early cell proliferation and contributes to final fruit size. In contrast, ABA primarily functions as a growth-inhibitory regulator, integrating developmental and environmental cues to promote fruit growth arrest and abscission under unfavorable conditions. These hormones interact through dynamic synergistic and antagonistic networks that are continuously reprogrammed across developmental stages and tissues. This review provides a regulatory framework for understanding hormone-mediated early fruit development in stone fruits and offers guidance for orchard management and future molecular breeding to stabilize fruit set and improve yield and quality.