Unraveling the complexity of rootstock-scion interactions: A critical synthesis of physiological mechanisms, stress resilience, and biotechnological innovations

Grafting elite scions onto specialized rootstocks constitutes a cornerstone of modern horticulture, functioning as a critical dynamic interface between the plant and the edaphic environment. While the empirical use of rootstocks dates back centuries, contemporary agriculture requires a paradigm shift from observational practices to mechanistic precision. This critical review synthesizes current multidisciplinary knowledge on rootstock-scion interactions across major woody perennials, including Vitis, Malus, Pyrus, Prunus , and Citrus spp. We systematically analyze the physiological, biochemical, and molecular networks governing scion modification, challenging traditional unidirectional models. Key focal points include the hormonal orchestration of vigor—mediated by auxin–cytokinin–ABA crosstalk—and the hydraulic architecture dictating whole-plant water transport. Furthermore, we critically evaluate the genetic underpinnings of dwarfing, highlighting major quantitative trait loci alongside the emerging role of long-distance macromolecular trafficking and epigenetic reprogramming in systemic signaling. The impact of rootstock selection on mitigating abiotic constraints and biotic threats is dissected, identifying critical discrepancies between controlled-environment findings and field-scale realities. Emerging and still underexplored frontiers, including the rootstock microbiome, polyploidy (whose effects on root exudates and microbiome recruitment remain poorly resolved), and graft-delivered biotechnologies such as trans-grafting and genome editing, are evaluated for their translational potential. By integrating these findings, explicitly outlining prevailing knowledge gaps, and proposing five priority research directions, this review provides a rigorous theoretical framework to accelerate rootstock breeding programs tailored for resilient, high-density orchard systems in the face of global climate change.