Grafting-associated chilling tolerance in grapevine involves VvERF113-regulated stilbene biosynthesis and changes in chromatin accessibility

Grapevine (Vitis vinifera L.) is highly sensitive to low temperature, yet the molecular basis by which rootstocks improve scion chilling tolerance remains poorly understood. Here, we show that the cold-tolerant rootstock CR3 markedly enhances chilling tolerance in the grape cultivar ‘Miguang’. Integrated ATAC-seq and RNA-seq analyses revealed that grafted plants underwent broader chilling-induced changes in chromatin accessibility than self-rooted plants, particularly in genomic regions associated with stress responses and secondary metabolism. Among these pathways, stilbene biosynthesis was strongly activated in grafted plants, accompanied by increased expression of VvSTS genes and higher accumulation of stilbene compounds. Exogenous resveratrol treatment further alleviated chilling-induced damage, supporting a protective role for stilbenes in grapevine chilling adaptation. We further identified the ethylene-responsive transcription factor VvERF113 as a direct repressor of VvSTS expression. Overexpression of VvERF113 suppressed stilbene accumulation and reduced chilling tolerance, whereas RNA interference of VvERF113 promoted stilbene biosynthesis and enhanced chilling tolerance. Together, these findings indicate that repression of VvERF113 in grafted plants may contribute to the enhanced activation of the stilbene pathway associated with CR3 grafting, thereby improving grapevine chilling tolerance, and provide a mechanistic framework for enhancing cold resistance through scion-rootstock interactions.