Chilling Accumulation Shapes Transcriptomic Responses to Warming Exposure During Grapevine Deacclimation.

During winter, grapevine (Vitis vinifera) bud dormancy and cold hardiness are regulated by complex interactions between chilling accumulation and warm temperature cues. However, the molecular mechanisms underlying physiological transitions during winter remain poorly understood. In this study, we performed time-series RNA-seq on "Cabernet Sauvignon" dormant buds with varying chilling accumulation, followed by warm temperature exposure under a controlled forcing condition. Using weighted gene co-expression network analysis, empirical modeling, and a novel calculation of molecular warm temperature response rate, we identified gene expression patterns responsive to warm temperature exposure alone, chilling alone, and their interaction. Genes responsive to warm temperature exposure under forcing conditions showed rapid, chilling-independent activation and were primarily associated with metabolism, environmental sensing, and auxin signaling. Chilling-responsive genes were enriched for functions of chromatin remodeling and heat shock protein pathways, which may indicate progressive cellular reprogramming under field conditions. Interaction-responsive genes, including those involved in ABA/auxin metabolism and cell wall modification, may function in both dormancy progression and deacclimation. These findings provide a transcriptomic framework suggesting how chilling and temperature synergistically regulate dormancy transitions in grapevine, thereby enhancing the understanding of temperature sensing and response and the chilling-mediated dormancy progression underlying grapevine dormant season physiology.