Xylem sap flow is critical for grapevine dormancy release and early spring growth. However, the dynamic metabolic shifts within the sap during this transition are not fully understood. In this study, we employed untargeted liquid chromatography-mass spectrometry (LC-MS) to profile the xylem sap metabolome of grapevine across key developmental stages in early spring. We detected 585 and 407 metabolites in positive and negative ion modes, respectively. Our time-resolved analysis revealed a highly orchestrated, three-phase metabolic reprogramming to prepare the vine for budburst. The initial stage was marked by the activation of amino acid metabolism, exemplified by a significant increase in glutamic acid, indicating the mobilization of foundational nitrogenous resources. This was followed by a broad upregulation of biosynthetic pathways for secondary metabolites and phenylpropanoids, likely priming the plant for defense and structural development. The final stage was characterized by a decisive shift towards purine metabolism, essential for producing energy (ATP) and nucleic acids to fuel imminent cell division. Concurrently, a strategic reallocation of resources was observed, with a dramatic decrease in dormancy-associated defense compounds like resveratrol. Collectively, these findings provide the first detailed metabolic map of this transition, revealing a coordinated biochemical strategy for dormancy release and identifying potential biomarkers for assessing vine readiness for spring growth.
Xie et al. (Thu,) studied this question.