ASHS 2025 Conference

Dormancy constitutes a critical regulatory mechanism in perennial plants, conferring resilience to winter stress and impacting subsequent reproductive success. While previous investigations have predominantly focused on vegetative and floral buds during the dormancy-regrowth cycle, often neglecting the potential contributions of other plant compartments, this study adopts a comprehensive, whole-tree perspective. Utilizing four-year-old, root-bagged peach (Prunus persica) trees (cv. 'John Boy') we investigated dormancy progression by analyzing carbohydrate metabolism in different tissues relative to accumulated chilling units (CU) and growing degree hours (GDH). Our results demonstrated that roots maintained the highest starch reserves during endodormancy; however, soluble sugar accumulation in roots appeared largely independent of local starch hydrolysis, indicating potential translocation from distal storage tissues. This hypothesis is supported by the concomitant decline in starch content in branches and stems, which coincided with increased soluble sugar accumulation in these tissues. As dormancy progressed, soluble sugars were progressively redistributed, reaching peak concentrations in roots at the onset of ecodormancy and exhibiting a more uniform distribution across tissues during ecodormancy. A significant increase in floral bud soluble sugars preceding budbreak, without a corresponding starch depletion, suggests an enhanced capacity for carbohydrate uptake. Transcriptomic analysis of root tissues across all dormancy stages identified two key gene modules (ME) exhibiting inverse correlations with carbohydrate levels. Genes within ME3, associated with starch accumulation, were significantly enriched in fatty acid metabolism pathways—including SBE2, DBE1, FAD8 and KAS1. Notably, the upregulation of FAD8 during ecodormancy suggests increased membrane fluidity, potentially facilitating carbohydrate transport. Conversely, ME10 genes, associated with soluble sugar levels, displayed enrichment in hormone signaling and carbohydrate metabolism pathways—including SUS3, BAM6, and GH9A1. These findings underscore the coordinated regulation of carbohydrate metabolism and membrane lipid composition during dormancy transitions and bud break. Furthermore, the data indicate that starch catabolism in branches and stems during chilling accumulation serves as a source of soluble sugars for roots, which in turn may sustain metabolic activity and contribute to dormancy release in buds. Future research employing this whole-tree system is warranted to elucidate the comprehensive roles of roots and other storage organs in the regulation of dormancy.