Whole-tree dormancy dynamics in peach: Carbohydrate reservoirs and crosstalk with hormones and fatty acids

Dormancy is a crucial regulatory mechanism in perennial plants, safeguarding against cold winter stress and influencing subsequent reproductive success. While previous research has primarily focused on vegetative and floral buds during the dormancy-regrowth cycle-often overlooking the potential contributions of other plant compartments-this study adopts a 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 in relation to accumulated chilling units (CU) and growing degree hours (GDH). Our findings revealed that roots maintained the highest starch reserves during endodormancy, yet their soluble sugar accumulation appeared largely independent of local starch hydrolysis, suggesting translocation from aerial tissues (e.g., stems and branches). Starch catabolism in the aerial tissues likely provides soluble sugars to roots, which in turn sustain metabolic activity and contributes to dormancy release in buds. As dormancy advanced, soluble sugars were progressively redistributed, reaching peak levels in roots at the onset of ecodormancy and achieving a more uniform distribution across tissues during ecodormancy. A sharp surge in floral bud sugars towards budbreak, without a corresponding depletion of starch, suggests enhanced carbohydrate uptake capacity preceding budbreak. Transcriptomic analysis of roots revealed that genes positively correlated with starch content were enriched in fatty acid metabolism pathways, while those associated with soluble sugar accumulation were predominantly enriched in hormone signaling pathways and carbohydrate metabolism.