Curing strategy reshapes saccharide dynamics and drives quality formation in tobacco: Insights from time series-targeted glycomics and widely-targeted metabolomics

Carbohydrate metabolism during flue-curing is central to tobacco quality. To elucidate the saccharide dynamics underlying tobacco quality, a comprehensive analysis was conducted using time series-targeted glycomics and widely targeted metabolomics under accelerated energy-saving (AE), balanced energy-utilization (BE), and colossal energy-consumption (CE). Phenotypic, pigment and carbohydrate analyses confirmed that while all treatments achieved complete degreening by 42 °C, the initial yellowing kinetics varied significantly, which induced marked divergence in final carbohydrate composition. Targeted glycomics and network analysis revealed dynamic, temperature-dependent shifts in saccharide metabolism, identifying stage-specific biomarkers (e.g., Glucuronic acid) and hub biomarkers (sucrose and Mannose). Widely targeted metabolomics further demonstrated that the treatments caused extensive reprogramming of secondary metabolism. Multi-omics integration identified key saccharides as network hubs, with galactose, arabinose, and glucose showing predominant negative correlations, and rhamnose, glucuronic acid, and fucose showing bidirectional patterns (both positive and negative), which linked to flavor-related metabolites. Specifically, AE (shortest yellowing period) led to higher residual starch and elevated simple sugars, but impaired sugar transformation, diminishing flavor-related secondary metabolites (flavonoids and terpenoids), thereby reducing sensory quality. BE yielded the most balanced sensory profile, with enhanced sweet aroma and quality by improving the accumulation of flavor-related compounds. In contrast, CE promoted flavonoids and terpenoids accumulation but introduced burnt off-flavors. These findings elucidated that curing strategies could be selectively optimized to steer metabolic pathways toward desired quality outcomes, establishing a scientific basis for producing tailored, high-quality tobacco with improved energy efficiency.