Multi-Omics Analysis Reveals Crucial Mechanisms by Which Shading Intensity Regulates Sugar Metabolism in Asparagus Stems

Shade stress is a crucial constraint on asparagus growth in intercropping and dense-planting systems. However, the physiological and molecular mechanisms linking shading intensity to sugar metabolism remain insufficiently understood. Herein, integrating newly generated physiological data with a targeted re-analysis of previously published omics datasets, we elucidated sugar metabolism responses in asparagus stems under different shading intensities (0%, 35%, 55%, and 75%). Moderate shading (55%) was associated with higher sucrose and fructose contents, together with increased activities of key sucrose metabolism enzymes, including sucrose synthase (SUS), soluble acid invertase (S-AI), and sucrose phosphate synthase (SPS), accompanied by differential changes in antioxidant enzyme activities (SOD, CAT and POD). Metabolomic analysis revealed a shift in carbon allocation under 55% shading, characterized by the accumulation of nucleotide sugars such as UDP-galactose and GDP-L-fucose. Transcriptomic analysis further indicated the enrichment of glycolysis/gluconeogenesis pathways under this shading condition, along with the upregulation of pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH) genes. Collectively, rather than merely confirming known shading responses, these findings provide new empirical evidence that asparagus stems actively reprogram their energy homeostasis and invoke alternative carbon partitioning pathways specifically at a 55% shading threshold.