Mechanism of LED blue light regulation of glucosinolates biosynthesis and sulforaphane accumaltion in broccoli sprouts based on metabolomics and transcriptome

Broccoli sprouts, valued for their high nutritional content and richness in sulforaphane (SF), exhibit quality traits that are significantly modulated by light quality. However, the mechanisms underlying light regulation of glucosinolate (GSLs) biosynthesis in sprouts remain elusive. This study employed broccoli ‘Xianglv No. 3’ sprouts as experimental material, comparing sprouts grown in darkness (control) with those under five distinct LED light spectra. We assessed sprout growth, quantified GSLs and SF levels, measured total antioxidant capacity, and evaluated cytotoxicity against cancer cells. Integrated metabolomic and transcriptomic analyses were subsequently conducted. Results demonstrated that blue light significantly enhanced GSLs biosynthesis and SF accumulation in broccoli sprouts compared to the dark control, concurrently boosting antioxidant capacity and reducing cancer cell proliferation. Metabolomic profiling revealed significant alterations in 19 GSL metabolites under blue light, with 6 up-regulated and 13 down-regulated. Aliphatic GSLs exhibited the most pronounced changes, while SF increased markedly. Transcriptome analysis identified 9,128 differentially expressed genes (DEGs) in response to blue light. The results suggested that blue light regulated GSLs biosynthesis, particularly AGS, potentially by inhibiting carbon chain elongation and secondary modifications in their side chains. We propose a regulatory model of the HY5 - MYB28 - CYP83A1 signaling cascade. In this model, blue light induces the up-regulation of the light-responsive transcription factor HY5. HY5 subsequently activates the expression of its downstream target, MYB28 , which in turn upregulates CYP83A1 , ultimately driving enhanced GSL and SF production. This study elucidates the molecular basis for light quality regulation of broccoli sprout quality and provides valuable insights for advancing efficient cultivation and quality enhancement strategies.