Strawberry cryptochrome FvCRY1 and FvCRY2 transcriptionally regulate anthocyanin biosynthesis and sugar metabolism

Anthocyanin pigmentation and soluble sugar content are important factors affecting the quality of strawberry fruits, and their accumulation processes are profoundly influenced by light signals. However, the molecular mechanism through which light regulates this process remains to be fully elucidated. Here, we identified two blue light receptors, FvCRY1 and FvCRY2, from woodland strawberry. Functional complementation in Arabidopsis cryptochrome mutant confirmed their photoperceptor roles. Stable overexpression of FvCRYs in cultivated strawberry (Fragaria × ananassa 'Ningyu') significantly enhanced anthocyanin accumulation and soluble sugar content, concomitant with upregulation of key biosynthetic genes. Strikingly, yeast one-hybrid and dual-luciferase assays revealed FvCRYs possess intrinsic transcriptional activation domains that directly bind E-box cis-elements in promoters of anthocyanin synthesis gene FvCHS2, FvDFR2, FvCHI, and sugar metabolism-related genes FvSFP9 and FvINV. This DNA-binding capacity is potentiated by blue light, enabling transcriptional expression of anthocyanin synthesis and sugar metabolism genes. Our findings unveil a non-canonical cryptochrome signaling mechanism involving direct receptor-promoter interaction, redefining our understanding of photoreceptor-mediated frui quality regulation.