Molecular regulation of anthocyanin biosynthesis in soybean

Anthocyanins are specialized flavonoid pigments that contribute to pigmentation in soybean (Glycine max) seed coats, hypocotyls, stems, and flowers, as well as to photoprotection, stress adaptation, and nutritional quality. Although the core anthocyanin biosynthetic pathway is broadly conserved in plants, recent advances highlight anthocyanin accumulation in soybean as a systems-level output of flavonoid metabolic partitioning, tissue-specific transcriptional regulation, and environmental responsiveness. Here, we summarize recent progress in soybean anthocyanin biosynthesis and regulation, with emphasis on metabolic partitioning, tissue-specific regulatory modules, light-responsive pathways, and the functional diversification of anthocyanin-related MYB regulators. We further discuss unresolved questions related to pigment stabilization, stress-associated functions, multilayer regulatory networks, and precision manipulation of anthocyanin-related traits. These perspectives provide a framework for molecular breeding, regulatory engineering, and metabolic pathway optimization aimed at improving soybean quality, nutritional value, and stress resilience.