Anthocyanin Biosynthesis, Multilayered Regulation, and Biotechnological Applications in Fruits

Anthocyanins are water-soluble flavonoid pigments that confer vivid coloration to fruits and provide multiple health benefits. Here, we critically review recent advances in the structural diversity, biosynthetic pathways, and multilayered regulation of fruit anthocyanins. We summarize the enzymatic and postsynthetic modifications that determine pigment stability, and examine the MYB-bHLH-WD40 (MBW) complex, its interplay with NAC, WRKY, ERF, and bZIP factors, and the roles of epigenetic and post-translational controls. Hormonal, environmental, and nutrient signals are integrated into a unified model, emphasizing the contrasting regulatory logics of climacteric versus nonclimacteric fruits and the tissue specificity of peel- vs flesh-localized pigmentation. We evaluate biotechnological strategies, including CRISPR-based precision breeding, microbial cell factories, and plant metabolic engineering, highlighting both transformative potential and translational bottlenecks. Finally, we propose future directions for translating fundamental knowledge into anthocyanin-enriched fruits and sustainable production systems for the food and health industries.