Flavonoids are secondary metabolites found in plants, with diverse biological functions including protection against UV-B radiation, pathogen infection, and roles in nodulation and pollen fertility. The biosynthesis of flavonoids occurs through the phenylpropanoid pathway, involving enzymes such as chalcone synthase, which produces chalcone scaffolds. The pathway is regulated by transcription factors like MYB, bHLH, and WD40 proteins, enabling metabolic engineering for valuable applications. Flavonoids are modified by enzymes that alter their structure, leading to different subclasses. The biosynthesis pathway is organized into macromolecular complexes, enhancing the efficiency of natural product synthesis. Flavonoids are synthesized in the cytoplasm and transported to vacuoles or cell walls, where they accumulate. The regulation of flavonoid biosynthesis involves complex interactions between transcription factors, with different species showing variations in regulation. Flavonoids play roles in plant defense against pathogens and herbivores, UV-B protection, and signaling during reproduction. In legumes, flavonoids are involved in nodulation and pollen fertility. Genetic engineering of flavonoid biosynthesis has been used to produce valuable compounds, and combinatorial biosynthesis in microorganisms has enabled the production of plant-specific metabolites. The future challenges include understanding the regulation of flavonoid pathways, protein-protein interactions, and the transport of flavonoids into vacuoles. Advances in genetic engineering and microbial systems are expected to enhance the production of flavonoids and related compounds for industrial and agricultural applications.Flavonoids are secondary metabolites found in plants, with diverse biological functions including protection against UV-B radiation, pathogen infection, and roles in nodulation and pollen fertility. The biosynthesis of flavonoids occurs through the phenylpropanoid pathway, involving enzymes such as chalcone synthase, which produces chalcone scaffolds. The pathway is regulated by transcription factors like MYB, bHLH, and WD40 proteins, enabling metabolic engineering for valuable applications. Flavonoids are modified by enzymes that alter their structure, leading to different subclasses. The biosynthesis pathway is organized into macromolecular complexes, enhancing the efficiency of natural product synthesis. Flavonoids are synthesized in the cytoplasm and transported to vacuoles or cell walls, where they accumulate. The regulation of flavonoid biosynthesis involves complex interactions between transcription factors, with different species showing variations in regulation. Flavonoids play roles in plant defense against pathogens and herbivores, UV-B protection, and signaling during reproduction. In legumes, flavonoids are involved in nodulation and pollen fertility. Genetic engineering of flavonoid biosynthesis has been used to produce valuable compounds, and combinatorial biosynthesis in microorganisms has enabled the production of plant-specific metabolites. The future challenges include understanding the regulation of flavonoid pathways, protein-protein interactions, and the transport of flavonoids into vacuoles. Advances in genetic engineering and microbial systems are expected to enhance the production of flavonoids and related compounds for industrial and agricultural applications.