The present invention relates to nucleic acids and nucleic acid fragments encoding amino acid sequences for flavonoid biosynthetic enzymes in plants, and the use thereof for the modification of flavonoid biosynthesis in plants. More particularly, the flavonoid biosynthetic enzyme is selected from the group consisting of chalcone isomerase (CHI), chalcone synthase (CHS), chalcone reductase (CHR), dihydroflavonol 4-reductase (DFR), leucoanthocyanidin reductase (LCR), flavonoid 3′, 5′ hydrolase (F3′5′H), flavanone 3-hydroxylase (F3H), flavonoid 3′-hydroxylase (F3′H), phenylalanine ammonia-olyase (PAL) and vestitone reductase (VR), and functionally active fragments and variants thereof.