Enhanced accumulation of anthocyanin in cultured strawberry cells by repetitive feeding of l-Phenylalanine into the medium

l-Phenylalanine (Phe), biosynthetic precursor of anthocyanin, was repetitively added into a suspension culture of strawberry cells, constantly producing anthocyanins. In the repetitive feeding culture, the maximum anthocyanin accumulation per culture was 30% and 81% higher than those in a single Phe-feeding culture and non-feeding culture, respectively. This means that the inhibitory effect of Phe on cell growth was successfully avoided and its intracellular free-state concentration was maintained at a higher level by the repetitive feeding of l-phenylalanine at relatively lower intra-medium concentration. These results support the phenylalanine pool hypothesis which states that the intracellular l-phenylalanine level determines anthocyanin production. However, it was also suggested that there exist other restrictions controlling intracellular anthocyanin accumulation.