Regulation of anthocyanin biosynthesis in cell suspension cultures of Vitis in relation to cell division

Cell suspension cultures of Vitis produce anthocyanin in the dark after cessation of cell division. Production of anthocyanin was associated with increasing activities of phenylalanine ammonia‐lyase (PAL) and chalcone synthase (CHS) which followed transcript amounts. The level of endogenous phenylalanine, a precursor of anthocyanin, was also elevated before anthocyanin accumulated. Addition of phosphate to the medium at the early stationary phase induced cell division and completely inhibited the biosynthesis of anthocyanin. Activities of PAL and CHS did not increase in the stationary phase when phosphate was again added to the medium. The amount of phenylalanine decreased significantly after addition of phosphate. In contrast, when cells were inoculated into medium lacking phosphate, accumulation of anthocyanin was detected on day 2 and activities of PAL and CHS increased. The level of endogenous phenylalanine reached a maximum just before the initiation of anthocyanin synthesis. When phenylalanine was added to the medium in mid‐logarithmic phase when the phenylalanine pool was lowest, the level of phenylalanine was immediately elevated and accumulation of anthocyanin was initiated. Enzymatic activity of CHS also increased by the addition of phenylalanine. Transcript level increased synchronously with changes in the amount of phenylalanine, after its addition. We conclude that the induction of anthocyanin biosynthesis in cell suspension cultures of Vitis is triggered by high levels of endogenous phenylalanine following the cessation of cell division. Under these conditions, phenylalanine may be a signal that promotes transcription of genes of the anthocyanin biosynthetic pathway.