Induction of anthocyanin synthesis in relation to embryogenesis in a carrot suspension culture: Correlation of metabolic differentiation with morphological differentiation

Abstract

A system in which anthocyanin synthesis could be induced under a defined condition, was established in a carrot suspension culture. A cell suspension culture of carrot (Daucus carota L. cv. Kurodagosun) was subcultured for more than a year in a medium containing 5 × 10−7M 2,4‐dichlorophenoxyacetic acid (2,4‐D). At every subculture the cultures were sieved through nylon screens and the cells and cell clusters collected in the size range of 31–81 μm were transferred to a fresh medium. When the cells were transferred to a medium without auxin, synthesis of anthocyanin was induced. Zeatin promoted anthocyanin synthesis in a medium lacking auxin, with maximum yields of anthocyanin obtained at 10−7 to 10−8M zeatin, 2,4‐D at higher concentrations than 10−7M inhibited anthocyanin synthesis completely. The sieved cells were fractionated by Ficoll density gradient centrifugation. Somatic embryos were formed in the fraction of higher density (>14% of Ficoll) in a medium containing 10−7M zeatin but lacking auxin, while synthesis of anthocyanin was hardly observed. On the other hand, cells in the fraction of lower density (<12% of Ficoll) synthesized anthocyanin in the same medium, but formed few embryos. Forty to fifty percent of the total cells in this lighter cell fraction synthesized anthocyanin at a maximum. The similarity between anthocyanin synthesis and embryogenesis was observed in the time course as well as in the effects of growth regulators. The correlation between metabolic and morphological differentiation is discussed.