The uptake of acylated anthocyanin into isolated vacuoles from a cell suspension culture of Daucus carota.

Anthocyanin-containing vacuoles were isolated from protoplasts of a cell suspension culture of Daucus carota. The vacuoles were stable for at least 2 h as demonstrated by the fact that they showed no efflux of anthocyanin. The uptake of radioactively labelled anthocyanin was time-dependent with a pH optimum at 7.5, and could be inhibited by the protonophore carbonylcyanide m-chlorophenylhydrazone. Furthermore, the transport was specific, since vacuoles from other plant species showed no uptake of labelled anthocyanin, and strongly depended on acylation with sinapic acid, as deacylated glycosides were not taken up by isolated vacuoles. Hence, it is suggested that the acylation of anthocyanin, which is also required for the stabilization of colour in vacuoles, is important for transport, and that acylated anthocyanin is transported by a selective carrier and might be trapped by a pH-dependent conformational change of the molecule inside the acid vacuolar sap.