Light-induced morphological alteration in anthocyanin-accumulating vacuoles of maize cells

To determine whether the light control of the maize anthocyanin pathway is mediated by the expression of the B/R and C1/PL regulators and/or the biosynthetic genes [ 23], we investigated the pigmentation of BMS cells expressing the R and C1 genes from the constitutive CaMV 35S promoter (BMS35S::R+35S::C1) [27]. BMS35S::R+35S::C1 cells grown in complete darkness for 30 days were fully pigmented with anthocyanins ( Fig. 1A). The bombardment of BMS cells with the R and C1 regulators driven from the 35S promoter (p35SR + p35SC1) resulted in the accumulation of red cells within 15 hours, even when cells were kept in complete darkness after bombardment ( compare Fig. 1B and 1C). These results indicate that the constitutive expression of the R and C1 regulators is sufficient for the activation of the pathway, even in the absence of light.