Figure 3.

Ruby Is a Regulator of Anthocyanin Biosynthesis.

(A) and (B) Constitutive expression of Ruby cDNA under the control of the 35S promoter in tobacco results in strong anthocyanin-based pigmentation in undifferentiated callus (A) and regenerating shoots (B).

(C) Coexpression of the bHLH regulatory genes Delila and Mutabilis from snapdragon increases further anthocyanin accumulation in young leaves: (1) 35S:Ruby, (2) 35S:Ruby × 35S:Delila, (3) 35S:Ruby × 35S:Mutabilis, (4) 35S:Rosea1 × 35S:Delila, and (5) 35S:Rosea1 × 35S:Mutabilis.

(D) Ruby partners more successfully with the bHLH protein Mutabilis than with the bHLH protein Delila to activate anthocyanin biosynthesis in tobacco. Anthocyanin accumulation in two seedlings of each genotype is shown. 35S:Ruby^a and 35S:Ruby^c represent two independent transformants.

(E) Anthocyanin content in tobacco seedlings transformed with different regulatory genes (n = 9). Error bars show se of the mean.