Figure 6.

Design and function of the synthetic eukaryotic signal transduction system. (A) Diagram of PlantPho promoter, showing four Pho boxes fused to a minimal plant promoter, the −46 region of the CaMV35S promoter, with the nucleotide sequence of one Pho box indicated below. (B) Average GUS activity (nmoles 4-MU mg⁻¹ protein h⁻¹) in transgenic plants, containing the PlantPho system as a function of cytokinin (t-zeatin) concentration. Error bars indicate±one standard error. (C) Linear increase in GUS activity (nmoles 4-MU mg⁻¹ protein h⁻¹) with t-zeatin concentration. 4-MU, 4-methylumbelliferone.