Figure 1.

Transcriptional activity of the auxin-inducible DR5 synthetic promoter in response to 2,4-dichlorophenoxyacetic acid and auxin inhibitor treatments. The endogenous concentration of auxin was revealed in soybean transgenic roots expressing the DR5::GUS reporter (A). The DR5-REV::GUS transgenic roots did not show any β-glucuronidase activity (B). Upon auxin treatment, the DR5 promoter was ubiquitously active in the soybean transgenic roots (C). While individual treatment of the plants with L-kynurenine, an inhibitor of auxin biosynthesis (D), and TIBA, an inhibitor of auxin transport (E), did not significantly affect the activity of the DR5 synthetic promoter, a combined treatment of the two drugs was sufficient to reduce DR5::GUS activity in the entire soybean root system (F). Scale = 200 µm.