SCL3 competes with DELLA and prevents its transactivation activity. (A) Interactions between IDDs and SCL3 in the Y2H assay. Schematic representations of the construct, BD-SCL3, and AD-IDDs are shown in the upper panel. (B) Y3H assay to determine the physical relationship between RGA, SCL3, and AtIDD3. The two lines on the right indicate yeasts on selection medium containing 5 and 10 mM 3-AT, respectively. (C) In vitro pull-down assays for determining the physical association of SCL3 and AtIDD3 and competition between RGA and SCL3 for AtIDD3. Flag-AtIDD3-C was used as bait. Numbers indicate the concentrations (in mM) of each protein in the reaction solution. (D) Transient reporter assay for identifying the effect of SCL3 on the transcriptional regulation of the DELLA/IDD complex. The −183 construct shown in Fig. 2C was used as the reporter. Results represent the means of three experiments; error bars indicate SD. The relative activity caused by vector control was set as 1. (E) A model for GA feedback regulation by the interaction among DELLA, SCL3, and IDD.