FIGURE 5.

GI binds to ORE1 promoter and activates its expression. (A) Diurnal expression of ORE1 under long-day (LD; 16 h light/8 h dark) and short-day (SD; 8 h light/16 h dark) photoperiod. (B) Abundance of ORE1 mRNA in wild-type and gi-2 mutant leaves under continuous light (LL). White bars indicate subjective day, and gray shading indicates subjective night. (C) ORE1 promoter-binding affinity of GI in CsV:GI-GFP transgenic plants. Schematic representation of amplicons 1–9 of the ORE1 promoter amplified in the chromatin immunoprecipitation-quantitative PCR (ChIP-qPCR) assay are indicated. Amplicon 9 was used as an internal control. Leaves were harvested at 12 h after light on. Fold enrichment indicates the ratio of chromatin immunoprecipitated using anti-GFP antibody to that immunoprecipitated using anti-IgG antibody. Asterisks indicate statistically significant difference compared with the IgG control. (D) ORE1 promoter-binding activity of GI in the elf4 mutant relative to that in the wild type at amplicons 1, 2, and 3. Three biological replicates were performed. Asterisks indicate significant differences (*p < 0.05, **p < 0.01, ***p < 0.005; Student’s t-test).