MdSPL14 and MdWRKY24 directly repress the expression of MdCKX5. A)MdCKX5 promoter sequence analysis reveals the presence of GTAC and W-box-binding elements. B) Y1H assay indicating that MdSPL14 and MdWRKY24 can bind to the MdCKX5 promoter in yeast cells. C) Schematic diagram of the constructed reporter and effector vectors. D, E) LUC assay indicating that MdSPL14 and MdWRKY24 inhibit the MdCKX5 promoter activity in N. benthamiana, respectively. Data are means ± Sd (n = 3). Values with different letters are significantly different according to 1-way ANOVA followed by Tukey's test (P < 0.05). F) EMSA confirming that MdSPL14 and MdWRKY24 bind to the MdCKX5 promoter in vitro, respectively. The probe was a biotin-labeled fragment of the MdCKX5 promoter, whereas the competitor probe was an unlabeled probe (10-, 50-, and 50-fold molar excess). The “+” represents the presence of relevant probes or proteins, and “-” represents the absence of relevant probes or proteins. “Mut” represents mutant probes with core sequences.