TCP4 directly binds to the EXB1 promoter to negatively regulate EXB1 expression to finely modulate the morphology of styles. A) Relative expression levels of EXB1 in the wild type, crc, tcpDUO, and tcpDUO crc apical gynoecium were detected by RT-qPCR. Actin2 was used as the internal reference. The reported results are the mean (±Sd) of three biological replicates. One-way ANOVA was performed with LSD/Duncan pairwise comparison testing. Different lowercase letters indicate significant differences (P < 0.05). B) ChIP-seq data showed that TCP4 protein was enriched in the promoter region of EXB1 in vivo. C) EMSA analysis indicated that TCP4 protein was directly bound to the promoter of EXB1 in vitro. D) Gynoecium from wild type and heterozygous exb1-D. Bars = 10 μm. E) Siliques from the apical gynoecium of wild type and heterozygous exb1-D. Bars = 1 mm. F) Gynoecium from wild type, pEXB1–EXB1–SRDX-7, and pEXB1–EXB1–SRDX-26. Bars = 10 μm. G) Siliques from the apical gynoecium of wild type, pEXB1–EXB1–SRDX-7, and pEXB1–EXB1–SRDX-26. Bars = 1 mm. H) Statistical analysis of the style lengths of wild type, heterozygous exb1-D, pEXB1–EXB1–SRDX-7, and pEXB1–EXB1–SRDX-26 apical gynoecium at flower development stage 11. The closed circles represent quartiles, and the short black lines represents the medians in the violin plot. Statistical significance was determined by one-way ANOVA (n ≥ 18). Significant differences at P < 0.05 are indicated by different lowercase letters (Supplementary Data Set 8). I) Statistical analysis of the style lengths of wild type, heterozygous exb1-D, pEXB1–EXB1–SRDX-7, and pEXB1–EXB1–SRDX-26 siliques. The closed circles represent quartiles, and the short black lines represents the medians in the violin plot. Statistical significance was determined by one-way ANOVA (n = 15). Significant differences at P < 0.05 are indicated by different lowercase letters (Supplementary Data Set 8).