BnaA03.WRKY28 promotes axillary branch formation. A, Phenotype of branching (indicated by arrows) in BnaA03.WRKY28 OE lines (left) and WT (right). Scale bar, 10 cm. B and C, Close-up view of the representative leaf axil in the square in (A); scale bars, 2 cm. D and E, Statistical description of lateral branches or buds in every order branching (D) and branching positions that produce two or more branches in one axil (E) in BnaA03.WRKY28 OE lines and late-growth WT plants (n = 3) for two years (2019 and 2020). F, Schematic of branches in WRKY28-OE lines and WT plants. Arrows, branches; ellipses, cauline leaves. G, GUS staining showing the expression of BnaA03.WRKY28. Left, two-week-old plants; scale bar, 2 cm. Middle, six-week-old plants; scale bar, 2 cm. Right, close-up view of the leaf axils in the square in the middle image; scale bar, 1 cm. H, RT-qPCR to examine transcription levels of branching-related genes in BnaA03.WRKY28 OE lines and in the WT. Data are shown as means ± sd (n = 3). Asterisks indicate significant differences (t test; *P < 0.05, **P < 0.01). I, EMSA to detect BnaA03.WRKY28 binding to the BnaC03.BRC1 promoter. The sequence containing two W-box motifs in the BnaC03.BRC1 promoter was used as a DNA probe.