Figure 1.

Structural features and expression patterns of the SlARF4 gene. A, Genomic structure of the SlARF4 gene. The pink portion represents the promoter region, the gray dots represent the introns, the gray boxes represent the exons, the yellow boxes represent the untranslated regions, the blue box represents the DNA-binding domain, the green box represents domain III, and the purple box represents domain IV. The putative cis-acting elements found in the promoter region are indicated by black bars. B, Expression pattern of SlARF4 monitored by qPCR. Expression in the root was taken as reference. C, Expression pattern of SlARF4 revealed by the expression of the GUS reporter gene driven by the SlARF4 promoter during fruit development and maturation. D, Auxin and ethylene regulation of SlARF4 expression. qPCR analysis of SlARF4 transcript levels in RNA samples extracted from 3-week-old light-grown seedlings treated with buffer (control), auxin (20 µm IAA for 2 h), or ethylene (50 µL L^–1 for 5 h). E, Auxin-responsiveness of SlARF4 promoter revealed by the expression of the GUS reporter gene driven by the SlARF4 promoter in seedlings treated with auxin (20 µm IAA for 2 h). UTR, Untranslated region; DBD, DNA-binding domain; 8DPA, fruit at 8 DPA; MG, fruit at mature green stage; Br, fruit at breaker; RR, red ripe fruit.