Fig. 4

MdARF19 directly binds to the promoter of MdFLP. (a) Y1H assays showed that MdARF19 can bind to the promoter fragments of MdFLP. (b) Effector constructs and the MdFLP promoter-driven reporter gene construct for transient expression assays. (c) GUS transient expression assays. Activation assay of MdFLP promoter activity in tobacco leaves by transient coexpression of MdARF19, as determined through a GUS activity assay. (d) GUS relative expression level in transgenic leaves by qRT-PCR analysis is shown. The endogenous gene RNR-2 of tobacco was used as an internal control for normalization. At least three independent samples were used for gene expression analyses. Error bars represent ± SE. Significant differences were determined by Student’s t-test (*P < 0.05). (e) Schematic diagram of the promoter in the MdFLP gene. The red circles indicate the AuxRE1 GAGACA motif. The black circle indicates the AuxRE2 GAGACA motif. The translational start site (ATG) is shown at position 0. (f) Y1H assays show that MdARF19 binds to AuxRE1 and AuxRE2 of structural MdFLP