Figure 3.

WRKY7 is a transcriptional repressor in plant cells. A, Constructs of reporter and effector genes. The GUS reporter gene is driven by a synthetic promoter consisting of the −100 minimal CaMV 35S promoter and eight copies of the LexA operator sequence. The effector genes were clone into pTA7002 behind the steroid-inducible promoter. The three effector genes encode LexADBA-WRKY7 fusion protein (LexA-W7), LexA DBD (LexA), and WRKY7 (W7), respectively. B, Effects on the GUS reporter gene expression by induced expression of effector genes. The ratios of GUS activities were calculated from the GUS activities in the leaves harvested prior to DEX treatment (−) over those determined in the leaves harvested 18 h after DEX treatment (+). Only those transformants that displayed induced expression of the effector genes as determined from RNA blotting following DEX treatment were used in the analyses. The GUS activities in the transformants harboring the LexA-W7 effector decreased by approximately 4- to 5-fold following induced expression of the fusion effector, whereas the GUS activities in the transformants harboring the LexA or WRKY7 effector remained largely unchanged following induction of the effector gene expression. The means and errors were calculated from at least 15 positive transformants, and the experiments were repeated; two repetitions gave very similar results.