ERF-mediated transcription from native and synthetic promoters. Transient expression in single cell system has been used to assess the transcriptional activity of ERF proteins from different subclasses. The fluorescence of the reporter gene was measured by flow cytometry upon co-transfection with a reporter construct (GCC:: GFP or Sl-Osmotin Promoter:: GFP or Sl-E4promoter:: GFP) and an effector construct (35S::Sl-ERF or 35S::Sl-ERF-SRDX). The basal fluorescence obtained in the assay transfected with the reporter construct and an empty effector construct was taken as reference (100 % relative fluorescence). (A) ERF activity on synthetic promoter containing 4 direct repeats of the GCC-box. (B) ERF activity on osmotin native promoter containing the canonical GCC motif. (C) ERF activity on E4 native promoter lacking the GCC motif. The results are mean of 3 independent biological replicates. Analysis of variance (ANOVA) was performed to determine the effect of the subclass on ERF activity (p<0.05). The Mann–Whitney test indicates significant result (p<0.05). Black and gray Bars indicate relative fluorescence obtained with native or repression version of each ERF, respectively. Bars indicate SE of the mean.