Expression mediated by selected SynEs upon Pep25 treatment of parsley protoplasts. (A) LUC activity was measured as counts per second (cps) of photon emission and Pep25-dependent fold induction values for the individual indicated SynEs, were calculated by dividing the counts per second (cps) values of the samples derived from stimulated protoplasts (induced state) with the corresponding cps values of the samples from untreated protoplasts for each time point. A subset of SynEs show inducibility upon Pep25 stimulation (ratio >1), whereas a subset of SynEs show Pep25-dependent decrease in activity (ratio <1) (see Additional file 7 for details). (B-D) LUC activities of three selected SynEs and their derivatives 4 hours after transfection into parsley protoplasts in the presence (induced) or absence (control) of Pep25 as indicated. SynE-2- (B, tcc-GACCTAGGTTGA-gaa(x)14atg-GCACAAGTTTGG-act), SynE-4- (C, tcc-ATTGAGACATAC-gaa(x)14atg-GCAGGACATTTG-act), and SynE-11- (D, tcc-ACCTGGGTGAAT-gaa(x)14atg-CTCTGTGCCTAG-act) mediated expressions were compared with those of derivatives containing only the 12 N-left (SynEs-L) or the 12 N-right(SynEs-R) sequence of the corresponding original SynEs, respectively. Note that SynE-2R, SynE-4R and SynE-11R supported enhanced transcriptional activity upon Pep25 stimulation. The transcriptional activity was measured as counts per second (cps) of photon emission produced by the LUC activity. The empty expression vector K58 min served as a control for background activity. A minimum of three biological replicates were performed for each SynE (error bars indicate SE).