Flg22-dependent in-planta transcriptional activities mediated by SynEs. Flg22-responsiveness of two-week old Arabidopsis transgenic seedlings harboring the indicated SynE-4R (atg-GCAGGACATTTG-act), SynE-4R T (trimer of SynE-4R) and SynE-7R (atg-TGCTGACATAAA-act) expression constructs. Luciferin was added to the untreated (-Flg22) or treated (+Flg22) seedlings grown in micro-titer wells in liquid media and luciferase activity recorded using a CCD camera. The panels (A), (B) and (C) show two images for each SynE reporter construct: one dark field image and the other merged with the bright field image. (D) A transgenic line carrying the empty expression vector (K58 min) used as control. Images were taken at 4 hours after treatment with flg22.