A schematic presentation of the bidirectional promoter (P85–P87), promoter-reporter constructs and transient expression analysis using two reporter genes (GFP and GUS) in both orientations.

<p>(A) A schematic map of the bidirectional promoter (P85–P87) located in the intergenic region (IR, 1285 bp, genomic coordinates 17,033,863–17,035,120; TAIR 10) in Arabidopsis chromosome 4, directs two divergent <i>At4g35985</i> and <i>At4g35987</i> genes arranged in head-to-head orientation. (B–C) Schematic diagram of bidirectional promoter-reporter gene constructs: GFP::P85–P87::GUS and GFP::P87–P85::GUS for transient assay in tobacco protoplasts using pB-GFP::P85-P87::GUS and pB-GFP::P87–P85::GUS and for transient Agro-infiltration experiments using pK-GFP::P85–P87::GUS (GeneBank Accession no. KF661330) and pK-GFP::P87–P85::GUS. Below each construct a representative assay of transient GFP expression detected in fluorescence imaging of tobacco protoplast (bar represents 100 µm) and transient GUS expression detected histochemically by <i>Agrobacterium</i> infiltration assay in <i>N. benthamiana</i> leaf are shown for respective promoter <i>At4g35985</i> promoter (P85) and <i>At4g35985</i>7 promoter (P87) activities. Genetic elements: left and right T-DNA border (LT and RT, respectively), CaMV 35S terminator (35ST), green fluorescence protein gene (GFP), β-glucuronidase (GUS), 3′-terminator sequences of ribulose bisphosphate carboxylase small subunit (rbcST) and restriction enzymes <i>Eco</i>RI, <i>Hin</i>dIII, <i>Xho</i>I, <i>Sac</i>I, <i>Xba</i>I, <i>Cla</i>I used to assemble these expression constructs are shown.