Transactivation of ICS1 and PBS3 promoter::GUS reporter genes by WRKY28 and WRKY46 in Arabidopsis protoplasts. The fusions contained promoter sequences of 960 bp and 1000 bp upstream of the transcription start sites of the ICS1 or PBS3 genes, respectively. Protoplasts were transfected with 6 μg of vector pRT101 containing 35S::WRKY28 (W28) or 35S::WRKY46 (W46) inserts, or with the empty vector (minus sign). The left three bars, correspond to the protoplasts co-transfected with 2 μg of the ICS1::GUS construct, the right three bars, to protoplasts co-transfected with 2 μg of the PBS3::GUS gene. The bars represent the average relative GUS expression observed in four experiments. GUS expression induced in the presence of the empty pRT101 vector was taken as 100%. Error bars represent the SEM.