Transactivation of ICS1::GUS genes with mutations in WRKY28 binding sites. Protoplasts were transfected with 2 μg of wild-type promoter::GUS constructs or promoter::GUS constructs containing the mutations m1, m2 or m1+2 as indicated in Figure 4B. W28, cotransfection with 6 μg of expression vector pRT101 containing 35S::WRKY28. Minus signs, cotransfection with 6 μg of empty expression vector. The bars represent the percentage of GUS activity from triple experiments relative to that of the protoplasts cotransfected with the promoter::GUS construct and an empty expression vector, which was set to 100%. Error bars represent the SEM.