Effect of WRKY28 and WRKY46 on the expression of endogenous Arabidopsis genes. Expression of ICS1, PBS3, WRKY28, WRKY46 and four household genes in Arabidopsis protoplasts was measured by qRT-PCR. Expression of each gene was measured in protoplasts transfected with the empty pRT101 vector (minus sign) or with the pRT101 vector containing 35S::WRKY28 (W28) or 35S::WRKY46 (W46) expression constructs. Bars represent the average level of mRNA accumulation observed in three experiments. mRNA levels in protoplasts transfected with the empty pRT101 vector were taken as 100%. The control represents the average of the data obtained with the four household genes. Error bars represent the SEM.