(F) PHR1 activates RALF promoters in plants. Depicted RALF promoter-LUC fusions (RALF24 as a negative control) were co-expressed together with 35S promoter-driven PHR1 or an empty vector control in Arabidopsis protoplasts. The relative LUC/REN reporter activity was quantified. The data shown indicate the means ± SDs (n = 3, n refers to technical replicates); n.s., not significant; *, p < 0.05; **, p < 0.01 (Student's t test). Data information: All experiments were repeated three times with similar results. 