Effect of WAT1: GFP protein activity on cellular auxin homeostasis. (A) Preferential WAT1:GFP localization at the tonoplast (arrowheads). Bar = 10 μm. (b,c) Lower DR5rev:mRFP intensity in cells expressing 35S:WAT1:GFP than control cells co-expressing DR5rev:mRFP and 35S:GFP:GFP. (B) Graph represents the relative average mean gray values (MGV) of the DR5rev:mRFP signal intensity. Error bars represent standard error (n = 60). Statistical significance was evaluated with the unpaired student T-test (* P < 0.05, ** P < 0.01, *** P < 0.0001). (C) Graph depicts the change in relative number of transformed cells displaying a low (-), medium (+), high (++), and very high (+++) DR5rev:mRFP signal intensity between the two samples (for detailed description of the quantification, see Additional file 1: Figure S2). Error bars represent standard error (n = 3 repetitions with at least 50 counted cells). Statistical significance was evaluated with the ANOVA test; the P-value is indicated.