Figure 4.

Effect of cytokinin on repression of Pi starvation-responsive IPS1-GUS in split root assays. Ten-day-old transgenic plants harboring the IPS1-GUS gene (Martín et al., 2000) were Pi starved for 2 d, then transferred to split plates with the compartments containing media with the compositions as indicated and, after 3 d, histochemical analysis of GUS activity was performed. A, The compartments had Pi-sufficient (+P) or Pi-deficient (−P) media. B, The compartments had media lacking Pi, but each was supplemented or not with 10 μm kinetin (kin).