Figure 4.

Growth responses of prce seedlings to changes in Pi availability. A, Root-to-shoot ratios of P-replete (black bars) and P-limited (gray bars) seedlings (Supplemental Data Set S2B). Lines with a significant ratio increase under P limitation (P < 0.001) are in the wild-type (WT)-like and pho2-like groups. The phr1-like group showed no P-dependent shift in the root-to-shoot ratio. B and C, Shoot (B) and root (C) biomass gain in seedlings 5 d after transfer to either P-replete (black bars) or P-limited (gray bars) medium. Shoot biomass gains showed significant differences between treatments (P < 0.001) across genotypes. Treatment differences (P < 0.001) in root biomass gain are highlighted in red. B, P-limited shoots of s6k2-like mutants were able to sustain growth, while cbl1-like mutants had higher shoot biomass gain than the wild type irrespective of Pi supply. C, Roots of seedlings in the cbl1-like group showed a hypersensitive response to Pi limitation, while P-limited roots of prce1 and s6k2 accumulated more biomass than P-replete roots. Data shown are averages ± se; n = 3. Significant differences from Col-0 were identified by two-way ANOVA followed by Tukey’s multiple comparison test and are indicated with a hash (^#, P < 0.001) or an asterisk (*, P < 0.05). FW, Fresh weight.