Figure 9.

Excess phosphate supply reduced root apical meristem size of WT but not in ethylene- insensitive mutants. WT and ethylene insensitive (etr1–3, ein4, ein2-T) or sensitive mutant (ctr1–1) were grown as described in the caption to Fig. 1. A 5 mm section from the tip of primary root was cut and mounted on a slide with diluted Visikol in 10% glycerol, and root cells were visualized under the DIC filter. Root meristem size was measured by counting the number of meristematic cortex cells between the quiescent center (QC) and the first elongated cell. White arrows mark the QC and first elongated cortex cells in a representative picture of WT and ein2-T mutant (a). Data are presented for the number of cortical cells (b), and the ratio of RAM size (cell number) of plants grown at P₂₀ to P_1.25 conditions, as shown in (c). Values are means ± SE, and n = 15 (b,c). Bars with different alpha letter differ significantly (P ≤ 0.05–0.001) according to two-way ANOVA (b), and one-way ANOVA (c) with Bonferroni’s posttest.