Figure 4.

Lateral Root Development in Wild-Type and irt1 Plants in Response to Localized Fe Supply.

Density (A) and average length (B) of lateral roots in wild-type (Col-0) and irt1 mutant plants as affected by the Fe concentration supplied to the middle segment. Wild-type and irt1 seeds were germinated on Fe-free, half-strength MS medium for 7 d. Seedlings were then transferred to segmented agar plates supplied with Fe in the middle segment at the indicated concentrations. After 15 d, the number and average length of visible lateral roots (>0.5 mm) in the middle segment were determined by image analysis. Shoot chlorophyll concentrations were determined after 15 d of growth (C). Bars represent means ± se; n = 7 replicates consisting of three plants. Different letters indicate significant differences among means (P < 0.05 by Tukey’s test).