Fig. 4.

Auxin inhibition of primary root growth and auxin induction of LR formation in Col and fwr mutant seedlings. (A) Four-day-old Col and fwr mutant seedlings were transferred onto IAA-free (control) or IAA-containing media, and incubated for an additional 3 d. Scale bar = 10 mm. Representative seedlings are shown for each treatment. (B) Root elongation of seedlings on IAA-containing media for 72 h. The error bars represent the SEM (n = 25). (C) LR number of seedlings grown on IAA-containing media for 72 h. The values for fwr mutants on hormone-free media (control) are 0.0 ± 0.0 (mean ± SEM). The error bars represent the SEM. The asterisks indicate a statistical difference between Col and the fwr mutant (*P < 0.01 by Student’s t-test). ns, not significant. n = 25. (D) LR density of seedlings on IAA-containing media for 72 h. The values of fwr mutants on hormone-free (control) and 0.01 µM IAA media is not determined due to a limited number of LR primordia (N.D.). The error bars represent the SEM. The asterisks indicate a statistical difference between Col and the fwr mutant (*P < 0.01 by Student’s t-test). ns, not significant. n = 25. Experiments were repeated twice, and similar results were obtained in each experiment.