Fig. 4

The relative expression level of auxin-response and signaling genes in PR tip and LRP initiation zone. A-C The relative expression level of auxin responsive genes ZmIAA2 (A), ZmIAA10 (B), and ZmIAA21 (C) in PR tip at 24 h, 48 h, and 72 h after LN and NN treatments. D-F The relative expression level of auxin responsive genes ZmIAA2 (D), ZmIAA10 (E), and ZmIAA21 (F) in LRP initiation zone at 24 h, 48 h, and 72 h after LN and NN treatments. G-I The relative expression level of auxin-signaling genes ZmARF7 (G), ZmARF19 (H), and ZmLBD29 (I) in LRP initiation zone at 24 h, 48 h, and 72 h after LN and NN treatments. Values with error bars represent mean ± SD (n = 3). The gene expression was calibrated to the expression of ZmUBC (ubiquitin C). The asterisks indicated significant differences between different treatments according to a Student's t test. **, P ≤ 0.01