Overexpression of ZmNRAMP2 enhances the tolerance of transgenic maize plants to Mn deficiency. A, Relative expression of ZmNRAMP2 in the two independent overexpression lines (OE-1 and OE-4) and WT (ND101). Data are presented as means ± sd (n = 3, biological replicates). Significant difference was indicated at **P < 0.01 by Student’s t test. B, Dynamic changes of F_v/F_m in the youngest fully emerged leaf of the ZmNRAMP2-overexpressing lines (OE-1 and OE-4) and WT (ND101) from 12 to 17 DAT. Maize seedlings were grown in nutrient solution supplied with 1-µM Mn (+Mn) or without Mn (−Mn). Data are presented as means ± sd (n = 6, biological replicates). C and D, Mn concentrations of shoot and root respectively, E, Mn contents of shoot and root, and F, Mn distribution between root and shoot of the ZmNRAMP2-overexpressing lines (OE-1 and OE-4) and WT (ND101) plants grown under contrasted Mn regimes. Maize seedlings were grown in nutrient solution supplied with 1-µM Mn (+Mn) or without Mn (−Mn) for 17 days. Data are presented as means ± sd (n = 6, biological replicates). Significant difference was indicated at *P < 0.05 and **P < 0.01 by Student’s t test (labeling in red and blue for shoots and roots, respectively), and ns, not significant.