Figure 8.

Nitrate (${\text{NO}}_3^{-}$) transport by ZmSUGCAR1 in oocytes and ${\text{NO}}_3^{-}$ accumulation in the endosperm. A, The pH dependence of ZmSUGCAR1-mediated nitrate uptake in oocytes. Oocytes injected with water were used as a negative control. B and C, Nitrate uptake activity of ZmSUGCAR1 in oocytes under low (B) or high (C) nitrate conditions. Oocytes injected with AtNPF6.3 and water were used as positive and negative controls, respectively. D, Nitrate concentration in the endosperm of WT and zmsugcar1-1 at 14 and 20 DAP. E and F, Competition assays between sugar and nitrate (${\text{NO}}_3^{-}$) uptake by ZmSUGCAR1. Oocytes injected with water were used as a negative control. P < 0.05 indicated significant differences.