Figure 1.

Characterization of Arabidopsis transgenic lines expressing NRT2.1 under the control of the 35S promoter. Wild type (WT), nrt2.1-2 knockout mutant (KO), and three transgenic lines (L5, L6, and L10) were grown in vitro during 8 d on 0.2 mm KNO₃ as N source. A, Primary root growth after 8 d. B, Root NRT2.1 expression quantified by quantitative (Q)-PCR. Values are means of two biological replicates ± sd. C, Dry weight (DW) of 8-d-old plants. Values are means of six replicates ± sd. D, Total N contents quantified after 8 d of growth. Values are means of six replicates ± sd. E, Root NO₃⁻ influx measured at the external concentration of 0.2 mm ¹⁵NO₃⁻. Values are means of 12 replicates ± sd. Differences between WT/transformants and the KO mutant are significant at *P < 0.05, **P < 0.01, ***P < 0.001 (Student’s t test).