Figure 3.

NO₃⁻ influx, NRT2.1, and NAR2.1 mRNA level in roots of wild-type and transgenic plants in response to 10 mm KNO₃. Plants were grown in vitro during 8 d on 0.2 mm KNO₃ (white bars) or 10 mm KNO₃ (gray bars). A, Root NRT2.1 expression quantified by Q-PCR. Values are means of two biological replicates ± sd. B, Root NO₃⁻ influx measured at the external concentration of 0.2 mm ¹⁵NO₃⁻. Values are means of 12 replicates ± sd. C, Root NAR2.1 expression quantified by Q-PCR. Values are means of two biological replicates ± sd. Differences between plants grown on 0.2 mm KNO₃ and 10 mm KNO₃ are significant at *P < 0.05, **P < 0.01, ***P < 0.001 (Student’s t test).