Figure 7.

Root-to-Shoot Nitrate Transport Is Increased in nrt1.9 Mutants.

(A) and (C) ¹⁵N content in shoot and root of the wild type and nrt1.9 mutants.

(B) and (D) Shoot-to-root ¹⁵N ratio in the wild type and nrt1.9 mutants. The wild type and nrt1.9 mutants were grown in liquid medium with 5 mM NH₄NO₃ for 10 d and then labeled with 10 mM NH₄¹⁵NO₃ for 30 min.

¹⁵N concentration and ratio between shoots and roots (S/R) were analyzed and calculated relative to dry weight (DW) as described in Methods. Values in (A) to (D) are mean ± se. An asterisk indicates a significant difference (P < 0.05) compared with the values of the wild type. Similar results were shown in three independent experiments. Each experiment was performed in four replicates, and each replicate contained 30 seedlings.