NRT1.1 Regulates Nitrate Allocation and Cadmium Tolerance in Arabidopsis.

Abiotic stress induces nitrate (NO ) allocation to roots, which increases stress tolerance in plants. NRT1.1 is broadly involved in abiotic stress tolerance in plants, but the relationship between NRT1.1 and NO allocation under stress conditions is unclear. In this study, we found that Arabidopsis wild-type Col-0 was more cadmium (Cd)-tolerant than the mutant at 20 μM CdCl. Cd exposure repressed but upregulated in roots of Col-0 plants, resulting in increased NO allocation to roots and higher [NO ] root-to-shoot (R:S) ratios. Interestingly, () was upregulated by Cd stress in Col-0 but not in . Under Cd stress, and mutants exhibited similar phenotypes and NO allocation patterns as observed in the mutant, but overexpression of in Col-0 and increased the [NO ] R:S ratio and restored Cd stress tolerance. Our results indicated that and regulated Cd stress-induced NO allocation to roots and that functioned downstream of . Cd uptake did not differ between Col-0 and , but Cd allocation to roots was higher in Col-0 than in . Stressed Col-0 plants increased Cd and NO allocation to root vacuoles, which reduced their cytosolic allocation and transport to the shoots. Our results suggest that NRT1.1 regulates NO allocation to roots by coordinating Cd accumulation in root vacuoles, which facilitates Cd detoxification.