S601 of SLAH3 plays a role in regulating nitrate-dependent alleviation of ammonium toxicity. A, 20-d-old plants of Col-0, slah3-4 and slah3-4 complemented with different variants of SLAH3 sequences are presented under different culture conditions. The phospho-dead variant (S601A) and phospho-mimetic variant (S601D) were driven by its native promoter. White scale = 2 cm. B, The statistical analyses of fresh weight on the plants presented in (A). Fresh weights of five seedlings per plate for each line were analyzed. Bars indicate se, n = 3. C, The statistical analyses of main root length on the plants presented in (A). Root lengths of five seedlings per plate for each line were analyzed. Bars indicate se, n = 3. Statistical analyses were performed by two-way ANOVA analysis with Dunnett’s multiple comparisons test. *P < 0.05; **P < 0.01. S, Sucrose.