Fig. 1

The GAF domain is required for the transport of AtNLP7 from the nucleus to the cytoplasm in response to nitrate deficiency and affects plant growth. A Domain structures schematic of the GFP fusions for the AtNLP7 derivatives. NLP7: construct used to express the full-length AtNLP7 protein driven by CaMV 35S promoter. NLP7^∆NES: construct used to express the AtNLP7 protein with deleted nuclear export sequence driven by CaMV 35S promoter. NLP7^∆GAF−1: construct used to express the AtNLP7 protein with deleted GAF domain driven by CaMV 35S promoter. NLP7^∆GAF−2: construct used to express the AtNLP7 protein with deleted region from GAF domain to RWP-RK domain driven by CaMV 35S promoter. NLP7.^∆PB1: construct used to express the AtNLP7 protein with deleted PB1 domain driven by CaMV 35S promoter. Each construct contained the GFP in the C-terminal. B Nucleocytosolic shuttling of AtNLP7 derivatives. Confocal imaging was performed on nlp7-1 seedlings expressing different fusion proteins. Seedlings growing on medium with 10 mM KNO₃ for five days were transferred to N-free medium for two days then treated with 10 mM KNO₃ or KCl for one hour. Scale bars, 20 μm. C Plants grown with a density of 20 plants per line on 1 mM (LN) or 10 mM (HN) KNO₃ modified MS medium for 10 days. Scale bars, 0.5 cm. D Image of 3-week-old AtNLP7 derivate lines, nlp7-1 and WT plants grew in soil. Scale bars, 1 cm. E–G The shoot fresh weight (E), chlorophyll a (F) and b (G) contents of the 10-day-old plants grown as in C. Values are the mean ± SD of three independent replications each containing 20 plants per genotype. P values are from the one-way ANOVA (The letters indicate significant differences. P < 0.05). H Shoot fresh weight of the plants grown as in D. Values are the mean ± SD of four independent replications each containing 6 plants per genotype (The letters indicate significant differences. P < 0.05)