Nitrate is an essential nutrient and signaling molecule for plant growth. Plants sense intracellular nitrate to adjust their metabolic and growth responses. Here we identify the primary nitrate sensor in plants. We found that mutation of all seven Arabidopsis NIN-like protein (NLP) transcription factors abolished plants’ primary nitrate responses and developmental programs. Analyses of NIN-NLP7 chimeras and nitrate binding revealed that NLP7 is derepressed upon nitrate perception via its amino terminus. A genetically encoded fluorescent split biosensor, mCitrine-NLP7, enabled visualization of single-cell nitrate dynamics in planta. The nitrate sensor domain of NLP7 resembles the bacterial nitrate sensor NreA. Substitutions of conserved residues in the ligand-binding pocket impaired the ability of nitrate-triggered NLP7 to control transcription, transport, metabolism, development, and biomass. We propose that NLP7 represents a nitrate sensor in land plants.

中文翻译：

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NIN 样蛋白 7 转录因子是植物硝酸盐传感器

硝酸盐是植物生长必需的营养素和信号分子。植物感知细胞内硝酸盐以调整它们的代谢和生长反应。在这里，我们确定了植物中主要的硝酸盐传感器。我们发现所有七个突变拟南芥NIN 样蛋白 (NLP) 转录因子废除了植物的初级硝酸盐反应和发育程序。对 NIN-NLP7 嵌合体和硝酸盐结合的分析表明，NLP7 通过其氨基末端对硝酸盐的感知被去阻遏。基因编码的荧光分裂生物传感器 mCitrine-NLP7 能够实现足底单细胞硝酸盐动力学的可视化。NLP7 的硝酸盐传感器域类似于细菌硝酸盐传感器 NreA。配体结合口袋中保守残基的取代削弱了硝酸盐触发的 NLP7 控制转录、运输、代谢、发育和生物量的能力。我们建议 NLP7 代表陆地植物中的硝酸盐传感器。