The enzymatic controlled metabolic processes in cells occur at their optimized pH ranges, therefore cellular pH homeostasis is fundamental for life. In plants, the nitrogen (N) source for uptake and assimilation, mainly in the forms of nitrate (NO₃^–) and ammonium (NH₄⁺) quantitatively dominates the anion and cation equilibrium and the pH balance in cells. Here we review ionic and pH homeostasis in plant cells and regulation by N source from the rhizosphere to extra- and intracellular pH regulation for short- and long-distance N distribution and during N assimilation. In the process of N transport across membranes for uptake and compartmentation, both proton pumps and proton-coupled N transporters are essential, and their proton-binding sites may sense changes of apoplastic or intracellular pH. In addition, during N assimilation, carbon skeletons are required to synthesize amino acids, thus the combination of NO₃^– or NH₄⁺ transport and assimilation results in different net charge and numbers of protons in plant cells. Efficient maintenance of N-controlled cellular pH homeostasis may improve N uptake and use efficiency, as well as enhance the resistance to abiotic stresses.

中文翻译：

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植物氮的吸收和同化：细胞 pH 稳态的调节。


细胞中酶控制的代谢过程发生在其优化的 pH 范围内，因此细胞 pH 稳态是生命的基础。在植物中，吸收和同化的氮（N）源主要以硝酸盐（NO ₃ ^- ）和铵（NH ₄ ⁺ ）的形式存在，在数量上主导着细胞内的阴离子和阳离子平衡以及pH平衡。在这里，我们回顾了植物细胞中的离子和 pH 稳态，以及氮源从根际到细胞外和细胞内 pH 调节的调节，以实现短距离和长距离氮分布以及氮同化过程。在氮跨膜转运以进行吸收和分隔的过程中，质子泵和质子耦合氮转运蛋白都是必不可少的，它们的质子结合位点可以感知质外体或细胞内pH的变化。此外，在N同化过程中，需要碳骨架来合成氨基酸，因此NO ₃ ^–或NH ₄ ⁺运输与同化的结合导致植物细胞中不同的净电荷和质子数。有效维持氮控制的细胞 pH 稳态可以提高氮的吸收和利用效率，并增强对非生物胁迫的抵抗力。