Department of Botany and Plant Sciences, University of California Riverside, Riverside, CA 9250, USA.
Genetics Department, Faculty of Agriculture, Menoufia University, Shebin El-Kom 32511, Egypt.
Biomolecules. 2023 Sep 25;13(10):1443. doi: 10.3390/biom13101443.
Plants uptake and assimilate nitrogen from the soil in the form of nitrate, ammonium ions, and available amino acids from organic sources. Plant nitrate and ammonium transporters are responsible for nitrate and ammonium translocation from the soil into the roots. The unique structure of these transporters determines the specificity of each transporter, and structural analyses reveal the mechanisms by which these transporters function. Following absorption, the nitrogen metabolism pathway incorporates the nitrogen into organic compounds via glutamine synthetase and glutamate synthase that convert ammonium ions into glutamine and glutamate. Different isoforms of glutamine synthetase and glutamate synthase exist, enabling plants to fine-tune nitrogen metabolism based on environmental cues. Under stressful conditions, nitric oxide has been found to enhance plant survival under drought stress. Furthermore, the interaction between salinity stress and nitrogen availability in plants has been studied, with nitric oxide identified as a potential mediator of responses to salt stress. Conversely, excessive use of nitrate fertilizers can lead to health and environmental issues. Therefore, alternative strategies, such as establishing nitrogen fixation in plants through diazotrophic microbiota, have been explored to reduce reliance on synthetic fertilizers. Ultimately, genomics can identify new genes related to nitrogen fixation, which could be harnessed to improve plant productivity.
植物以硝酸盐、铵离子和有机来源的可利用氨基酸的形式从土壤中吸收和同化氮。植物硝酸盐和铵离子转运蛋白负责将硝酸盐和铵离子从土壤中转运到根部。这些转运蛋白的独特结构决定了每个转运蛋白的特异性，结构分析揭示了这些转运蛋白的作用机制。吸收后，氮代谢途径通过谷氨酰胺合成酶和谷氨酸合酶将氮结合到有机化合物中，将铵离子转化为谷氨酰胺和谷氨酸。谷氨酰胺合成酶和谷氨酸合酶存在不同的同工型，使植物能够根据环境线索精细调节氮代谢。在胁迫条件下，已经发现一氧化氮可以增强植物在干旱胁迫下的生存能力。此外，还研究了植物中盐度胁迫和氮可用性之间的相互作用，发现一氧化氮是对盐胁迫反应的潜在调节剂。相反，过量使用硝酸盐肥料会导致健康和环境问题。因此，已经探索了通过固氮微生物建立植物固氮的替代策略，以减少对合成肥料的依赖。最终，基因组学可以鉴定与固氮相关的新基因，这些基因可以被利用来提高植物的生产力。
