González-Moro María Begoña, González-Moro Itziar, de la Peña Marlon, Estavillo José María, Aparicio-Tejo Pedro M, Marino Daniel, González-Murua Carmen, Vega-Mas Izargi
Department of Plant Biology and Ecology, University of the Basque Country (UPV/EHU), Bilbao, Spain.
Instituto Multidisciplinar de Biología Aplicada (IMAB), Universidad Pública de Navarra, Pamplona, Spain.
Front Plant Sci. 2021 Jan 27;11:632285. doi: 10.3389/fpls.2020.632285. eCollection 2020.
Nitrate and ammonium are the main nitrogen sources in agricultural soils. In the last decade, ammonium (NH ), a double-sided metabolite, has attracted considerable attention by researchers. Its ubiquitous presence in plant metabolism and its metabolic energy economy for being assimilated contrast with its toxicity when present in high amounts in the external medium. Plant species can adopt different strategies to maintain NH homeostasis, as the maximization of its compartmentalization and assimilation in organic compounds, primarily as amino acids and proteins. In the present study, we report an integrative metabolic response to ammonium nutrition of seven plant species, belonging to four different families: Gramineae (ryegrass, wheat, ), Leguminosae (clover), Solanaceae (tomato), and Brassicaceae (oilseed rape, ). We use principal component analysis (PCA) and correlations among metabolic and biochemical data from 40 experimental conditions to understand the whole-plant response. The nature of main amino acids is analyzed among species, under the hypothesis that those Asn-accumulating species will show a better response to ammonium nutrition. Given the provision of carbon (C) skeletons is crucial for promotion of the nitrogen assimilation, the role of different anaplerotic enzymes is discussed in relation to ammonium nutrition at a whole-plant level. Among these enzymes, isocitrate dehydrogenase (ICDH) shows to be a good candidate to increase nitrogen assimilation in plants. Overall, metabolic adaptation of different carbon anaplerotic activities is linked with the preference to synthesize Asn or Gln in their organs. Lastly, glutamate dehydrogenase (GDH) reveals as an important enzyme to surpass C limitation during ammonium assimilation in roots, with a disparate collaboration of glutamine synthetase (GS).
硝酸盐和铵盐是农业土壤中的主要氮源。在过去十年中，铵（NH₄⁺）这种具有双面性的代谢产物引起了研究人员的广泛关注。它在植物新陈代谢中普遍存在，以及其被同化时的代谢能量经济性，与它在外部介质中含量过高时的毒性形成了鲜明对比。植物物种可以采取不同策略来维持铵的内稳态，比如将其在有机化合物中（主要是作为氨基酸和蛋白质）的区室化和同化作用最大化。在本研究中，我们报告了属于四个不同科的七种植物对铵营养的综合代谢响应：禾本科（黑麦草、小麦）、豆科（三叶草）、茄科（番茄）和十字花科（油菜）。我们使用主成分分析（PCA）以及来自40种实验条件下的代谢和生化数据之间的相关性，来了解整株植物的响应。在假设那些积累天冬酰胺（Asn）的物种对铵营养会有更好响应的前提下，分析了不同物种间主要氨基酸的性质。鉴于提供碳（C）骨架对于促进氮同化至关重要，在整株植物水平上讨论了不同的回补酶与铵营养的关系。在这些酶中，异柠檬酸脱氢酶（ICDH）显示是增加植物氮同化的一个良好候选者。总体而言，不同碳回补活性的代谢适应性与它们器官中合成天冬酰胺（Asn）或谷氨酰胺（Gln）的偏好相关。最后，谷氨酸脱氢酶（GDH）显示是根系在铵同化过程中克服碳限制的一种重要酶，谷氨酰胺合成酶（GS）与之有不同的协作方式。
