Institut Jean-Pierre Bourgin, Unité Mixte de Recherche 1318 INRA-Agro-ParisTech, F-78026 Versailles cedex, France.
Plant Physiol. 2011 Nov;157(3):1255-82. doi: 10.1104/pp.111.179838. Epub 2011 Sep 7.
Nitrogen (N) is an essential macronutrient for plants. N levels in soil vary widely, and plants have developed strategies to cope with N deficiency. However, the regulation of these adaptive responses and the coordinating signals that underlie them are still poorly understood. The aim of this study was to characterize N starvation in adult Arabidopsis (Arabidopsis thaliana) plants in a spatiotemporal manner by an integrative, multilevel global approach analyzing growth, metabolites, enzyme activities, and transcript levels. We determined that the remobilization of N and carbon compounds to the growing roots occurred long before the internal N stores became depleted. A global metabolite analysis by gas chromatography-mass spectrometry revealed organ-specific differences in the metabolic adaptation to complete N starvation, for example, for several tricarboxylic acid cycle intermediates, but also for carbohydrates, secondary products, and phosphate. The activities of central N metabolism enzymes and the capacity for nitrate uptake adapted to N starvation by favoring N remobilization and by increasing the high-affinity nitrate uptake capacity after long-term starvation. Changes in the transcriptome confirmed earlier studies and added a new dimension by revealing specific spatiotemporal patterns and several unknown N starvation-regulated genes, including new predicted small RNA genes. No global correlation between metabolites, enzyme activities, and transcripts was evident. However, this multilevel spatiotemporal global study revealed numerous new patterns of adaptation mechanisms to N starvation. In the context of a sustainable agriculture, this work will give new insight for the production of crops with increased N use efficiency.
氮（N）是植物必需的大量营养素。土壤中的 N 含量差异很大，植物已经形成了应对 N 缺乏的策略。然而，这些适应反应的调节以及它们所依据的协调信号仍然知之甚少。本研究旨在通过综合、多层次的全局方法分析生长、代谢物、酶活性和转录水平，以时空方式描述成年拟南芥（Arabidopsis thaliana）植株的 N 饥饿。我们确定，在内部 N 储存耗尽之前，N 和碳化合物就会被重新分配到生长中的根中。通过气相色谱-质谱联用的全局代谢物分析，揭示了对完全 N 饥饿的代谢适应的器官特异性差异，例如几种三羧酸循环中间体，但也包括碳水化合物、次生产物和磷酸盐。中心 N 代谢酶的活性和硝酸盐摄取能力适应 N 饥饿，通过促进 N 再利用和在长期饥饿后增加高亲和力硝酸盐摄取能力来适应。转录组的变化证实了早期的研究，并通过揭示特定的时空模式和几个未知的 N 饥饿调节基因，包括新预测的小 RNA 基因，增加了一个新的维度。代谢物、酶活性和转录之间没有明显的全局相关性。然而，这种多层次的时空全局研究揭示了许多适应 N 饥饿的新机制模式。在可持续农业的背景下，这项工作将为提高作物 N 利用效率提供新的见解。
