Availability of the essential macronutrient nitrogen in soil plays a critical role in plant growth, development, and impacts agricultural productivity. Plants have evolved different strategies for sensing and responding to heterogeneous nitrogen distribution. Modulation of root system architecture, including primary root growth and branching, is among the most essential plant adaptions to ensure adequate nitrogen acquisition. However, the immediate molecular pathways coordinating the adjustment of root growth in response to distinct nitrogen sources, such as nitrate or ammonium, are poorly understood. Here, we show that growth as manifested by cell division and elongation is synchronized by coordinated auxin flux between two adjacent outer tissue layers of the root. This coordination is achieved by nitrate‐dependent dephosphorylation of the PIN2 auxin efflux carrier at a previously uncharacterized phosphorylation site, leading to subsequent PIN2 lateralization and thereby regulating auxin flow between adjacent tissues. A dynamic computer model based on our experimental data successfully recapitulates experimental observations. Our study provides mechanistic insights broadening our understanding of root growth mechanisms in dynamic environments.

中文翻译：

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通过氮源限定的极性生长素运输调节来调节植物根系生长


土壤中必需大量营养元素氮的可用性对于植物生长、发育并影响农业生产力起着至关重要的作用。植物已经进化出不同的策略来感知和响应异质氮分布。根系结构的调节，包括初生根的生长和分枝，是确保获得足够氮的最重要的植物适应措施之一。然而，人们对协调根系生长调节以响应不同氮源（例如硝酸盐或铵）的直接分子途径知之甚少。在这里，我们表明，细胞分裂和伸长所表现的生长是通过根的两个相邻外组织层之间协调的生长素通量来同步的。这种协调是通过 PIN2 生长素流出载体在先前未表征的磷酸化位点上进行硝酸盐依赖性去磷酸化来实现的，导致随后的 PIN2 侧化，从而调节相邻组织之间的生长素流动。基于我们的实验数据的动态计算机模型成功地概括了实验观察结果。我们的研究提供了机械见解，拓宽了我们对动态环境中根系生长机制的理解。