Institute of Science and Technology (IST) Austria, Klosterneuburg, Austria.
Bioresources Unit, Center for Health & Bioresources, AIT Austrian Institute of Technology GmbH, Tulln, Austria.
EMBO J. 2021 Feb 1;40(3):e106862. doi: 10.15252/embj.2020106862. Epub 2021 Jan 5.
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.
土壤中必需的大量营养素氮的供应对植物的生长、发育起着至关重要的作用，并影响农业生产力。植物已经进化出不同的策略来感知和应对不均匀的氮分布。根系结构的调节，包括主根的生长和分枝，是植物适应以确保获得足够氮素的最基本策略之一。然而，对于协调根生长以响应不同氮源（如硝酸盐或铵盐）的直接分子途径，我们知之甚少。在这里，我们表明，通过两个相邻的根外层组织之间协调的生长素流来实现细胞分裂和伸长的生长同步。这种协调是通过硝酸盐依赖的 PIN2 生长素外排载体在一个以前未被描述的磷酸化位点上的去磷酸化来实现的，导致随后的 PIN2 横向化，从而调节相邻组织之间的生长素流。基于我们实验数据的动态计算机模型成功地再现了实验观察结果。我们的研究提供了机制上的见解，拓宽了我们对动态环境中根生长机制的理解。
