Roots vary their permeability to aid radial transport of solutes towards xylem vessels in response to nutritional cues. Nitrogen (N) depletion was previously shown to induce early suberization of endodermal cell walls and reduce hydraulic conductivity of barley roots suggesting reduced apoplastic transport of ions (Armand et al., 2019). Suberization may also limit transcellular ion movement by blocking access to transporters (Barberon et al., 2016). The aim of this study was to confirm that N depletion induced suberization in the roots of barley and demonstrate that this was a specific effect in response to NO3- depletion. Furthermore, in roots with early and enhanced suberization, we assessed their ability for transporter-mediated NO3- influx. N depletion induced lateral root elongation and early and enhanced endodermal suberization of the seminal root of each genotype. Both root to shoot NO3- translocation and net N uptake was half that of plants supplied with steady-state NO3-. Genes with predicted functions in suberin synthesis (HvHORST) and NO3- transport (HvNRT2.2) were induced under N-deplete conditions. N-deplete roots had a higher capacity for high-affinity NO3- influx in early suberized roots than under optimal NO3-. In conclusion, NO3- depletion induced early and enhanced suberization in the roots of barley, however, suberization did not restrict transcellular NO3- transport.

中文翻译：

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氮耗竭增强内胚层木栓化而不限制转运蛋白介导的根 NO3-流入

根改变其渗透性以帮助响应营养线索向木质部血管径向运输溶质。先前已证明氮 (N) 消耗会诱导内胚层细胞壁的早期松质化并降低大麦根的导水率，这表明离子的质外体运输减少（Armand 等，2019）。Suberization 还可以通过阻断转运蛋白的通路来限制跨细胞离子运动（Barberon 等，2016）。本研究的目的是确认 N 消耗会诱导大麦根部的木栓化，并证明这是对 NO3 消耗的特定反应。此外，在具有早期和增强的木栓化的根中，我们评估了它们转运蛋白介导的 NO3 流入的能力。氮耗竭诱导侧根伸长和每个基因型精根的早期和增强的内胚层松质化。根到芽的 NO3- 易位和净 N 吸收都是提供稳态 NO3- 的植物的一半。在 N-耗尽条件下诱导在木栓质合成 (HvHORST) 和 NO3-转运 (HvNRT2.2) 中具有预测功能的基因。与最佳 NO3- 相比，贫氮根在早期松质化根中具有更高的高亲和力 NO3- 流入能力。总之，NO3- 消耗诱导大麦根部的早期和增强的木栓化作用，然而，木栓化作用不限制跨细胞 NO3- 转运。在 N-耗尽条件下诱导在木栓质合成 (HvHORST) 和 NO3-转运 (HvNRT2.2) 中具有预测功能的基因。与最佳 NO3- 相比，贫氮根在早期松质化根中具有更高的高亲和力 NO3- 流入能力。总之，NO3- 消耗诱导大麦根部的早期和增强的木栓化作用，然而，木栓化作用并不限制跨细胞 NO3- 转运。在 N-耗尽条件下诱导在木栓质合成 (HvHORST) 和 NO3-转运 (HvNRT2.2) 中具有预测功能的基因。与最佳 NO3- 相比，贫氮根在早期松质化根中具有更高的高亲和力 NO3- 流入能力。总之，NO3- 消耗诱导大麦根部的早期和增强的木栓化作用，然而，木栓化作用不限制跨细胞 NO3- 转运。