The root system of barley plants is composed of embryogenic, seminal roots, as well as lateral and nodal roots that are formed post-embryonically from seminal roots and from the basal part of shoots, respectively. Due to their distinct developmental origin, seminal and nodal roots may differ in function during plant development, however, a clear comparison between these two root types has not yet been undertaken. In this study, anatomical, proteomic and physiological traits were compared between seminal and nodal roots of similar developmental stage. Nodal roots have larger diameter, larger metaxylem area and a larger number of metaxylem vessels than seminal roots. Proteome profiling uncovered a set of root type-specific proteins, including proteins related to cell wall and cytoskeleton organization, which could potentially be implicated with differential metaxylem development. We also found that nodal roots have higher levels of auxin, which is known to trigger metaxylem development. At millimolar nitrate supply nodal roots had approximately twofold higher nitrate uptake and root-to-shoot translocation capacities than seminal roots, whereas no differences were found at micromolar nitrate supply. Since these marked differences were not reflected by the transcript levels of low-affinity nitrate transporter genes, we hypothesize that the larger metaxylem volume of nodal roots enhances predominantly the low-affinity uptake and translocation capacities of nutrients that are transported with the bulk flow of water, like nitrate.

中文翻译：

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大麦的精子和节根在解剖学，蛋白质组和硝酸盐吸收能力上的差异。

大麦植物的根系由胚根，精根以及侧根和节根组成，这些根分别由芽后的根和芽的基础部分形成。由于它们独特的发育起源，在植物发育过程中，精根和节根的功能可能有所不同，但是，尚未对这两种根类型进行明确的比较。在这项研究中，比较了处于相似发育阶段的精根和结根之间的解剖学，蛋白质组学和生理学特征。与精根相比，节根具有更大的直径，更大的后木质部面积和更多的后木质部血管。蛋白质组分析发现了一组根类型特异性蛋白，包括与细胞壁和细胞骨架组织有关的蛋白，这可能与差异性木质部异位发育有关。我们还发现，节根具有较高的生长素水平，已知该水平会引发后生木质部的发育。在毫摩尔硝酸盐供应下，结根的硝酸盐吸收量和根尖向茎的转运能力比精根高约两倍，而在微摩尔硝酸盐供应下没有发现差异。由于这些显着差异并未通过低亲和力硝酸盐转运蛋白基因的转录水平反映出来，因此我们推测，较大根结节的木质部木质部的体积主要增强了随大量水运输的养分的低亲和力吸收和转运能力。 ，像硝酸盐。众所周知，它会触发甲状旁腺的发育。在毫摩尔硝酸盐供应下，结根的硝酸盐吸收量和根尖向茎的转运能力比精根高约两倍，而在微摩尔硝酸盐供应下没有发现差异。由于这些显着差异并未通过低亲和力硝酸盐转运蛋白基因的转录水平反映出来，因此我们推测，较大根结节的木质部木质部的体积主要增强了随大量水运输的养分的低亲和力吸收和转运能力。 ，像硝酸盐。众所周知，它会触发甲状旁腺的发育。在毫摩尔硝酸盐供应下，节根的硝酸盐吸收量和根茎向易位能力比精根高大约两倍，而在微摩尔硝酸盐供应下没有发现差异。由于这些显着差异并未通过低亲和力硝酸盐转运蛋白基因的转录水平反映出来，因此我们推测，较大根结节的木质部木质部的体积主要增强了随大量水运输的养分的低亲和力吸收和转运能力。 ，像硝酸盐。