Root system architecture is an important determinant of below-ground resource capture and hence overall plant fitness. The plant hormone auxin plays a central role in almost every facet of root development from the cellular to the whole-root-system level. Here, using Arabidopsis as a model, we review the multiple gene signaling networks regulated by auxin biosynthesis, conjugation, and transport that underpin primary and lateral root development. We describe the role of auxin in establishing the root apical meristem and discuss how the tight spatiotemporal regulation of auxin distribution controls transitions between cell division, cell growth, and differentiation. This includes the localized reestablishment of mitotic activity required to elaborate the root system via the production of lateral roots. We also summarize recent discoveries on the effects of auxin and auxin signaling and transport on the control of lateral root gravitropic setpoint angle (GSA), a critical determinant of the overall shape of the root system. Finally, we discuss how environmental conditions influence root developmental plasticity by modulation of auxin biosynthesis, transport, and the canonical auxin signaling pathway.

中文翻译：

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生长素在根发育中的作用


根系结构是地下资源捕获以及植物整体适应性的重要决定因素。植物激素生长素在从细胞到整个根系统水平的根发育的几乎每个方面都发挥着核心作用。在这里，我们以拟南芥为模型，回顾了由生长素生物合成、接合和运输调节的多基因信号网络，这些网络支撑着初生根和侧根的发育。我们描述了生长素在建立根尖分生组织中的作用，并讨论了生长素分布的严格时空调节如何控制细胞分裂、细胞生长和分化之间的转变。这包括通过产生侧根来局部重建根系所需的有丝分裂活性。我们还总结了关于生长素和生长素信号传导和运输对侧根向地性设定角（GSA）控制影响的最新发现，GSA是根系整体形状的关键决定因素。最后，我们讨论环境条件如何通过调节生长素生物合成、运输和典型的生长素信号通路来影响根系发育可塑性。