Laboratory of Molecular and Cell Biology, Institute of Biology, University of Neuchâtel, 2000 Neuchâtel, Switzerland.
IPSiM, University of Montpellier, CNRS, INRAE, Institut Agro, 34060 Montpellier, France.
Biol Open. 2024 Sep 15;13(9). doi: 10.1242/bio.060531. Epub 2024 Sep 2.
The root system of plants is a vital part for successful development and adaptation to different soil types and environments. A major determinant of the shape of a plant root system is the formation of lateral roots, allowing for expansion of the root system. Arabidopsis thaliana, with its simple root anatomy, has been extensively studied to reveal the genetic program underlying root branching. However, to get a more general understanding of lateral root development, comparative studies in species with a more complex root anatomy are required. Here, by combining optimized clearing methods and histology, we describe an atlas of lateral root development in Brachypodium distachyon, a wild, temperate grass species. We show that lateral roots initiate from enlarged phloem pole pericycle cells and that the overlying endodermis reactivates its cell cycle and eventually forms the root cap. In addition, auxin signaling reported by the DR5 reporter was not detected in the phloem pole pericycle cells or young primordia. In contrast, auxin signaling was activated in the overlying cortical cell layers, including the exodermis. Thus, Brachypodium is a valuable model to investigate how signaling pathways and cellular responses have been repurposed to facilitate lateral root organogenesis.
植物的根系是成功适应不同土壤类型和环境的关键部分。侧根的形成是决定植物根系形态的主要因素之一，它可以使根系扩展。拟南芥因其简单的根系解剖结构而被广泛研究，以揭示根系分枝的遗传程序。然而，为了更全面地了解侧根的发育，需要在具有更复杂根系解剖结构的物种中进行比较研究。在这里，我们通过结合优化的透明化方法和组织学技术，描述了野生温带草本科植物短柄草侧根发育的图谱。我们发现侧根从增大的韧皮部中柱鞘细胞起始，并且上方的内皮层重新激活其细胞周期，最终形成根冠。此外，DR5 报告基因检测到的生长素信号并未在韧皮部中柱鞘细胞或幼根原基中检测到。相反，生长素信号在上方的皮层细胞层中被激活，包括外皮层。因此，短柄草是一个有价值的模型，可以研究信号通路和细胞反应如何被重新利用来促进侧根器官发生。
