Functional Genomics and Proteomics of Plants, Central European Institute of Technology, Masaryk University, Brno, Czech Republic.
PLoS One. 2013 May 27;8(5):e63108. doi: 10.1371/journal.pone.0063108. Print 2013.
Plant vascular meristems are sets of pluripotent cells that enable radial growth by giving rise to vascular tissues and are therefore crucial to plant development. However, the overall dynamics of cellular determination and patterning in and around vascular meristems is still unexplored. We study this process in the shoot vascular tissue of Arabidopsis thaliana, which is organized in vascular bundles that contain three basic cell types (procambium, xylem and phloem). A set of molecules involved in this process has now been identified and partially characterized, but it is not yet clear how the regulatory interactions among them, in conjunction with cellular communication processes, give rise to the steady patterns that accompany cell-fate determination and arrangement within vascular bundles. We put forward a dynamic model factoring in the interactions between molecules (genes, peptides, mRNA and hormones) that have been reported to be central in this process, as well as the relevant communication mechanisms. When a few proposed interactions (unverified, but based on related data) are postulated, the model reproduces the hormonal and molecular patterns expected for the three regions within vascular bundles. In order to test the model, we simulated mutant and hormone-depleted systems and compared the results with experimentally reported phenotypes. The proposed model provides a formal framework integrating a set of growing experimental data and renders a dynamic account of how the collective action of hormones, genes, and other molecules may result in the specification of the three main cell types within shoot vascular bundles. It also offers a tool to test the necessity and sufficiency of particular interactions and conditions for vascular patterning and yields novel predictions that may be experimentally tested. Finally, this model provides a reference for further studies comparing the overall dynamics of tissue organization and formation by meristems in other plant organs and species.
植物维管形成层是一组多能细胞，通过产生维管组织来实现径向生长，因此对植物的发育至关重要。然而，维管形成层内部和周围的细胞决定和模式形成的整体动态仍然未知。我们在拟南芥的茎维管组织中研究这个过程，茎维管组织由含有三种基本细胞类型（原形成层、木质部和韧皮部）的维管束组成。现在已经确定并部分描述了一组参与这个过程的分子，但还不清楚它们之间的调控相互作用，以及与细胞通讯过程相结合，如何产生伴随维管束内细胞命运决定和排列的稳定模式。我们提出了一个动态模型，该模型考虑了在这个过程中被认为是核心的分子（基因、肽、mRNA 和激素）之间的相互作用，以及相关的通讯机制。当假设一些被提出的相互作用（未经证实，但基于相关数据）时，该模型可以再现维管束内三个区域的激素和分子模式。为了验证该模型，我们模拟了突变体和激素耗尽系统，并将结果与实验报告的表型进行了比较。所提出的模型提供了一个整合了一系列不断增长的实验数据的正式框架，并提供了一个动态的解释，说明激素、基因和其他分子的集体作用如何导致茎维管束内三种主要细胞类型的特化。它还提供了一种工具来测试特定相互作用和条件对于血管模式形成的必要性和充分性，并产生了可能通过实验测试的新预测。最后，这个模型为进一步的研究提供了一个参考，比较了其他植物器官和物种的分生组织中组织组织和形成的整体动态。
