Institute of Plant Sciences, University of Bern, Bern, Switzerland.
Université Clermont Auvergne, INRA, PIAF, Clermont-Ferrand, France.
PLoS Comput Biol. 2019 Apr 18;15(4):e1006896. doi: 10.1371/journal.pcbi.1006896. eCollection 2019 Apr.
Polar auxin transport lies at the core of many self-organizing phenomena sustaining continuous plant organogenesis. In angiosperms, the shoot apical meristem is a potentially unique system in which the two main modes of auxin-driven patterning-convergence and canalization-co-occur in a coordinated manner and in a fully three-dimensional geometry. In the epidermal layer, convergence points form, from which auxin is canalized towards inner tissue. Each of these two patterning processes has been extensively investigated separately, but the integration of both in the shoot apical meristem remains poorly understood. We present here a first attempt of a three-dimensional model of auxin-driven patterning during phyllotaxis. We base our simulations on a biochemically plausible mechanism of auxin transport proposed by Cieslak et al. (2015) which generates both convergence and canalization patterns. We are able to reproduce most of the dynamics of PIN1 polarization in the meristem, and we explore how the epidermal and inner cell layers act in concert during phyllotaxis. In addition, we discuss the mechanism by which initiating veins connect to the already existing vascular system.
极性生长素运输是许多维持植物连续器官发生的自组织现象的核心。在被子植物中，茎尖分生组织是一个潜在的独特系统，其中生长素驱动的两种主要模式——汇聚和导化——以协调的方式和完全的三维几何结构共同发生。在表皮层中，汇聚点形成，生长素从这些汇聚点被导化到内部组织。这两种模式形成过程中的每一个都已经被广泛研究，但在茎尖分生组织中两者的整合仍然知之甚少。我们在这里首次尝试建立一个三维的叶序发生过程中生长素驱动的模式形成模型。我们的模拟基于 Cieslak 等人提出的一个具有生物化学意义的生长素运输机制（2015），该机制产生了汇聚和导化模式。我们能够重现分生组织中 PIN1 极化的大部分动力学，并且我们探索了表皮层和内层细胞层在叶序发生过程中是如何协同作用的。此外，我们还讨论了起始叶脉与已有的脉管系统连接的机制。
