The development of secondary vascular tissue enhances the transport capacity and mechanical strength of plant bodies, while contributing a huge proportion of the world’s biomass in the form of wood. Cell divisions in the cambium, which constitutes the vascular meristem, provide progenitors from which conductive xylem and phloem are derived. The cambium is a somewhat unusual stem cell population in two respects, making it an interesting subject for developmental research. Firstly, it arises post-germination, and thus represents a model for understanding stem cell initiation beyond embryogenesis. Secondly, xylem and phloem differentiate on opposing sides of cambial stem cells, making them bifacial in nature. Recent discoveries in Arabidopsis thaliana have provided insight into the molecular mechanisms that regulate the initiation, patterning, and maintenance of the cambium. In this review, the roles of intercellular signalling via mobile transcription factors, peptide–receptor modules, and phytohormones are described. Crosstalk between these regulatory pathways is becoming increasingly apparent, yet the underlying mechanisms are not fully understood. Future study of the interaction between multiple independently identified regulators, as well as the functions of their orthologues in trees, will deepen our understanding of radial growth in plants.

中文翻译：

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厚涂：二次生长研究

次生维管组织的发育增强了植物体的运输能力和机械强度，同时以木材的形式贡献了世界生物质的巨大比例。形成维管分生组织的形成层中的细胞分裂提供了祖细胞，传导性木质部和韧皮部由这些祖细胞衍生。形成层在两个方面是一个有点不寻常的干细胞群，使其成为发展研究的一个有趣主题。首先，它出现在发芽后，因此代表了理解胚胎发生之外的干细胞起始的模型。其次，木质部和韧皮部在形成层干细胞的相对两侧分化，使它们本质上是双面的。最近在拟南芥中的发现提供了对调节起始、模式、和形成层的维护。在这篇综述中，描述了通过移动转录因子、肽受体模块和植物激素的细胞间信号传导的作用。这些调节途径之间的串扰变得越来越明显，但其潜在机制尚不完全清楚。未来对多个独立确定的调节因子之间的相互作用以及它们在树木中的直系同源物功能的研究将加深我们对植物径向生长的理解。