Laboratory of Biochemistry, Wageningen University, Wageningen, 6703HA, the Netherlands.
Physiol Plant. 2014 Jun;151(2):126-33. doi: 10.1111/ppl.12091. Epub 2013 Oct 3.
The first vascular tissue precursors are specified early during embryogenesis. These precursors give rise to the multi-layered cylinder of hypocotyl and root through controlled, oriented divisions. Concomitant with its growth, the bundle is patterned into xylem and phloem tissues, and intervening procambial cells. These patterns are later maintained during post-embryonic growth and vascular cells will eventually differentiate, displaying characteristic secondary cell wall modifications. Given that the vascular system forms de novo in a simple yet predictable fashion, the embryo provides an excellent model system to study early developmental aspects of vascular tissue formation. However, the benefits of this model are only beginning to be exploited, and most knowledge about the vascular development is derived from growing post-embryonic tissues. Importantly, it is unclear how much of these established post-embryonic mechanisms can be extrapolated to tissue formation during embryogenesis. Here we review concepts established in the model plant Arabidopsis thaliana and focus on recent advances made in understanding embryonic vascular development.
最初的血管组织前体在胚胎发生早期被指定。这些前体通过受控的定向分裂，产生出多层的子叶和根的圆柱体。随着其生长，束被模式化为木质部和韧皮部组织以及中间的原形成层细胞。这些模式在胚胎后生长过程中得以维持，并且血管细胞最终会分化，显示出特征性的次生细胞壁修饰。鉴于血管系统以简单但可预测的方式从头形成，胚胎提供了一个极好的模型系统来研究血管组织形成的早期发育方面。然而，这种模型的优势才刚刚开始被利用，并且大多数关于血管发育的知识都来自于生长的胚胎后组织。重要的是，目前尚不清楚这些已建立的胚胎后机制有多少可以外推到胚胎发生过程中的组织形成。在这里，我们回顾了在模式植物拟南芥中建立的概念，并重点介绍了在理解胚胎血管发育方面取得的最新进展。
