A weed for wood? Arabidopsis as a genetic model for xylem development
A weed for wood? Arabidopsis as a genetic model for xylem development
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DOI：
10.1104/pp.104.040212
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发表时间：
2004-06-01
期刊：
影响因子：
7.4
通讯作者：
Helariutta, Y
中科院分区：
文献类型：
--
作者：
Nieminen, KM;Kauppinen, L;Helariutta, Y
木材，或次生木质部，是具有高度树木特征的导水和支持维管组织。除了具有储存和运输功能的薄壁细胞外，木材主要由各种垂直伸长的细胞类型组成。它们可分为管状细胞或纤维，两者都具有广泛的次生细胞壁增厚的特征。细胞壁的特性有助于木材的特性，作为各种人类应用的重要原材料。木材的形成发生在植物发育的第二阶段（图1）。这是由于维管形成层的活动，这是一种在次生期建立并起作用的侧分生组织。另一方面，维管发育的初级阶段，与顶端分生组织的原形成层发育有关，涉及木质部的产生。初生木质部和次生木质部的形成涉及一系列有趣的过程，包括初生维管束组织的规范、初生维管束或次生维管束形成层内的细胞增殖、木质部分化的开始、细胞膨胀的调节、次生细胞壁的沉积和程序性细胞死亡（图1）。尽管这些过程在结构层面上被广泛记录，但对其背后的遗传机制却知之甚少。虽然木材形成是树木的一个明显特征，但许多草本植物，包括拟南芥，也发育维管形成层并形成次生木质部。因此，拟南芥可以被认为是木质部在初级和次级发育阶段的发育过程的模型。在本文中，我们将首先回顾与木质部形成相关的每个发育过程的最新研究成果，最后将重点放在次生发育阶段，根据最新的分子数据比较拟南芥和树木的木材发育。
Wood, or secondary xylem, is a water-conductive and supportive vascular tissue highly characteristic of trees. In addition to parenchymatous cells adapted for storage and transport functions, wood is mainly composed of various vertically elongated cell types. These are classified either as tracheary elements or fibers, both of which are characterized with extensive secondary cell wall thickenings. The cell wall characteristics contribute to the properties of wood as a significant raw material for various human applications.Wood formation occurs during the secondary phase of plant development (Fig. 1). This results from the activity of the vascular cambium, a lateral meristem that is established and functional during the secondary phase. On the other hand, already the primary phase of vascular development, associated with the procambial development of apical meristems, involves xylem production. The formation of both primary and secondary xylem involves a cascade of interesting processes including specification of primary vascular tissue as bundles, cell proliferation within the primary bundles or in the secondary vascular cambium, initiation of xylem differentiation, regulation of cell expansion, deposition of a secondary cell wall, and programmed cell death (Fig. 1). Even as these processes have been extensively documented at the structural level, relatively little is known of the genetic mechanisms behind them. Although wood formation is an evident characteristic of trees, also many herbaceous plants, including Arabidopsis, develop vascular cambium and form secondary xylem. Thus, Arabidopsis can be considered as a model for the developmental processes underlying xylem development during both primary and secondary phases of development. In this Update we will first review the most recent work related to each developmental process resulting in xylem formation and finally focus on the secondary phase of development to compare wood development in Arabidopsis and trees in light of the most recent molecular data.