Schrader Jarmo, Nilsson Jeanette, Mellerowicz Ewa, Berglund Anders, Nilsson Peter, Hertzberg Magnus, Sandberg Göran
Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, 90183 Umeå, Sweden.
Plant Cell. 2004 Sep;16(9):2278-92. doi: 10.1105/tpc.104.024190. Epub 2004 Aug 17.
Plant growth is the result of cell proliferation in meristems, which requires a careful balance between the formation of new tissue and the maintenance of a set of undifferentiated stem cells. Recent studies have provided important information on several genetic networks responsible for stem cell maintenance and regulation of cell differentiation in the apical meristems of shoots and roots. Nothing, however, is known about the regulatory networks in secondary meristems like the vascular cambium of trees. We have made use of the large size and highly regular layered organization of the cambial meristem to create a high-resolution transcriptional map covering 220 microm of the cambial region of aspen (Populus tremula). Clusters of differentially expressed genes revealed substantial differences in the transcriptomes of the six anatomically homogenous cell layers in the meristem zone. Based on transcriptional and anatomical data, we present a model for the position of the stem cells and the proliferating mother cells in the cambial zone. We also provide sets of marker genes for different stages of xylem and phloem differentiation and identify potential regulators of cambial meristem activity. Interestingly, analysis of known regulators of apical meristem development indicates substantial similarity in regulatory networks between primary and secondary meristems.
植物生长是分生组织中细胞增殖的结果，这需要在新组织形成与维持一组未分化干细胞之间保持精细的平衡。最近的研究提供了关于几个负责茎尖和根尖分生组织中干细胞维持及细胞分化调控的基因网络的重要信息。然而，对于像树木维管形成层这样的次生分生组织中的调控网络却一无所知。我们利用形成层分生组织的大尺寸和高度规则的分层结构，创建了一个覆盖杨树（欧洲山杨）形成层区域220微米的高分辨率转录图谱。差异表达基因簇揭示了分生组织区域六个解剖学上同质细胞层转录组的显著差异。基于转录和解剖数据，我们提出了一个关于形成层区域干细胞和增殖母细胞位置的模型。我们还提供了木质部和韧皮部分化不同阶段的标记基因集，并鉴定了形成层分生组织活性的潜在调节因子。有趣的是，对已知顶端分生组织发育调节因子的分析表明，初生和次生分生组织的调控网络存在显著相似性。
