Entwicklungsbiologie der Pflanzen, Wissenschaftszentrum Weihenstephan, Technische Universität München, Emil-Ramann-Strasse 4, 85354, Freising, Germany.
Protoplasma. 2013 Jun;250(3):651-61. doi: 10.1007/s00709-012-0452-0. Epub 2012 Sep 16.
Tissue morphogenesis requires extensive intercellular communication. Plant organs are composites of distinct radial cell layers. A typical layer, such as the epidermis, is propagated by stereotypic anticlinal cell divisions. It is presently unclear what mechanisms coordinate cell divisions relative to the plane of a layer, resulting in planar growth and maintenance of the layer structure. Failure in the regulation of coordinated growth across a tissue may result in spatially restricted abnormal growth and the formation of a tumor-like protrusion. Therefore, one way to approach planar growth control is to look for genetic mutants that exhibit localized tumor-like outgrowths. Interestingly, plants appear to have evolved quite robust genetic mechanisms that govern these aspects of tissue morphogenesis. Here we provide a short summary of the current knowledge about the genetics of tumor formation in plants and relate it to the known control of coordinated cell behavior within a tissue layer. We further portray the integuments of Arabidopsis thaliana as an excellent model system to study the regulation of planar growth. The value of examining this process in integuments was established by the recent identification of the Arabidopsis AGC VIII kinase UNICORN as a novel growth suppressor involved in the regulation of planar growth and the inhibition of localized ectopic growth in integuments and other floral organs. An emerging insight is that misregulation of central determinants of adaxial-abaxial tissue polarity can lead to the formation of spatially restricted multicellular outgrowths in several tissues. Thus, there may exist a link between the mechanisms regulating adaxial-abaxial tissue polarity and planar growth in plants.
组织形态发生需要广泛的细胞间通讯。植物器官是由不同的径向细胞层组成的复合材料。一个典型的层，如表皮，是通过典型的垂周细胞分裂来繁殖的。目前尚不清楚是什么机制相对于层的平面来协调细胞分裂，从而导致平面生长和层结构的维持。如果不能协调组织内的生长，可能会导致空间上受限的异常生长和肿瘤样突起的形成。因此，一种研究平面生长控制的方法是寻找表现出局部肿瘤样生长的遗传突变体。有趣的是，植物似乎已经进化出相当强大的遗传机制来控制组织形态发生的这些方面。在这里，我们简要总结了目前关于植物肿瘤形成的遗传学知识，并将其与已知的组织层内协调细胞行为的控制联系起来。我们进一步将拟南芥的表皮作为研究平面生长调控的优秀模型系统来描绘。通过最近鉴定出拟南芥 AGC VIII 激酶 UNICORN 是一种新的生长抑制剂，参与调节表皮和其他花器官中的平面生长和抑制局部异位生长，研究这个过程的价值得到了确立。一个新的认识是，中央决定体的失调可以导致几个组织中空间受限的多细胞生长。因此，在植物中，调节近远轴组织极性的机制与平面生长之间可能存在联系。
