Le Bail Aude, Billoud Bernard, Maisonneuve Carole, Charrier Bénédicte
UMR7139, Station Biologique, Centre National de la Recherche Scientifique, Université Pierre & Marie Curie, Place Georges Teissier, 29682 Roscoff cedex, France.
J Soc Biol. 2007;201(3):267-80. doi: 10.1051/jbio:2007038.
In response to environmental constraints, living organisms organise their body according to axes, rotation and translation plans, or asymmetries. Cellular and molecular processes are involved in the establishment of this architecture. Hence, this review aims at presenting the molecular mechanisms controlling the main symmetries and axes in plants. Several genes, coding for transcription factors, have been identified in land plants (mainly Arabidopsis thaliana), as controlling the establishment of apico-basal and adaxial-abaxial axes mainly. The establishment of these axes allows the development in other spatial directions of radial or bilateral symmetries. These processes seem in most cases to be under the control of the phytohormone auxin. In brown algae, which are all multicellular marine plants, polarity plans are less obvious than in land plants. The development of the model brown alga Ectocarpus siliculosus is currently being studied. E. siliculosus develops a filamentous architecture, and primary observations show that branching along the main axis occurs in a non-stereotyped and regular way, even though it is mainly centred. However, more detailed morphometrical studies, accompanied by probabilistic analyses, have shown that, among the overall population of individuals, organisms obey yet unidentified biological constraints, that aim at refining the radial symmetry as the organism grows. The role of this symmetry in the adaptation of E. siliculosus to its environment, as well as the molecular actors involved in this process, are currently under study in our laboratory.
为响应环境限制，生物体根据轴、旋转和平移计划或不对称性来组织其身体。细胞和分子过程参与了这种结构的建立。因此，本综述旨在介绍控制植物主要对称性和轴的分子机制。在陆地植物（主要是拟南芥）中，已经鉴定出几个编码转录因子的基因，主要控制顶 - 基轴和近轴 - 远轴的建立。这些轴的建立允许在径向或双侧对称的其他空间方向上发育。在大多数情况下，这些过程似乎受植物激素生长素的控制。在所有多细胞海洋植物的褐藻中，极性模式不如陆地植物明显。目前正在研究模式褐藻硅藻的发育。硅藻形成丝状结构，初步观察表明，尽管主要集中在主轴上，但沿主轴的分支以非定型但规则的方式发生。然而，更详细的形态计量学研究以及概率分析表明，在个体的总体种群中，生物体遵循尚未确定的生物学限制，这些限制旨在随着生物体的生长完善径向对称性。这种对称性在硅藻适应其环境中的作用以及参与该过程的分子因素，目前正在我们实验室进行研究。
