Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Prague 6, Czech Republic.
Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague 2, Czech Republic.
J Exp Bot. 2019 Feb 20;70(4):1255-1265. doi: 10.1093/jxb/erz005.
The collet (root-hypocotyl junction) region is an important plant transition zone between soil and atmospheric environments. Despite its crucial importance for plant development, little is known about how this transition zone is specified. Here we document the involvement of the exocyst complex in this process. The exocyst, an octameric tethering complex, participates in secretion and membrane recycling and is central to numerous cellular and developmental processes, such as growth of root hairs, cell expansion, recycling of PIN auxin efflux carriers and many others. We show that dark-grown Arabidopsis mutants deficient in exocyst subunits can form a hair-bearing ectopic collet-like structure above the true collet, morphologically resembling the true collet but also retaining some characteristics of the hypocotyl. The penetrance of this phenotypic defect is significantly influenced by cultivation temperature and carbon source, and is related to a defect in auxin regulation. These observations provide new insights into the regulation of collet region formation and developmental plasticity of the hypocotyl.
合生组织（根-下胚轴交界处）是植物在土壤和大气环境之间的一个重要过渡区。尽管这个过渡区对植物的发育非常重要，但对于这个过渡区是如何被指定的，人们知之甚少。在这里，我们记录了外被体复合物在这个过程中的参与。外被体是一个八聚体的 tethering 复合物，参与分泌和膜循环，是许多细胞和发育过程的核心，如根毛的生长、细胞的扩张、PIN 生长素外排载体的再循环等等。我们发现，黑暗中生长的拟南芥突变体缺乏外被体亚基，会在真正的合生组织上方形成一个具有毛的合生组织样结构，形态上类似于真正的合生组织，但也保留了下胚轴的一些特征。这种表型缺陷的出现率受到培养温度和碳源的显著影响，与生长素调节的缺陷有关。这些观察结果为合生组织区域形成和下胚轴发育可塑性的调控提供了新的见解。
