Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology (CEITEC), Masaryk University, Kamenice 5, CZ-625 00 Brno, Czech Republic; Department of Plant Systems Biology, VIB and Department of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 927, 9052 Gent, Belgium.
Department of Plant Systems Biology, VIB and Department of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 927, 9052 Gent, Belgium.
Mol Plant. 2015 Aug;8(8):1175-87. doi: 10.1016/j.molp.2015.03.007. Epub 2015 Mar 17.
The sessile life style of plants creates the need to deal with an often adverse environment, in which water availability can change on a daily basis, challenging the cellular physiology and integrity. Changes in osmotic conditions disrupt the equilibrium of the plasma membrane: hypoosmotic conditions increase and hyperosmotic environment decrease the cell volume. Here, we show that short-term extracellular osmotic treatments are closely followed by a shift in the balance between endocytosis and exocytosis in root meristem cells. Acute hyperosmotic treatments (ionic and nonionic) enhance clathrin-mediated endocytosis simultaneously attenuating exocytosis, whereas hypoosmotic treatments have the opposite effects. In addition to clathrin recruitment to the plasma membrane, components of early endocytic trafficking are essential during hyperosmotic stress responses. Consequently, growth of seedlings defective in elements of clathrin or early endocytic machinery is more sensitive to hyperosmotic treatments. We also found that the endocytotic response to a change of osmotic status in the environment is dominant over the presumably evolutionary more recent regulatory effect of plant hormones, such as auxin. These results imply that osmotic perturbation influences the balance between endocytosis and exocytosis acting through clathrin-mediated endocytosis. We propose that tension on the plasma membrane determines the addition or removal of membranes at the cell surface, thus preserving cell integrity.
植物的固着生活方式使其需要应对经常变化的环境，其中水分的可利用性可能每天都在变化，这对细胞的生理和完整性提出了挑战。渗透条件的变化破坏了质膜的平衡：低渗条件会增加细胞体积，而高渗环境会减少细胞体积。在这里，我们表明，短期的细胞外渗透压处理会紧接着导致根分生组织细胞中内吞作用和胞吐作用之间的平衡发生转移。急性高渗处理（离子和非离子）同时增强网格蛋白介导的内吞作用，同时减弱胞吐作用，而低渗处理则产生相反的效果。除了网格蛋白向质膜募集外，早期内吞作用的成分在高渗应激反应中也是必不可少的。因此，在网格蛋白或早期内吞作用机制元件有缺陷的幼苗中，对高渗处理更为敏感。我们还发现，对环境中渗透压变化的内吞反应在植物激素（如生长素）的调节作用方面占主导地位，而后者可能是进化上更为新近的作用。这些结果表明，渗透压的变化通过网格蛋白介导的内吞作用影响内吞作用和胞吐作用之间的平衡。我们提出，质膜的张力决定了细胞膜在细胞表面的添加或去除，从而保持细胞的完整性。
