Shevell D E, Kunkel T, Chua N H
Laboratory of Plant Molecular Biology, The Rockefeller University, New York, New York 10021, USA.
Plant Cell. 2000 Nov;12(11):2047-60. doi: 10.1105/tpc.12.11.2047.
The Arabidopsis EMB30 gene is essential for controlling the polarity of cell growth and for normal cell adhesion during seedling development. In this article, we show that emb30 mutations also affect the growth of undifferentiated plant cells and adult tissues. EMB30 possesses a Sec7 domain and, based on similarities to other proteins, presumably functions in the secretory pathway. The plant cell wall depends on the secretory pathway to deliver its complex polysaccharides. We show that emb30 mutants have a cell wall defect that sometimes allows material to be deposited into the interstitial space between cells instead of being restricted to cell corners. In addition, pectin, a complex polysaccharide important for cell adhesion, appears to be abnormally localized in emb30 plants. In contrast, localization of epitopes associated with xyloglucan or arabinogalactan was similar in wild-type and emb30 tissues, and the localization of a marker molecule to vacuoles appeared normal. Therefore, emb30 mutations do not cause a general defect in the secretory pathway. Together, these results suggest that emb30 mutations result in an abnormal cell wall, which in turn may account for the defects in cell adhesion and polar cell growth control observed in the mutants.
拟南芥EMB30基因对于控制细胞生长极性以及幼苗发育过程中的正常细胞黏附至关重要。在本文中，我们表明emb30突变也会影响未分化植物细胞和成熟组织的生长。EMB30具有一个Sec7结构域，基于与其他蛋白质的相似性，推测其在分泌途径中发挥作用。植物细胞壁依赖于分泌途径来输送其复合多糖。我们发现emb30突变体存在细胞壁缺陷，有时会使物质沉积到细胞间的间隙中，而不是局限于细胞角隅。此外，果胶是一种对细胞黏附很重要的复合多糖，在emb30植株中其定位似乎异常。相比之下，与木葡聚糖或阿拉伯半乳聚糖相关的表位在野生型和emb30组织中的定位相似，并且一种标记分子在液泡中的定位看起来正常。因此，emb30突变不会导致分泌途径出现普遍缺陷。综合这些结果表明，emb30突变导致细胞壁异常，这反过来可能解释了在突变体中观察到的细胞黏附和极性细胞生长控制方面的缺陷。
