Durand Caroline, Vicré-Gibouin Maïté, Follet-Gueye Marie Laure, Duponchel Ludovic, Moreau Myriam, Lerouge Patrice, Driouich Azeddine
Laboratoire de Glycobiologie et Matrice Extracellulaire Végétale, Unité Propre de Recherche et d'Enseignement Supérieur Associé 4358, Institut Fédératif de Recherche Multidisciplinaire sur les Peptides 23, Plate-Forme de Recherche en Imagerie Cellulaire de Haute Normandie, Université de Rouen, 76821 Mont Saint Aignan, France.
Plant Physiol. 2009 Jul;150(3):1411-21. doi: 10.1104/pp.109.136382. Epub 2009 May 15.
Border-like cells are released by Arabidopsis (Arabidopsis thaliana) root tips as organized layers of several cells that remain attached to each other rather than completely detached from each other, as is usually observed in border cells of many species. Unlike border cells, cell attachment between border-like cells is maintained after their release into the external environment. To investigate the role of cell wall polysaccharides in the attachment and organization of border-like cells, we have examined their release in several well-characterized mutants defective in the biosynthesis of xyloglucan, cellulose, or pectin. Our data show that among all mutants examined, only quasimodo mutants (qua1-1 and qua2-1), which have been characterized as producing less homogalacturonan, had an altered border-like cell phenotype as compared with the wild type. Border-like cells in both lines were released as isolated cells separated from each other, with the phenotype being much more pronounced in qua1-1 than in qua2-1. Further analysis of border-like cells in the qua1-1 mutant using immunocytochemistry and a set of anti-cell wall polysaccharide antibodies showed that the loss of the wild-type phenotype was accompanied by (1) a reduction in homogalacturonan-JIM5 epitope in the cell wall of border-like cells, confirmed by Fourier transform infrared microspectrometry, and (2) the secretion of an abundant mucilage that is enriched in xylogalacturonan and arabinogalactan-protein epitopes, in which the cells are trapped in the vicinity of the root tip.
拟边缘细胞由拟南芥（Arabidopsis thaliana）根尖释放，形成几层细胞组成的有序层，这些细胞彼此保持附着，而不像许多物种的边缘细胞那样完全相互分离。与边缘细胞不同，拟边缘细胞释放到外部环境后，细胞间的附着得以维持。为了研究细胞壁多糖在拟边缘细胞附着和组织中的作用，我们检测了它们在几种木葡聚糖、纤维素或果胶生物合成缺陷的典型突变体中的释放情况。我们的数据表明，在所有检测的突变体中，只有拟态突变体（qua1-1和qua2-1）表现出与野生型相比改变的拟边缘细胞表型，这两个突变体已被鉴定为产生较少的同型半乳糖醛酸聚糖。这两个株系中的拟边缘细胞均以彼此分离的单个细胞形式释放，qua1-1中的表型比qua2-1中更为明显。使用免疫细胞化学和一组抗细胞壁多糖抗体对qua1-1突变体中的拟边缘细胞进行进一步分析表明，野生型表型的丧失伴随着：（1）傅里叶变换红外光谱法证实，拟边缘细胞细胞壁中同型半乳糖醛酸聚糖-JIM5表位减少；（2）分泌大量富含木糖半乳糖醛酸聚糖和阿拉伯半乳聚糖蛋白表位的黏液，细胞被困在根尖附近。
