Cell wall differentiation during early somatic embryogenesis in plants. II. Ultrastructural study and pectin immunolocalization on chicory embryos
Cell wall differentiation during early somatic embryogenesis in plants. II. Ultrastructural study and pectin immunolocalization on chicory embryos
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DOI：
10.1139/cjb-78-6-824
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发表时间：
2000-06-01
期刊：
影响因子：
--
通讯作者：
Hilbert, JL
中科院分区：
文献类型：
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作者：
Chapman, A;Blervacq, AS;Hilbert, JL
在菊苣474（C. intybus L.变种sativum x C. [医]山毛榉属变种latifolia），从根诱导直接体细胞胚发生。利用透射电镜观察了胚胎发育过程中细胞外壁超微结构的变化。在胚性细胞向体细胞胚转化的过程中，细胞壁的分化过程包括沉积和重排两个过程。在第一次分裂期间，仍然封闭在根组织中的少细胞胚的细胞壁呈现为大的无定形纤维素层，比根皮层细胞的细胞壁厚。当原胚出现的根细胞，外壁表面表现出纤维状的材料指定为胚上网络。随着这个网络的消失，细胞壁的外部组织发生了变化，并区分出两个域。鱼雷期，细胞外壁致密，无间隙，原皮层分化。由JIM5抗体识别的表位的免疫定位揭示了胚上网络的未酯化性质。这种果胶也位于外三分之一的外原皮层细胞的细胞壁以及在细胞间隙。在胚胎发生过程中，由JIM7抗体识别的高度甲基化的果胶略微存在于细胞壁中。外细胞壁分化的不同阶段，以及瞬态超胚网络的发展进行了描述，并提出其在体细胞胚胎发生的可能作用。
In Cichorium hybrid clone 474 (C. intybus L. var. sativum x C. endivia L. var. latifolia), direct somatic embryogenesis was induced from roots. Using transmission electron microscopy, we followed the ultrastructural changes of the outer cell wall in relation to embryo developmental stage. During the transition from an embryogenic cell to a somatic embryo, the differentiation of the outer cell wall involved both deposition and rearrangement processes. During the first divisions, the cell wall of few-celled embryos still enclosed in the root tissue appeared as a large amorphous layer of cellulose, thicker than the cell walls of the root cortex cells. When the proembryo emerged from the root cells, the outer wall surface exhibited a fibrillar material designated as the supraembryonic network. As this network disappeared, the outer cell wall changed organization, and two domains were distinguished. At the torpedo stage, the outer cell wall was more compact without any gaps and the protoderm was differentiated. Immunolocalization of an epitope recognised by JIM5 antibody revealed the unesterified nature of the supraembryonic network. Such pectins were also located at the outer third of the outer cell wall of protodermal cells as well as in the intercellular spaces. Highly methylesterified pectins recognized by JIM7 antibodies were slightly present in the cell walls during the embryogenesis process. The different stages of the outer cell wall differentiation as well as the development of the transient supraembryonic network are described, and its possible roles in somatic embryogenesis are proposed.