灵武长枣果实维管束韧皮部及周围细胞的超微结构特征

Ultrastructural characteristics of Ziziphus jujuba cv. Lingwuchangzao fruit vascular bundles phloem and its surrounding parenchyma cells

关键词:  灵武长枣, 果实, SE/CC复合体, 薄壁细胞, 超微结构

Key words:   Ziziphus jujuba cv. Lingwuchangzao, fruit, SE/CC complex, parenchyma cell, ultrastructure

摘要:

为了探讨灵武长枣果实光合同化物韧皮部卸载和运输的途径,该研究采用透射电镜技术,对不同发育时期灵武长枣果实维管束韧皮部及其周围薄壁细胞的超微结构特征进行了分析。结果表明:筛管/伴胞复合体及其周围韧皮薄壁细胞间在果实膨大前期富含胞间连丝,而韧皮薄壁细胞与周围库细胞以及相邻库细胞间几乎不存在胞间连丝,形成共质体隔离; 筛管/伴胞复合体及其与周围薄壁细胞间在果实快速膨大期也存在胞间连丝,但与果实膨大前期相比明显减少; 果实着色期,SE/CC复合体及其与周围薄壁细胞间胞间连丝较少,并且出现阻塞现象; 果实完熟期,筛管和伴胞之间几乎没有胞间连丝,有的筛管之间有少量胞间连丝,但却出现了阻塞现象,果肉库薄壁细胞与韧皮薄壁细胞间因胞间连丝阻塞现象而形成共质体隔离。综上结果认为,在果实发育的膨大前期阶段,光合同化物以共质体途径经筛分子卸出,卸出后可能以质外体途径进入液泡贮藏与利用; 果实快速膨大期,光合同化物的卸出与运输采用共质体和质外体共存的途径; 果实着色期和完熟期,光合同化物从筛分子卸出到贮藏薄壁细胞的运输均以质外体途径为主。

Abstract:

By using transmission electron microscopy, the ultrastructures of different developmental stages Ziziphus jujuba cv. Lingwuchangzao fruit vascular bundles phloem and its surrounding parenchyma cells were analysed to discover the phloem unloading and transport pathway of photoassimilates. The results were as follows: SE/CC complex and its surrounding phloem parenchyma cells between riched plasmodesmata, and phloem parenchyma cells and surrounding cells and adjacent flesh parenchyma cells were almost non-existent plasmodesmata and formed symplastic isolation in the early bulking period; In the rapid enlargement period, plasmodesmata were found between SE/CC complex and the surrounding parenchyma cells, but the number significantly reduced compared with the early bulking period; In the coloring period, SE/CC complex and its surrounding parenchyma cells had less plasmodesmatas and appeared blockade phenomenon; In the maturation period, there were not almost plasmodesmata between sieve tube elements and companion cells, some sieve tube elements had less plasmodesmatas but appeared blockade phenomena, flesh parenchyma cells and phloem parenchyma cells formed symplastic isolation because of plasmodesmatas blockade phenomena. Therefore, the unloading of photoassimilates from sieve tube element was symplast pathway and adopted apoplastic pathway after unloading into vacuole storage and utilization in the early bulking period, the unloading transportant of photoassimilates took the symplast and apoplastic concomitant pathway in the rapid enlargement period, transportation of photoassimilates from sieve tube element to storage parenchyma cells was based on apoplastic pathway in the coloring period and the maturation period fruit.