冬枣果实韧皮部及其周围薄壁细胞的超微结构观察和功能分析

Ultrastructures of phloem and its surrounding parenchyma cells in the developing Zizyphus jujuba Mill.cv Dongzao fruit

利用透射电镜技术,对发育过程中的冬枣果实韧皮部及周围薄壁细胞的超微结构进行了观察研究。结果表明,果实发育早期筛管伴胞复合体与周围薄壁细胞之间存在少量胞间连丝,发育中期胞间连丝数量有所增加,筛分子和伴胞间及韧皮薄壁细胞间存在丰富的胞间连丝,显示了从筛管伴胞复合体卸出到周围薄壁细胞的同化物的卸载路径可能发生了变化。果实发育的各个时期伴胞胞质致密,富含线粒体、内质网和高尔基体,液泡化程度不等;果实发育前期,筛分子伴胞复合体与邻近的薄壁细胞质膜存在囊泡结构,果实韧皮部薄壁细胞胞质中含有丰富的线粒体、内质网、高尔基体、多泡体和小囊泡,到后期线粒体开始降解,显示了伴随果实发育薄壁细胞内的物质代谢和运转功能经历了由活跃到下降的过程。

The uhrastructures of phloem and its surrounding parenchyma cells in jujube （Zizyphus jujuba Mill. ev Dongzao） fruit were systematically investigated using transmission electron microscopy during the whole developmental process of fruit. The results showed that only a few plasmodesmata （PD） existed between the SE/ CC complex and its surrounding phloem parenchyma cells at the early and late stage of jujube fruit development, while the number of PD increased at the middle stage, suggesting a possible shift of the phloem unloading pathway of photoassimilates in the developmental jujube fruit. The companion ceils contained plenty of organelles such as mitochondria, endoplasmic reticulum, and golgi apparatus. Plenty of vesicles were found between SE/CC complex and its surrounding phloem parenchyma cells at the early stage. There were also abundant organelle in phloem parenchyma cells including mitochondria, endoplasmic reticulum, golgi apparatus, and vesicles which began to dissolve at the late stage, suggesting that metabolism and transport capacity changed in phloem parenchyma ceils with the fruit development.