Abstract:

The ultrastructure of the epidermis and flesh of apple (Malus domestica Borkh cv. Red Fuji) fruit was systematically observed during the fruit development via transmission electron microscopy. The results showed that, in spite of the ultrastructural changes in many aspects of the developing fruit epidermal cells, it remained almost unchanged throughout the whole developmental process that the cytoplasm was filled with numerous endoplasmic reticula (ER). Most of these endoplasmic reticula were tube-like and rough-ER with enlarged cisterna from which many vesicles were produced. Some of the vesicles were shown to merge into vacuole. Some dynamic Golgi bodies were also found. All the ultrastructural characteristics showed that the epidermal cells have the features of excretory cells. The ultrastructure of the fruit flesh cells at the young fruit stage were shown to be metabolically active, characterized by the presence of numerous clustered plasmodesmata, cisterna enlarged- and rough-ER filling the cytoplasm, plenty of vesicles and Golgi bodies, indicating their dynamic cellular transport function. Some giant-circular rough-ERs were found. All the ultrastructural features at this early developmental stage should be closely associated with the enlargement of the young fruit. At the rapid growing phase of the fruit the main changes were characterized by: the starch grain-filled amyloplasts, furcating of the single orifice of plasmodesmata, and the cytoplasm enrichment of both the Golgi body-formed vesicles and other vesicles. These features correspond well with those of a photoassimilate sink-cell. An ultrastructural degeneration phenomenon was observed at the fruit ripening stage, but the mitochondria and plasmalemma still remained intact, which might be related to the continuous development of fruit quality during the fruit ripening.

发育过程中苹果果皮和果肉细胞的超微结构
彭宜本* 张大鹏**

（中国农业大学果树分子发育生物学实验室，北京100094）

摘要：用透射电镜对发育过程中苹果 (Malusdomestica Borkhcv.RedFuji)果皮和果肉细胞的超微结构进行了观察。结果表明 ,不同发育期果皮细胞的超微结构发生了变化 ,其中最引人注目的是 ,内质网自始至终密布于整个细胞质中 ,而且大多为槽库膨大的、合成功能旺盛的管状粗面内质网 ,并分泌出大量的具运输功能的小泡 ;观察到这些小泡与液泡融合的景象 ;细胞中也存在活跃的高尔基体。超微结构上的这些现象显示了果皮细胞具有分泌细胞的基本特征。果肉细胞在幼果生长期表现出代谢旺盛的特点 ;观察到成束出现的胞间连丝、遍布于整个细胞质中的槽库膨大的粗面内质网、丰富的大小囊泡和活跃的高尔基体 ;也观察到巨大的环型粗面内质网。在果实快速生长期 ,整个造粉质体内充满淀粉 ,胞间连丝由幼果期的单通道发育为分叉型通道 ,细胞质中存在丰富的囊泡和活跃地分泌小泡的高尔基体。在果实成熟期 ,果肉细胞呈现出降解的特点 ,线粒体仍然完好 ,质膜依然完整。对果皮和果肉细胞超微结构变化与果实发育的关系进行了讨论。

关键词： 苹果；果实；果皮；果肉；超微结构；果实发育
 

Key words: apple, fruit, epidermis, flesh, ultrastructure, fruit development