Abstract:

The development, cytological characters and ultrastructure of phloem ganglion in the nodal region of Phyllostachys edulis (Carr.) H. de Lehaie, a most economically important bamboo, were investigated and the possible physiological function of this special structure was proposed. The phloem ganglion derived directly from procambium is situated at the sites where the vascular bundle forks and is present in pairs. The phloem ganglion is spindle-like in appearance and usually consists of 4 to 6 layers. Two kinds of cells in the ganglion could be distinguished. In the middle, there are two layers of filiform cells with pointed ends so that there are no normal sieve plates. Nevertheless, there are many pits on the lateral wall of the filiform cells. The other type of cells located at both ends of the spindle which possess an intermediate form between the filiform cell and the normal sieve tube. The walls of these cells towards the filiform cells are strongly convex forming a special sieve plate. Ultrastructure study showed that cells in the ganglion are connected by enriched plasmodesma. During early differentiation, the paramural body and the ingrowth of cell wall could be observed. It indicates that the cells of phloem ganglion have the character of transfer cells. The organelles in the mature cells are mainly plastids with abundant accumulation of proteins of crystalline structure. The above-mentioned results suggest that the physiological function of the phloem ganglion is closely related with substance transport. 

竹子节部“韧皮部结”的发育与超微结构
丁雨龙* 樊汝汶 黄金生
（南京林业大学森林资源与环境学院，南京210037）

摘要：研究了中国最为重要的经济竹种毛竹 (Phyllostachysedulis (Carr.)H .deLehaie)节部“韧皮部结”的个体发育、构成该结构细胞的形态学特征及其超微结构 ,探讨了该结构可能的生理功能。“韧皮部结”的发育直接来源于原形成层 ,发生在维管束分叉处 ,一般成对出现。“韧皮部结”外形呈纺锤体状 ,一般由 4～ 6层细胞形成叠生构造。构成“韧皮部结”的细胞可以区分为两类 ,一类是位于纺锤体中部的两层细胞 ,呈线条形 ,两端尾尖 ,因而无筛板 ,但在侧壁上有大量的纹孔 ;另一类是位于纺锤体两端、形态介于线条形细胞和正常筛管分子之间的细胞 ,此类细胞两端的端壁形态不同。与线条形细胞相连接的一端明显隆起 ,形成特殊形态的筛板。超微结构研究表明 ,构成“韧皮部结”的细胞之间胞间连丝十分丰富 ,细胞壁具有内突 ,因而具有传递细胞的特征。成熟细胞内的细胞器以富含蛋白质的质体为主。“韧皮部结”的功能 ,根据其发生的部位 ,显然与物质的分流密切相关。

关键词： 韧皮部结；个体发育；超微结构；生理功能

Key words: phloem ganglion, individual development, ultrastructure, physiological function