摘要
利用常规电镜技术,观察研究了美洲黑杨Populus deltoides次生木质部导管分化过程的超微结构变化。结果表明:美洲黑杨导管形态的建成可划分为初生壁的延展、次生壁的构建与穿孔板的形成等3个时期。初生壁的延展是导管分化的初始阶段,导管细胞高度液泡化,细胞质及其细胞器贴壁分布。次生壁的构建是导管分化的关键阶段,次生壁物质的沉积在导管液泡膜破裂之前即已开始,此时导管分子内细胞器结构清晰,其中高尔基体及其分泌小泡最为丰富,说明高尔基体与次生壁物质的合成及运输密切相关;导管分子液泡膜裂解后,次生壁物质沉积极为迅速,伴随次生壁物质的合成,导管分子细胞质解体,细胞核染色质凝聚并边缘化,表现出程序化细胞死亡(PCD)的典型特征。穿孔板的形成是导管分化的终极阶段,在导管次生壁形成时,相邻导管分子的端壁上不发生壁物质的积累,而且在次生壁构建后期,端壁上的壁物质降解,最后残余的端壁断裂形成穿孔板。美洲黑杨次生木质部导管的分化阶段彼此相继有序地进行,其中次生壁构建的启动是导管分子不可逆分化的临界期,随后的分化阶段是一种典型的PCD过程。
Using electronic microscopy, ultrastructural changes were observed during differentiation in a secondary xylem vessel element （VE） of Populus deltoides. Results showed that morphological development of VE differentiation was successively divided into three stages. First was prolongation of the primary cell wall （the initial stage）, where the VE was highly vacuolated and the protoplasm was distributed along the cell wall. Second was establishment of the secondary cell wall （the pivotal stage） where substances accumulated before the tonoplast broke, and VE organelle structure was distinct. Colgi bodies and vesicles, which were associated closely with synthesis and transportation of secondary cell wall substances, were also abundant. After the tonoplast broke, these substances accumulated faster. Simultaneously, the protoplasm disaggregated, and the agglomerate chromatin was distributed over the. margin of the nucleus showing typical characteristics of programmed cell death（PCD）. During secondary cell wall formation, no cell wall substances accumulated between terminal cell walls of neighboring VEs. In addition, terminal cell wall substances were disaggregated in the post secondary cell wall formation. Later, when the remnant terminal cell wall broke the third stage, perforation, occurred. Thus, for these successive stages of VE differentiation, the critical stage, when differentiation was not reversible, was at the start of secondary cell wall formation with succeeding VE differentiation similar to a typical PCD process.
出处
《浙江林学院学报》
CSCD
北大核心
2008年第4期431-436,共6页
Journal of Zhejiang Forestry College
基金
国家自然科学基金重点资助项目(39730350)
江苏省自然科学基金资助项目(BK2005132)
国家自然科学基金资助项目(30671657)
