美洲黑杨次生韧皮部筛管发育过程中原生质组分选择性自溶现象  

Phenomena of protoplasm components' selective autolyzing in the development of secondary phloem sieve elements in Populus deltoides

作　　者：尹增芳[1] 樊汝汶[1] 

机构地区：[1]南京林业大学森林资源与环境学院

出　　处：《北京林业大学学报》2007年第3期1-7,共7页Journal of Beijing Forestry University

基　　金：国家自然科学基金重点项目(39730350);江苏省自然科学基金项目(BK2005132)

摘　　要：观察次生韧皮部筛管分子发育过程中原生质组分的变化,对于研究筛管的生理功能具有重要作用.该文以美洲黑杨为实验材料,在电子显微镜下观察研究了次生韧皮部筛管发育过程.根据筛管细胞结构和原生质组分的系列变化,可将筛管发育过程划分为未成熟期、成熟期和衰退期.未成熟期是指筛管液泡膜破裂之前筛管的发育阶段,在这一时期内出现了细胞的径向扩展、壁的增厚以及筛管质体和P--蛋白质的产生.成熟期是筛管原生质组分发生选择性自溶,形成成熟筛管的阶段,以液胞膜的裂解作为分化开始的标志.在此时期内,筛管内的游离核糖体、高尔基体、内质网、细胞核等细胞器迅速解体消失.细胞核的降解存在两种截然不同的方式:①核膜早期降解,核质呈弥散状,这种弥散状的核质与由P--蛋白质构成的电子致密物相连;②染色质早期凝聚,后期核物质几乎完全降解,但核膜依然非常清晰.筛管衰退期以质膜开始解体作为标志.此时筛管质体的被膜裂解,淀粉类物质分散在筛管腔内,而线粒体是筛管内较迟降解的细胞器.后期筛板上产生胼胝质,筛管内P--蛋白质解体.在筛管原生质完全降解消失后,筛板处的胼胝质自溶,最后形成具开放筛孔的筛板,至此筛管完全失去功能.To do some researches on the physiological function of sieve tube elements （SE） in secondary phloem, it is key to observe the changes of plasm components during the development of SE. Using electronic microscopy, the development of secondary phloem SE was investigated in Populus deltoides. According to the changes of plasm components and cell structure, the development process of SE in secondary phloem could be divided into three stages, ie immature, mature and degenerated stages. The immature stage pointed to the development of SE before vacuole membrane was ruptured. In this stage, the cell radial expanding, cell wall incrassation, sieve element plastid and P-protein producing of SE occurred. The mature stage started when the vacuole membrane was ruptured. Whereafter, the protoplasm of SE autolyzed selectively, and the mature SE had being formed. In mature stage, the organelle, such as dissociative ribosome, Golgi body, endoplasmic reticulum and nuclear, was disassembled quickly. The nucleus was degenerated dissimilarly in two ways： 1） the nuclear membrane was degenerated earlier, and karyoplasm joined with P-protein was dispersed; 2） the chromatin was agglomerated earlier. Subsequently, the karyotin was almost degenerated, but the nuclear membrane still kept two layers structure clearly. The disassembled plasm membrane of SE was a sign in the degenerating stage. Meanwhile, plastid membrane was disorganized and the starch grain was dispersed in the chamber of SE. In addition, the mitochondria was dissembled at last. Synchronously, the callose appeared in sieve plate, and P-protein was disaggregated. Later on, the opened sieve plate was formed because of callose autolyzing after the protoplasm disappeared completely. Ultimately, the physiological function of SE was lost.

关 键 词：美洲黑杨 筛管 发育 原生质 选择性自溶 

分 类 号：S792.11[农业科学—林木遗传育种] S718.47[农业科学—林学]