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林业科学 ›› 2012, Vol. 48 ›› Issue (12): 31-38.doi: 10.11707/j.1001-7488.20121205

• 论文 • 上一篇    下一篇

沙冬青根瘤的组织、超微结构及糖蛋白的亚细胞定位

何恒斌, 王华, 贾桂霞   

  1. 北京林业大学园林学院 国家花卉工程中心 北京 100083
  • 收稿日期:2012-10-09 修回日期:2012-11-28 出版日期:2012-12-25 发布日期:2012-12-25
  • 通讯作者: 贾桂霞

Nodule Histology and Ultrastructure of Ammopiptanthus mongolicus and Subcellular Localization of Glycoprotein in Nodules

He Hengbin, Wang Hua, Jia Guixia   

  1. National Engineering Research Center for Floriculture College of Landscape Architecture, Beijing Forestry University Beijing 100083
  • Received:2012-10-09 Revised:2012-11-28 Online:2012-12-25 Published:2012-12-25

摘要:

沙冬青是我国西北荒漠地区仅有的2种常绿阔叶灌木之一,能够与根瘤菌形成根瘤。研究表明,沙冬青成熟根瘤表现出"无限型"根瘤的典型特征,由根瘤顶端到底部依次为: 无根瘤菌的分生组织区(Ⅰ区)、细胞开始分化的侵染区(Ⅱ区)、固氮区(Ⅲ区)和老化区(Ⅳ区)。沙冬青根瘤除Ⅰ区分生组织外,由外向内依次为:皮层、内皮层、维管束、薄壁细胞层和侵染组织。沙冬青正常根瘤属于典型的胞内侵染方式,畸形根瘤侵染格局却呈现出胞间侵染的特点。透射电镜观察显示,沙冬青根瘤的Ⅱ-Ⅲ过渡区呈现多样化细胞,表现出丰富的细胞学过程:1)根瘤菌被释放后,寄主细胞启动类菌体周膜的装配过程,内质网将合成的膜物质以小泡的形式向根瘤菌周围运输,形成完整的类菌体周膜,类菌体周膜继而发生融合、扩大,将多个根瘤菌包被在同一个周膜中; 2)相比于其他区域,Ⅱ-Ⅲ区的侵染细胞中存在较多的淀粉粒; 3)相邻的侵染细胞间存在较为丰富的胞间连丝。糖蛋白细胞定位显示, 在沙冬青根瘤薄壁细胞中,糖蛋白层位于细胞内壁表面,结构比较疏松。细胞被侵染后,在侵染细胞间隙或者侵染细胞与非侵染细胞间隙,有大量的糖蛋白颗粒附着在细胞壁外侧,并有少数游离在细胞间隙。

关键词: 沙冬青, 根瘤, 组织, 超微结构, 糖蛋白

Abstract:

Ammopiptanthus mongolicus is one of the only two ever-green shrub species in the north-west China deserts, and is able to form nodules with rhizobia as an ancient legume. In this study, histology of root nodules of A. mongolicus was analyzed. Nitrogen-fixing nodules showed typical characteristics of indeterminate nodules, and from the distal (apical) part of a nodule to the proximal (basal) region, four central zones were able to be distinguished: the bacteria-free meristematic zone I; infection zone II, in which the cells began to differentiate; nitrogen-fixing zone III; and senescent zone IV. Exception for the apical meristem, the other three zones were surrounded by lateral nodular tissues such as the parenchyma (i.e ., the inner cortex), the vascular bundles, the endodermis and the cortex, successively. Intracellular infection was observed in A. mongolicus normal nodules, while intercellular infection characteristic was shown in abnormal nodules. Ultrastructural observation showed that the region between zone II and III contained diversified cell types, exhibiting diverse cell processes: 1) After bacteria were released, host cells initiated the assembling process of perbacteriod membrane, during which vesiculars were engaged in transporting membrane materials to bacteria vicinity from endomembrane reticulum. Intact perbacteriod membrane was formed and contained a single bacterium, afterwards adjacent membranes were fused and enlarged to form a large peripheral membrane which wrapped several bacteria. 2) Compared to other regions, interzone II-III contained much more starch granules. 3)Many plasmodesmata existed between contiguous infected cells. Electron microscopy cytochemistry studies showed that glycoprotein grains in a loose form were located at internal wall of parenchyma cells. After being infected by bacteria the glycoprotein was translocated into the intercellular spaces between infected cells or between infected and un-infected cells, where most glycoprotein grains were attached to the external wall with some dissociated.

Key words: Ammopiptanthus mongolicus, nodule, histology, ultrastructure, glycoprotein

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