J Integr Plant Biol. ›› 2000, Vol. 42 ›› Issue (8): 803-810.

• Research Articles • Previous Articles     Next Articles

Structural Association of Endoplasmic Reticulum with Other Membrane Systems in Populus deltoides Apical Bud Cells and Its Alterations During the Short Day-induced Dormancy

JIAN Ling-Cheng, SUN Long-Hua, LI Ji-Hong, WANG Hong, SUN De-Lan, Paul H LI   


A comparative study was carried out on the EM-cytochemical localization of calcium and Ca2+-ATPase activity in the suspension-cultured cells between the chilling-sensitive maize (Zea mays L. cv. Black Mexican Sweet) and chilling-insensitive Trititrigia (Triticum sect. Trititrigia mackey) at 4 ℃ chilling. When maize and Tyititrigia cells were cultured at 26 ℃, electron microscopic observations revealed that the electron-dense calcium antimonate deposits, an indication of the calcium localization, were localized mainly in the vacuoles, and few was found in the cytosol and nuclei. The electron-dense cerium phosphate deposits, an indication of Ca2+-ATPase activity, were abundantly distributed on the plasma membrane (PM). When the cells from both species were cultured at 4 ℃ for 1 and 3 h, an elevation of Ca2+ level in the cytosol and nuclei was observed, whereas the cerium phosphate deposits on the PM showed no quantitative difference from those of the 26 ℃-cultured cells, indicating that the enzymatic activities were not altered during these chilling periods. However, there was a distinct difference in the dynamics of the Ca2+ distribution and the PM Ca2+-ATPase activity between maize and Trititrigia when chilled at 4 ℃ for 12, 24 and 72 h. In maize cells, a large number of Ca2+ deposits still existed in the cytosol and nuclei, and the PM Ca2+-ATPase became less and less active, and even inactive at all. In Trititrigia cells, the increased cytosolic and nuclear Ca2+ ions decreased after 12 h chilling. By chilling up to 24 and 72 h, the intracellular Ca2+ concentration had been restored to a similar low level as those of the warm temperature-cultured cells, while the activity of the PM Ca2+-ATPase maintained high. The transient cytosolic and nuclear Ca2+ increase and the activities of PM Ca2+-ATPase during chilling are discussed in relation to plant cold hardiness.

简令成1* 李积宏1** 李本湘1*** 陈辉煌2

(1.Laboratory of Plant Hardiness,Department of Horticultyral Science, and Plant Biological Sciences Program, 2. Department of Horticulture, and Center for Gene Research and Biotechnology, Oregon State Unixersity,Corvallis,OR 97331, USA)

摘要:杨树 (Populusdeltoides Bartr.exMarsh)顶芽分生组织细胞经一种改良的高锰酸钾固定法固定后 ,显示出一种十分清晰的内膜结构 ,尤其展现了内质网与其他膜系统存在一种结构上的密切联系。一些与核膜相连接的内质网伸展到细胞质中与线粒体、质体及高尔基体发生联系 ,或延伸到质膜。还有些内质网的一端与一个细胞的核膜相连结 ,其另一端穿过胞间连丝与邻近的另一个细胞的核膜相连结 ,在两个相邻的细胞核之间形成一种结构上的“内质网桥”。这种“内质网桥”结构的揭示 ,进一步完善了共质体的概念。在植物细胞间 ,不仅通过胞间连丝造成细胞质的沟通 ;而且通过“内质网桥”形成核与核之间的联络。在短日照诱导的休眠过程中 ,内质网出现收缩现象 ,导致内质网与其他膜系统联系的中断 ,胞间连丝的中断 ,以及核与核之间“桥通道”的中断。在芽休眠被打破和复苏生长后 ,内质网的收缩现象消失 ,内质网与其他膜系统间联系 ,以及相邻细胞核之间重建“内质网桥”。这些结果揭示 ,内质网在沟通细胞核与各细胞器 ,以及核与核之间生命活动的关系上可能起着重要的作用。它的收缩作用可能导致生长的停止和休眠的发展

关键词: 内质网;内质网桥;内质网收缩;胞间连丝;休眠;杨树

Key words: Ca2+, plasmalemma Ca2+-ATPase, Ca2+-homeostasis, plant coldhardiness, maize, Trititrigia

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