—大白菜干烧心病发生过程中心叶组织Ca^2＋定位及超微结构变化

采用电镜细胞化学技术，研究了人为诱导大白菜干烧心病发生过程中心叶组织细胞的Ｃａ２＋定位和超微结构变化。结果表明，正常植株叶片细胞内钙主要分布于液泡、细胞壁和叶绿体的膜片层结构中；试验处理植株随着缺钙天数的增加，细胞壁膜上的钙被释放沉淀到细胞间隙，叶绿体片层膜上的Ｃａ２＋释放到胞液中。缺钙后期，细胞内钙沉淀明显减少。同时细胞结构改变，质膜内陷，叶绿体膜和内膜系统破坏；随后细胞壁中胶层解体，可见症状出现时，细胞内隔消失，细菌侵入细胞间隙

Changes of Ca 2 Compartmentation and Ultrastructure in Inner Leaves of Chinese Cabbage ( Brassica campestris ssp. pekinensis Olsson) during the Development of Calcium related Physiological Disorder

An incidence of tipburn of Chinese cabbage was induced using hydroponic culture system with Ca 2 absence in the medium. The changes of Ca 2 location and ultrastructure in inner leaves during development of tipburn were followed via electromicroscopic cytochemistry methods. Results showed that in normal cells the deposits of calcium antimonate were mainly located in the cell wall,the vacuoles and the envelope of chloroplast. However in Ca deficient leaves,Ca 2 was found to compartment in the cytosol in large quantity. Release of membrane associated Ca 2 to the cytosol and of wall associated Ca 2 to the intercellular spaces was observed. In serious Ca deficient leaves,the deposits of calcium antimonate in the cell decreased. In addition,under Ca deficiency condition,cell membranes of Ca deficient leaves were the first to be damaged,including chloroplast membranes,plasma membranes and nuclear membranes. Then the middle layers of cell walls disassociated,leaving an enlarged space between cells. In serious Ca deficient leaves,cell compartmentation was destroyed,chloroplast deformed,plasma separated from the wall and the whole cell constricted. Finally,bacteria invaded in the intercellular space.