【摘要】 成熟的甜菊(Stevia rebauaiana Bertoni)叶肉细胞通过回复变化转变成胚性细胞,需经历3个主要阶段:(1)起动阶段,细胞的主要特点是细胞质伸展,并向细胞中央伸出细胞质丝;同时,液泡蛋白体出现。(2)中间演变阶段:主要特点是细胞质桥形成;叶绿体脱分化成原质体;细胞核移向细胞中央。(3)终结分裂阶段即细胞脱分化终结,细胞分裂即将开始,主要特点是细胞处于分生状态,细胞核大而形状不规则,核仁疏松,具核仁小泡,核孔多而明显。生化分析表明在大量分生细胞形成时期,总核酸、RNA和可溶性蛋白质含量以及过氧化物酶活性达到高峰。但DNA含量变化不大。更多还原

【Abstract】 Authors deals with the changs of cell ultrastructure,nucleic acid and soluble protein contents as well as peroxidase activity during mesophyll cell dedifferentiation of leaf explant of stevia rebaudiana Bertoni. Electron microscopic observations indicated that the mature mesophyll cells had returning to meristematic cells had to go through three main phases: (1)Initiation phase: The main characteristics of cells in this phase were cytoplasmic expansion ,stretching out of cytoplasmic filaments to cell centre and appearance of the protein bodies in vacuoles. (2)Medial evolving phase:The main characteristics of cells in this phase were formation of cytoplasmic bridges;the chloroplasts were dedifferentiated to proplastids and the nuclei started to move toward centre. (3)Finishing and dividing phase: During this phase cell dedifferentiation had finished and cell division was about to start. The main characteristics of cells in this phase were the appearance of meristematic state; the nuclei, sometimes irregularly shaped, occupied a major proportion of the cell; the nucleoli were vaculated and the nucleopores increased in number and size. Biochemic analyses showed that the contents of the total nucleic acids,RNA and the soluble proteins as well as the peroxidase activity gradully increased during formation of meristematic cell aggregates and then reduced. However,the change of DNA contents was not obvious.更多还原