芝麻(Sesamum indicum L.)小孢子发育的超微结构

The Ultrastructural Studies on the Development of Microspore in Sesame(Sesamum indicum L.)

应用电子显微镜技术对芝麻(Sesamum indicum L.)小孢子发育进行了研究。在减数分裂前,小孢子母细胞含有丰富的细胞器。核膜有很多核孔,且有较大的通道。各小孢子母细胞之间通道明显,有强烈的物质交换作用。小孢子母细胞减数分裂为同时型。四分体小孢子中质体位于一侧,高尔基体含量增加。有丝分裂形成的营养细胞与生殖细胞由胼胝质壁隔开。生殖细胞中无高尔基体,少量质体呈退化状态。游离后的生殖细胞由两层质膜包围,这两层质膜有时膨大成很宽的隔间。营养细胞中细胞器在数量和大小上显著增长,在质体中迅速积累淀粉。花粉粒成熟时为2-细胞花粉粒。在四分体时小孢子形成原外壁,游离后原外壁上沉积孢粉素,形成外壁外层,在萌发沟处无外壁外层。

The development of microspore of sesame(Sesamum indicum)was investigated under elec- tron microscopy.Before meiosis,organelles in microspore mother cell(MMC)showed polarized distribu- tion.The plastids distributed near the cell wall.There were many nuclear pores and channels on nuclear membrane.Cytomictic channels were obvious between adjacent microsporocytes.The meiosis of MMC be- longed to simultaneous type.The content of dictyosome increased and plastids distributed regionally in mi- crospore tetrad.The nucleus of microspore underwent mitosis division forming a big and a small cells which were separated by callose wall.There were no dictyosome presented but a little degenerated plastids in the generative cell.After the callose wall disappeared,two layers of membrane around the free genera- tive cell and partially expanded into light electrondence chamber.The content and size of organelles in- creased obvious and starch was accumulated in protoplast in the vegetative cell.The microspore started to form the cellulose proexine at the tetrad stage.After the microspore released from tetrad,the sporopol- lenin deposited on the proexine.And then,the endexine,intine and ten to eleven mesoderm were initiat- ed.The successive mesoderm was formed in the mature pollen grain.