【作者】 李园园；

【导师】 杨清；

【作者基本信息】 南京农业大学 ， 细胞生物学， 2006， 硕士

【摘要】 洋葱是世界上最重要的园艺作物之一，其杂种优势十分明显，选育一代杂交品种是洋葱育种的主要方向。洋葱花器小，单花结籽率低，人工去雄成本高，利用雄性不育系是配制杂交种子的有效途径。本研究采用光镜、电镜、DNA梯度技术和RAPD(随机扩增片段长度多态性DNA)分子标记技术，对江苏省农业科学院蔬菜研究所选育的两套不育系洋葱63A、70的CMS机理进行了初步研究，结果如下： 1、不育系63A及其相应保持系63B的小孢子发生与花药壁发育的显微结构，结果表明： ①花粉母细胞时期，保持系和不育系花药花粉母细胞均发育正常，但不育系花粉囊形状不规则，绒毡层发育迟缓。 ②四分体时期，保持系和不育系四分体形成正常，但两者中层和绒毡层差异较大。保持系中层细胞排列整齐，细胞核清晰可见，绒毡层细胞质浓郁发达；而不育系中层严重退化，绒毡层与药室壁完全脱离，细胞质浓缩、空泡化。 ③小孢子时期，随着小孢子发育成熟保持系中层、绒毡层已逐渐降解，但两者的核清晰可见；此时，不育系小孢子已经出现干瘪现象，聚集在一起，中层、绒毡层完全降解。 ④花粉粒时期，保持系花粉粒发育饱满，中层和绒毡层完全降解。而不育系空壳花粉粘在一起，形成粗线状，药室严重收缩。 2、不育系63A及其相应保持系63B的小孢子发生与花药壁发育的超微结构，结果表明： ①四分体时期，在电子显微镜下观察不育系花药绒毡层出现胞质收缩、染色质浓缩、内质网溢满和线粒体肿胀等细胞程序性死亡(PCD)的特点。 ②小孢子时期，在电子显微镜下观察保持系小孢子形成花粉壁，细胞器发育正常；不育系小孢子开始收缩，细胞器数目大为减少，内质网发育受阻，并出现同心圆结构，核糖体聚集，线粒体数目少，嵴不发达，内外膜解体，花粉内壁发育受阻。 3、不育系63A绒毡层PCD检测： 对不育系四分体时期花蕾DNA电泳检测，结果表明： 不育系四分体时期花蕾DNA可以呈现明显的DNA ladder，而保持系仅出现少量DNA降解。 综上所述，我们推测不育系小孢子败育与作为小孢子发育必不可少的疏导更多还原

【Abstract】 Onion is one of the most important vegetable crops in the world. The reported results show that onion possesse higher hybrid superiority. The selection of hybrid variety of first generation has become a main objective in onion breeding. Because of the small flower organ and the low seed-getting rate of single flower, the cost of the manpower castraction is high in onion hybrid seeds production. Using the male sterility line to confect the crossbreed seed is an efficient pathway. By using the technology of light microscopy, transmission electron microscopy, DNA ladder and the molecule mark of RAPD (Randomly Amplified Polymorphism DNA), the CMS of two male-sterile line 63A and 70 developed by the institute of Vegetable Crops of Jiangsu Academy of Agricultural Sciences was studied accidently. 1. The microstructural observations of the microspore and the anther wall① At the pollen-mother cell stage, the pollen-mother cells both in fertile anthers and sterile anthers could develope normally. But in the male sterile anther, pollen sacs were formed irregularly and the tapetum formation was incomplete at the pollen-mother cell stage.②At the tetrad stage, the pollen-mother cells in sterile and fertile anthers went through meiosis and formed normal tetrad while there were many differences between their middle layer and tapetum. In the fertile anther, the cell of the middle layer arranged in order and the nuclei of the tapetum and the middle layer were observed clearly. At the same time, the tapetum adhering to the endothecium developed completely possessing dense cytoplasm. The middle layer was degenerated completely and collapsed into a thin layer, the tapetal cells become vacuolated and dissociated from the pollen sac wall, followed by condensation of the tapetal cytoplasm at the tetrad stage.③At the microspore stage, although the tapetal cytoplasm degraded, the nuclei of the tapetum and the middle layer were observed clearly in fertile anther. However, the middle layer and the tapetum in the sterile anthers were degraded completely and更多还原