芝麻核雄性不育系ms86-1微粉发生的细胞学观察

芝麻(Sesamum indicum)核雄性不育系ms86-1姊妹交后代表现为可育、部分不育(即微粉)及完全不育(简称不育)3种类型。不同育性类型的花药及花粉粒形态差异明显。Alexander染色实验显示微粉植株花粉粒外壁为蓝绿色, 内部为不均一洋红色, 与可育株及不育株花粉粒的染色特征均不相同。为探明芝麻微粉发生机理, 在电子显微镜下比较观察了可育、微粉、不育类型的小孢子发育过程。结果表明, 可育株小孢子母细胞减数分裂时期代谢旺盛, 胞质中出现大量脂质小球; 四分体时期绒毡层细胞开始降解, 单核小孢子时期开始出现乌氏体, 成熟花粉时期花粉囊腔内及花粉粒周围分布着大量乌氏体, 花粉粒外壁有11–13个棱状凸起, 表面存在大量基粒棒, 形成紧密的覆盖层。不育株小孢子发育异常显现于减数分裂时期, 此时胞质中无脂质小球出现, 细胞壁开始积累胼胝质; 四分体时期绒毡层细胞未见降解; 单核小孢子时期无乌氏体出现; 成熟花粉时期花粉囊腔中未发现正常的乌氏体, 存在大量空瘪的败育小孢子, 外壁积累胼胝质, 缺乏基粒棒。微粉株小孢子在减数分裂时期可见胞质内有大量脂质小球, 四分体时期部分绒毡层发生变形, 单核小孢子时期有部分绒毡层开始降解; 绒毡层细胞降解滞后为少量发育进程迟缓的小孢子提供了营养物质, 部分小孢子发育为正常花粉粒; 这些花粉粒比较饱满, 表面有少量颗粒状突起, 但未能形成覆盖层, 花粉囊腔中及小孢子周围存在少量的乌氏体。小孢子形成的育性类型与绒毡层降解是否正常有关。

Cytological Observation of Partial Sterility of Nucleic Male Sterile Line ms86-1 in Sesame (Sesamum indicum)

The progeny of the nucleic male sterile (NMS) line, ms86-1, in sesame (Sesamum indicum) display 3 types of pollen: fertile, sterile, and partially sterile. The differences in the three fertility types are reflected in the morphologic features of their anthers and pollen grains. Alexander’s staining revealed blue-green staining of outer walls of partially sterile pollen grains, and the inner walls were unevenly stained magenta-red, which differed from the staining of fertile or sterile pollen grains. To explore the mechanism of partial sterility, we compared the microsporogenesis of the three fertility types by electron microscopy. The microspores of fertile plants metabolized vigorously at meiosis as massive lipid globules accumulated in the cytoplasm. Tapetal cells began to degrade at tetrad stage, and some Ubisch bodies were secreted from tapetal cells at microspore stage. A large number of Ubisch bodies were inside and around the pollen sac at pollen maturation. The pollen exine surface, with 11–13 pieces of bulged strips, was covered with abundant bacula, which formed a close cover. Sterile plants showed abnormal microsporogenesis at meiosis. Lipid globules did not appear in the microspore cytoplasm, whereas callose began to accumulate around the cell wall at meiosis. Tapetal cells did not degrade at tetrad stage, and no Ubisch bodies were secreted at the microspore stage; A large number of aborted microspores presented in the pollen sac, without any normal Ubisch bodies, in microspore maturation stage. The microspore exine accumulated with callose except for bacula. In partially sterile plants, lipid globules were observed at meiosis. Parts of the tapetal cells began to distort at microspore stage and then degraded at that stage. The degradation of tapetal cells provided nutrition for the microspores with a developmental delay rhythm, and induced them to develop into normal pollen grains. These pollen grains were relatively plump, with a few granules on the surface, while the covering layer was not formed on the pollen exine. A few Ubisch bodies were observed in the pollen sac and around microspores. The fertility types of microspores during microsporogenesis agreed with the normality or abnormality of tapetum degradation.