芝麻核雄性不育系ms86-1小孢子败育过程的超微结构

Ultrastructure in Microspore Abortion of Genic Male Sterile Line in Sesame(Sesamum indicum L.)

运用透射电子显微镜对芝麻核雄性不育系ms86-1的可育和不育花药进行了超微结构的比较观察。根据小孢子的细胞学形态特征,将芝麻花粉发育过程划分为小孢子母细胞形成期、减数分裂期、四分体期、单核小孢子早期、单核小孢子中期、单核小孢子晚期、花粉成熟期7个时期。对比观察表明芝麻核雄性不育的败育迹象起始于小孢子母细胞形成期,并伴随着进一步发育,败育现象逐渐明显,小孢子母细胞形成期小孢子母细胞壁形状不规则;减数分裂期小孢子母细胞壁严重扭曲变形,质膜外缺少早期外壁成分——原基粒棒;四分体期胼胝质壁外沉积物异常,呈绒毛状;四分体解体后形成畸形小孢子,孢子外壁不健全,绒毡层异常肥厚、降解延迟,释放极少量的畸形乌氏体;随后小孢子愈发皱缩,胞质凝集,内含物减少并逐渐凝聚成一团电子致密物质,最终走向完全败育。本研究揭示了不育小孢子的败育过程和败育特征,为深入研究芝麻核雄性不育败育机理奠定了基础。

Sesame （Sesamum indicum L.） is an important oil-seed crop with great nutritional value, and the sesame hybrid has remarkable heterosis in many characters, especially in productivity. To investigate the abortion mechanism of genic male sterile （GMS） line in sesame, a comparative study was conducted on the fertile and sterile microsporogenesis of ms86-1 derived from the male sterile line discovered by Osman using transmission electron microscopy （TEM） techniques. According to the morphologic characteristics of the microspores, the developmental process of sesame pollen could be tentatively divided into seven stages, including microsporocyte formation stage, microsporocyte meiosis stage, tetrad stage, early rnicrospore stage, middle microspore stage, late microspore stage, and pollen maturation stage, respectively. The abnormal phenomena observed in the sterile anthers indicated that male sterility might arise in microsporocyte formation stage. With the growth and development of the sterile anthers, the following abnormal features were observed evidently. The cell wall of the sterile microsporocytes was irregular during their formation stage. In the meiosis stage, the cell walls were getting distorted obviously, and the microsporocytes failed to form the early exine component designated as probaculums on the outside of the plasma membrane. Subsequently, abnormal villiform deposits were observed on the outside of the callose wall during the tetrad stage. As soon as the tetrad cells disintegrated, the re- leased sterile microspores represented aberrantly dumbbell-shaped, and their exines were undergrown without any baculum. Accompanying with the delay of the degeneration process, inclusions of the tapetum cells became more abundant and few abnormal ubisch bodies were secreted. Later on, the sterile microspore was gradually crimpled as its cytoplasm agglomerated to an electron dense clot, and ultimately degraded to the complete abortion. In this paper, compared with the fertile pollen development, the abortion process and characteristics of the sterile anthers were disclosed, providing a foundation for the greater insight into theabortion mechanism of GMS line in sesame.