栽培甜菜卵细胞、合子及二细胞原胚的超微结构

为丰富被子植物生殖生物学资料,并为甜菜相关研究提供参考,应用透射电镜技术研究栽培甜菜(Beta vulgaris)卵细胞、合子和二细胞原胚的超微结构特征。结果如下:在成熟卵细胞中多聚核糖体数量不多,且细胞代谢活性较弱;初期合子内,核仁大量合成核糖体前体物质,胞质中多聚核糖体数目众多,细胞代谢活性较强;休眠期合子的核仁变小,胞质中核糖体数量急剧减少,仅有少量多聚核糖体,细胞代谢活性较弱;合子分裂前期和二细胞原胚期,核仁显著,胞质中核糖体的密度增加,出现大量多聚核糖体,细胞代谢活性较强。根据上述结果可以得出,栽培甜菜从卵细胞成熟→合子初期→合子休眠期→合子分裂前期→二细胞原胚的超微结构变化中多聚核糖体的变化最为显著,表现为"少→多→少→多"的数量变化过程,反映出细胞代谢状态也经历了"弱→强→弱→强"的变化过程,这种变化趋势与配子体世代向孢子体世代转变有关。

Ultrastructural Changes of Egg, Zygote and Two-celled Proembryoin Sugar Beet (Beta vulgaris)

We used transmission electron microscopy to study the ultrastructural changes in egg cell, zygote and two-celled proembryo of Beta vulgaris to provide information on the reproductive biology of angiosperms and related research into sugar beet. The mature egg cell was an inactive cell with only a few polysomes. At the early zygote stage, a large number of ribosomal precursors were produced by the nucleolus, and many polysomes appeared in the cytoplasm, which suggests a high level of metabolism. Zygote at the dormancy stage had a small nucleolus and marked decrease in ribosomes, as shown by a few polysomes, which suggests decreased metabolism. Zygotes in the prophase of mitosis and two-celled proembryo became active again in metabolism, for a prominent nucleolus, high density of ribosomes and increased number of polysomes in the cytoplasm. Polysomes change in number as “few-many-few-many” during the development of the egg, early zygote stage, zygote at dormancy, zygote in prophase of mitosis and two-celled proembryo in sugar beet, which indicates that such changes in metabolism as “low-high-low-high” activity may relate to the transformation from gametophyte to sporophyte generation.