栽培甜菜中央细胞受精前后的超微结构

应用透射电镜技术比较栽培甜菜(Beta vulgaris)中央细胞受精前后的超微结构特征,以完善甜菜生殖生物学研究,并为相关研究提供基本资料。结果表明,中央细胞在受精前后的超微结构变化主要表现于核及核周围胞质。中央细胞的2个极核融合较早,在花蕾时期即以次生核形式存在,具双相核仁,可明显分辨纤维区和颗粒区;有的有额外小核仁和核仁液泡。核周围的细胞质中具丰富的细胞器且功能活跃,包括线粒体、质体(含或不含淀粉粒)、高尔基体、核糖体和粗面内质网。受精后,形成初生胚乳核,核周围胞质中变化最大的是质体,形成众多变形质体,形态多样,且富含淀粉粒。初生胚乳核分裂过程中,核仁消失,核膜崩解为囊泡状结构,粗面内质网减少,滑面内质网增加。分裂形成2个胚乳游离核,核周围胞质与初生胚乳核相似。总之,中央细胞在受精前后的超微结构特征均呈现代谢活跃状态。

Ultrastructure of Central Cell before and after Fertilization in Sugar Beet (Beta vulgaris)

The ultrastructural changes of central cell before and after fertilization were studied with TEM to provide more information for reproductive biology of sugar beet and relative research. The results indicated that the changes of central cell before and after fertilization mainly occurred in nucleus and cytoplasm around. Fusion of polar nuclei took place early at bud stage. The nucleolus of secondary nucleus was bipolar with notable fibrous and particle core. Sometimes, there was extra small nucleolus and nucleolus vacuole. Cytoplasm surrounding secondary nucleus was rich in organelles, including mitochondria, plastids with or without starch grain, Golgi body, ribosomes and rough endoplasmic reticulum (rER). After fertilization, a striking feature of cytoplasm surrounding nucleus was the well developed amoeboid plastids, which were numerous and various, filling with starch gains. Soon after that, primary endosperm nucleus divided into two free nuclei. During division, nucleolus disappeared and nuclear membrane disintegrated into small vesicles. Also, there was an obvious decrease in rER and an increase in smooth endoplasmic reticulum (sER). Overall, central cell was active before and after fertilization.