大黍(Panicum maximum Jacq.)的胚珠附器

The Embellum in Guineagrass (Panicum maximum Jacq.)

摘要:

观察了大黍(PanicummaximumJacq.)胚珠附器的发生时间、位置和发育过程及其细胞化学特征。结果显示:(1)大孢子母细胞时期,珠孔端有一个或多个珠心表皮细胞开始伸长、膨大,特化为胚珠附器。(2)当胚珠附器伸长、膨大至最大程度时,胚珠附器细胞表现出显著的极性特征:细胞核位于细胞的珠孔端,大而清晰；细胞内同时形成了一个特大的液泡,几乎占据了整个细胞的合点端；细胞质则被挤到珠孔端一侧,集中分布在核的周围。(3)胚珠附器从开始出现到发育成熟,都没有淀粉粒的积累；但是,PAS反应显示胚珠附器细胞壁和细胞质都比普通珠心细胞的染色程度深,这说明其细胞壁和细胞内部富含可溶性多糖。

Abstract:

The development of embellum in guineagrass (Panicum maximum Jacq.) was observed under light microscope with traditional paraffin sectioning methods. At megaspore mother cell stage, one or more nucellar epidermal cells in micropylar end differentiated into embellum. As the ovule grew, the embellum developed more greatly and appeared to be enlarged and elongated. Mature embellums showed obvious polarity, the nucleus of which was near the micropylar pole of the cell. A big vacuolus almost occupied the whole chalazal pole. No starch grain accumulation was seen in embellum during its development in the present study, but its cell wall and cytoplasm were stained more densely than that of the common nucellar cells, suggesting that the embellum was full of soluble polysaccharide.