菘兰胚和胚乳的发育及营养物质的组织化学

EMBRYO AND ENDOSPERM DEVELOPMENT IN ISATIS TINCTORIA L. AND THE HISTOCHEMICAL STUDY OF ITS STORAGE RESERVE

菘兰(Isatis tinctoria L.)胚珠倒生,2层珠被,珠心退化,合点端有珠心形成的增殖组织。弯形胚囊含卵器及具2极核的中央细胞,中央细胞珠孔端侧壁具壁内突,反足细胞退化。胚发育属柳叶菜型,心形胚晚期,胚柄达最长,为785μm、基细胞具壁内突,鱼雷胚期胚柄退化。成熟胚细胞含大量直径为2.5—7.5μm球形蛋白质体,成分为大量蛋白质、植酸钙镁,不溶性多糖及脂肪。除原形成层细胞外,还含许多小形淀粉粒。在基本组织中,星散分布一些分泌腔,内含流动性颗粒或团块状物质,成分为蛋白质及少量不溶性多糖及脂肪。胚乳发育属核型,心形胚晚期,胚体、上部胚柄周围及U形胚囊底部外周的胚乳形成细胞,珠孔及合点端部的胚乳,直至弯形胚晚期,才完成细胞化。随着胚乳发育,胚囊珠孔及合点两端的壁内突愈益发达·两端及侧位的外层胚乳细胞的外周壁有壁内突。成熟胚期, 胚囊合点端有许多层胚乳细胞,外周2—4层细胞具发达的壁内突,珠孔端有少量胚乳细胞。胚囊周边有1—5层胚乳细胞。讨论了不同发育时期胚和胚乳的营养。

The ovule is anatropous and bitegmic. The nucellar cells have disorganized except the cha- lazal proliferating tissue. The curved embryo sac comprises an egg apparatus and a central cell with two palar nuclei and wall ingrowths on its micropylar lateral wall. The antipodal cells disapper. Embryo development is of the Onagrad type. The filament suspensor grows to a len- gth of 785 μp and degenerats at tarpedo embryo stage. The basal cell produces wall ingroW- ths on the micropylar end wall and lateral wall. The cells of mature embryo contain many globular protein bodies, 2.5—7.5 μm in diameter, composed of high concentration of protein and phytin, insoluble polysaccharide and lipid. The cells, except procambium, also contain many small starch grains. Some secretory cavities scattered in the ground tissue have liquid- like granules composed of protein, ploysacchaide and lipid. Endosperm development follows the nuclear pattern. At the late heart embryo stage, the endosperm around the embryo and the upper suspensor and the peripheral endosperm of the basal region of the U-shaped embryo sac becomes cellular. The endosperm at micropylar and chalazal ends remains free nuclear phase until the late bended cotyledon stage. Wall ingrowths at both micropylar and chalazal end wall and lateral wall of the embryo sac become more massive during endosperm develop- ment. Wall ingrowths also occur on the outer walls of the outer layer endosperm cells at both ends and lateral region of the embryo sac. When the embryo matures, many layers of chalazal endosperm cells including 2—4 layers of transfer cells, a few of micropylar endosperm cells and 1—5 layers of peripheral endosperm cells are present. The nutrients of the embryo and endosperm at different stages of development are also discussed.