绿豆(Phaseolus aureus Roxb)大孢子发生和雌配子体发育

Megasporogenesis and Development of Female Gametophyta in Green Gram (Phaseolus aureus Roxb)

绿豆子厉由单心皮构成,1室,有9—13个弯生胚珠着生在边缘胎座上。胚珠具厚珠心双珠被。大孢原细胞1—3个。初生造孢细胞直接形成大孢子母细胞。减数分裂Ⅰ产生不均等大小的二分体,减数分裂Ⅱ为同步。4个大孢子线形排列,合点端为功能大孢子。胚囊发育为蓼型。3个反足细胞等大,早期退化。极核在受精前融合。助细胞在受精前未见退化。在成熟胚珠的合点端由珠心表皮细胞构成承珠盘结构,在珠孔端有珠心冠。

Green Gram s ovary consists of singe carpel, one locule, cantaining 9—13 campylotropous ovules bearing at the marginal placentation.Ovule is crassinucellate and bitegminous. There are Ⅰ—3 macroarchesporial cell. Primary sporogenous cell forms directly megaspore mother cell. Meiosis Ⅰ produces unequal dyad in size. Meioeis Ⅱ is synchronous. Four megaspores are arranged in a linear form. Functional megaspore lies at the chalazal end.Development of embryo sac is of Polygonum Type. Three antipodal cells of the same size degenerate at the early period. Polar nuclei fuse before fertilization. Synergid cells are not seen degenerated before fertilization, At the chaiazal end of the mature ovule, hapostase structure consists of epidermal cell of nucellus; At the micropylar end, there is epistase.