平邑甜茶(Malus hupehensis)胚囊种类与发生特性

Study on the development characteristics of different embryo sac types of Pingyi Tiancha (Malus hupehensis)

应用石蜡切片技术对结果期平邑甜茶的胚囊发生与形成过程进行了详细观察,以确定胚囊种类和发生特性。结果表明,平邑甜茶胚珠倒生,大孢子母细胞在盛花期前3～5d的花蕾期能减数分裂形成四分体并由合点端的大孢子发育成有性胚囊;到盛花期,多数有性胚囊败育,少数发育为八核胚囊。平邑甜茶的无性胚囊原始细胞始于盛花期前后靠近合点端的珠心细胞,并很快发育为单核无性胚囊,盛花后5～7d的坐果初期形成无性的八核胚囊。无孢子生殖胚囊可以单个发育,也可以多个发生而形成复合胚囊;其原始细胞发生的持续时间为10d左右。

Embryological investigation was carried out on the generation and formation of the embryo sac in the bearing plants of Malus hupehensis Rehd. var. pingyiensis by paraffin section method in order to determine the development characteristics of different embryo sac types. The results indicated that the plants of M. hupehensis Rehd. var. pingyiensis generated anatropous ovule. The macrosporocyte could form tetrad through meiosis that happened 3 to 5 days before full bloom, and only one megaspore near the chalazal end developed into reduced embryo sac. And then most of the reduced embryo sacs aborted and only a few could form 8-nuclei embryo sac till the full blooming stage. The aposporous initials, the nucellar cells in the chalazal end, developed during full blooming stage. Then it grew rapidly to unreduced embryo sac and formed 8-nuclei aposporous embryo sac, which happened 5 to 7 days after full bloom. The aposporous embryo sac might develop singly or numerously to form complex embryo sac, and the generating period of the aposporous initial cells could last about 10 days.