平邑甜茶的无融合生殖及单性胚的发育

平邑甜茶的胚囊是由胚囊母细胞直接有丝分裂产生,而胚囊内无助细胞,因此为6核5细胞。胚由未经受精的卵细胞发育而成,因此在无融合生殖中届孤雌生殖。单性胚具有苹果属合子胚相同的发育途径,可分为8个时期:1.球胚前原胚期;2.小球胚期;3.球胚期;4.大球胚期;5.心形胚期;6.鱼雷胚期;7.幼胚期;8.成熟胚。原胚的发育属茄型。胚乳的发育属核型,当胚乳发育处于大球胚形成前,胚乳为游离核,当幼胚形成时,胚乳已形成细胞。当幼胚体积膨大为成熟胚时,则胚乳已解体。

AGAMOGONY AND DEVELOPMENT OF THE MONOGENETIC EMBRYO IN MALUS HUPEHENSIS REHD

The embryo sac in Malus hupehensis Rehd. is developed directly from the embryo mother cell through mitoses. The embryo sac without synergid has five cells with six nucleuses. The embryo is developed from the nonfertilized egg, so it is parthenogenetic. The developmental way of the monogenetic embryo is the same as that of the zygoembryo in Malus. It can be divided into eight stages: 1. proembryo before globular stage; 2. little globular stage; 3. globular stage; 4. lager globular stage; 5. heart-shaped stage; 6. torpedo-happened stage; 7. young and (8) mature stages. The development of the proembryo belongs to solanum type. The endosperm development follows the nuclear type. When the embryo develops before the lager globular stage, the endosperm development is at the free-nucleate stage. When the young embryo is formed, the endosperm goes into the cellular phase. When the young embryo is expanded to the mature one, the endosperm disintegrates.