小金海棠雌蕊无融合生殖发育的解剖学结构观察

对小金海棠花期前后的雌蕊石蜡切片后进行观察,结果表明,小金海棠为倒生胚珠,厚珠心,双层珠被;孢原细胞和珠心组织细胞都可以发育,不经减数分裂发育成胚囊母细胞,进一步发育成单核胚囊,经3次有丝分裂发育成7细胞8核的胚囊,其中的二倍性卵细胞短暂休眠后不经受精直接发育成胚,中央细胞不受精发育成核型胚乳,属于未减数胚囊无融合生殖。同一胚珠中胚囊母细胞多途径起源或多胚囊发育现象普遍,但多数败育,推测多胚囊结构间竞争所造成的发育细胞的解体,是小金海棠果实出种率低或种子空瘪粒多的重要原因。

Anatomical characters of apomixis development in the gynoecia of Malus xiaojinensis

The observation was taken on gynoecia sequential paraffin slides made from flower buds of Malus xiaojinensis sampled before and after florescence. The results showed that the ovule of M. xiaojinensis was anatropous type in which the nu- cellus was crassinucellate. The archesporial cell and nucellus cells developed directly into embryo sac mother cells omitting meiosis phase during the developmental course. Embryo sac mother cells then further developed into 1-karyon embryo sac and mature embryo sac containi...