【摘要】 韭菜(Allium tuberosum)具有自发的卵细胞孤雌生殖和反足细胞无配子生殖现象。超微结构观察表明,成熟的卵细胞即有较高的代谢活性并在未受精的条件下发生类似合子中的某些变化,进而分裂为类似合子原胚的孤雌生殖原胚。三个反足细胞中,两个类似助细胞,一个类似卵细胞。卵状反足细胞可发生类似合子中的变化,导致分裂形成反足原胚。从超微结构角度对以上两种现象进行了讨论。更多还原

【Abstract】 Allium tuberosum Roxb is a species characterized by spontaneous parthenogenesis and antipodal apogamy. This paper deals with the ultrastructural changes’ during these processes. Before pollination, the mature egg cell contained abundant mitochondria with well developed cristae, spherical or ellipsoidal plastids and some polyribosomes, which suggested a relatively high metabolic activity .After fertilization, in zygotes the mitochondria changed to irregular shape and their cristae degenerated, the plastids elongated or became cup-shaped, the polyribosomes decreased and the free ribosomes increased in number. Some unfertilized egg cells, two days after anthesis, showed similar ultrastructural changes as those taking place in zygote, which teemed to be a sign of triggering to parthenogensis. In Allium tuberosum Roxb, the three antipo- dal cells bore a close resemblance to the egg apparatus: Among them two antipodal cells were similar to the synergids with a filiform apparatus-like structure and plentiful organelles at their chalazal end. The other was an egg-like antipodal cell which could undergo similar ultrastructural changes as those happened in zygote, leading to divide into apogamic proembryos two days after anthesis’. The problems of parthenogenesis and antipodal apogamy in Allium tuberosum Roxb is discussed in view of ultrastructural features of the egg and egg-like antipodal cell.更多还原