水稻双受精过程的细胞形态学及时间进程的观察

Cytological Observation of Double Fertilization and Its Duration in Oryza sativa

应用常规石蜡切片和荧光显微镜观察水稻(Oryza sativa)受精过程中雌雄性细胞融合时的形态特征及时间进程,确定合子期,为花粉管通道转基因技术的实施提供理论依据。结果表明:授粉后,花粉随即萌发,花粉管进入羽毛状柱头分支结构的细胞间隙,继续生长于花柱至子房顶部的引导组织的细胞间隙中,而后进入子房,在子房壁与外珠被之间的缝隙中向珠孔方向生长,花粉与花粉管均具有明显的绿色荧光。花粉管经珠孔及珠心表皮细胞间隙进入一个助细胞,释放精子。精子释放前,两极核移向卵细胞的合点端;两精子释放于卵细胞与中央细胞的间隙后,先后脱去细胞质,然后分别移向卵核和极核,移向卵核的精核快于移向极核的精核;精核与两极核在向反足细胞团方向移动的过程中完成雌雄核融合。大量图片显示了雌雄性核融合的详细过程以及多精受精现象。水稻受精过程经历的时间表如下:授粉后,花粉在柱头萌发;花粉萌发至花粉管进入珠孔大约需要0.5小时;授粉后0.5小时左右,花粉管进入一个助细胞,释放精子;授粉后0.5-2.5小时,精卵融合形成合子;授粉后约10.0小时,合子第1次分裂,合子期为授粉后2.5-10.0小时;授粉后1.0-3.0小时,精核与两极核融合;授粉后约5.0小时,初生胚乳核分裂。

The fusion of female with male gametes and duration of double fertilization in Oryza sativa were studied by paraffin sectioning and fluorescence microscopy, to determine the stage of zygotes and provide basic information about the implementation of pollen-tube transgenic technology. Pollen grains germinated soon after pollination. Pollen tubes grew first into the intercellular space of branched penniform stigma and then through the intercellular space of transmitting tissue into the top of the ovary, further penetrating the ovary wall and primine to the micropyle. Green fluorescence was found in both pollen and pollen tubes. A pollen tube growing through the micropyle and interspace of the nucellus epidermis releases two sperms into one synergid. Two polar nuclei move to the micropylar end before sperm is released in a gap between the egg cell and central cell and subsequently taking off cytoplasm one after another. The sperm nucleus moving to the egg nucleus runs faster than the one to the polar nuclei. It fuses with the polar nuclei that are moving towards the antipodal cells at the chalazal end. Images showed the fusion process of male and female nuclei and polyspermous fertilization. Here we determined the schedule of fertilization in Oryza sativa. Pollen grains germinate soon after pollination. It takes about 0.5 h for a pollen tube from germination to arrive at the micropyle. About 0.5 h after pollination, the pollen tube releases two sperms into one synergid. At 0.5-2.5 h after pollination, the egg cell fuses with one sperm to form a zygote. About 10.0 h after pollination, the division of the zygote begins. The duration of the zygote lasts about 2.5-10.0 h. However, one sperm nucleus fuses with two polar nuclei at 1.0-3.0 h after pollination, and 5.0 h after pollination the primary endosperm nucleus begins to divide.