a Waseda Institute for Advanced Study ; Waseda University ; Tokyo , Japan.
Plant Signal Behav. 2014;9(12):e977715. doi: 10.4161/15592324.2014.977715.
Sex-possessing organisms perform sexual reproduction, in which gametes from different sexes fuse to produce offspring. In most eukaryotes, one or both sex gametes are motile, and gametes actively approach each other to fuse. However, in flowering plants, the gametes of both sexes lack motility. Two sperm cells (male gametes) that are contained in a pollen grain are recessively delivered via pollen tube elongation. After the pollen tube bursts, sperm cells are released toward the egg and central cells (female gametes) within an ovule ( Fig. 1 ). The precise mechanism of sperm cell movement after the pollen tube bursts remains unknown. Ultimately, one sperm cell fuses with the egg cell and the other one fuses with the central cell, producing an embryo and an endosperm, respectively. Fertilization in which 2 sets of gamete fusion events occur, called double fertilization, has been known for over 100 y. The fact that each morphologically identical sperm cell precisely recognizes its fusion partner strongly suggests that an accurate gamete interaction system(s) exists in flowering plants.
具有性别的生物体进行有性生殖，其中来自不同性别的配子融合产生后代。在大多数真核生物中，一个或两个性配子是能动的，并且配子主动相互接近融合。然而，在开花植物中，两性配子都缺乏能动性。两个精子细胞（雄性配子）包含在花粉粒中，通过花粉管伸长被被动输送。花粉管破裂后，精子细胞被释放到胚珠内的卵细胞和中央细胞（雌性配子）中（图 1）。花粉管破裂后精子细胞运动的精确机制仍然未知。最终，一个精子细胞与卵细胞融合，另一个与中央细胞融合，分别产生胚胎和胚乳。双受精是指两个配子融合事件的受精，这一现象已经被人们了解了 100 多年。每个形态相同的精子细胞都能精确识别其融合伴侣这一事实强烈表明，在开花植物中存在一个准确的配子相互作用系统。
