Knox R B, Zee S Y, Blomstedt C, Singh M B
School of Botany, University of Melbourne, Parkville, Victoria 3052, Australia.
Department of Botany, University of Hong Kong, Pokfulam Road, Hong Kong.
New Phytol. 1993 Dec;125(4):679-694. doi: 10.1111/j.1469-8137.1993.tb03917.x.
Double fertilization appears to have evolved as a product of change directly related to an accelerated rate and timing of reproduction. In this review, the focus is on the angiosperm male gametophyte, where changes include a reduction in the number of mitoses, establishment of the male germ unit and involvement of both members of the pair of sperm cells in reproduction. The organization of the generative cell during mitosis indicates that there may be basic similarities between this process in plant and animal cells. The microtubular organization of generative cells alters after isoiation. However, mitosis in Allamanda, proceeds as usual during in vitro culture. The presence of actin microfilaments within generative cells has previously been shown in Rhododendron and here we provide further evidence that actin microfilaments are indeed present in generative cells. Two different kinds of intermediate-filament-like systems (IFS) are present in the generative cells of Allamanda: one in the cytoplasm and the other closely associated with the surface domain of chromosomes, both identified by the use of monoclonal antibodies. This is the first report of an IFS existing in the vegetative nucleus of pollen. Two alternate views have been proposed for the involvement of sperm cells in double fertilization of angiosperms. First, the chance hypothesis assumes that sperm fusions with the egg and central cell are random interactions. Second, the specific receptor hypothesis proposes that one of the pair of sperm (the true male gamete) is destined to fuse specifically with the egg. Support for this latter view has come from demonstrations of sperm cell dimorphism, both in size and content of mitochondria and plastids. The production of monoclonal antibodies which bind to surface domains on the reproductive cells of higher and lower plants, and specifically to the cytoplasm of generative and sperm cells also suggest that directed fertilization occurs. Recently, the existence of translatable mRNA pools within the generative and sperm cells indicates that, with the use of recent technological advances such as the polymerase chain reaction, the potential exists to identify male gamete-specific genes. Contents Summary 679 I. Introduction 680 III. A cell biological perspective 681 IV. Two hypotheses for double fertilization 687 V. Isolation of living sperm from flowering plants 687 VI. Sperm surface antigens of plants 688 VII. Molecular characterization 690 VIII. Conclusions 691 Acknowledgements 691 References 692.
双受精似乎是作为与繁殖速度和时间加快直接相关的变化产物而进化的。在本综述中，重点是被子植物雄配子体，其变化包括有丝分裂次数减少、雄配子体单位的建立以及一对精细胞中的两个成员都参与繁殖。有丝分裂期间生殖细胞的组织表明，植物和动物细胞的这一过程可能存在基本相似之处。生殖细胞的微管组织在分离后会发生改变。然而，黄蝉属植物的有丝分裂在体外培养期间照常进行。此前在杜鹃花属植物中已显示生殖细胞内存在肌动蛋白微丝，在此我们提供进一步证据表明生殖细胞中确实存在肌动蛋白微丝。黄蝉属植物的生殖细胞中存在两种不同类型的中间丝样系统（IFS）：一种存在于细胞质中，另一种与染色体的表面区域紧密相关，两者均通过使用单克隆抗体鉴定。这是关于花粉营养核中存在IFS的首次报道。关于精细胞参与被子植物双受精，提出了两种不同观点。第一种，随机假说认为精子与卵细胞和中央细胞的融合是随机相互作用。第二种，特异性受体假说提出一对精子中的一个（真正的雄配子）注定要与卵细胞特异性融合。对后一种观点的支持来自精子细胞二态性的证明，包括线粒体和质体的大小和含量方面。与高等和低等植物生殖细胞表面区域结合的单克隆抗体的产生，特别是与生殖细胞和精细胞细胞质结合的单克隆抗体的产生，也表明发生了定向受精。最近，生殖细胞和精细胞内可翻译mRNA库的存在表明，随着聚合酶链反应等最新技术进展的应用，存在鉴定雄配子特异性基因的潜力。内容摘要679 一、引言680 三、细胞生物学视角681 四、双受精的两种假说687 五、从开花植物中分离活精子687 六、植物精子表面抗原688 七、分子特征690 八、结论691 致谢691 参考文献692 。
