Development of polyspermic zygote and possible contribution of polyspermy to polyploid formation in angiosperms.
Development of polyspermic zygote and possible contribution of polyspermy to polyploid formation in angiosperms.
复制标题
多精受精卵的发育以及多精受精对被子植物多倍体形成的可能贡献。
DOI：
10.1007/s10265-017-0913-9
复制
发表时间：
2017
影响因子：
2.8
通讯作者：
Toda E.
中科院分区：
文献类型：
--
作者：
Okamoto T;Ohnishi Y;Toda E.
受精是真核生物单细胞和多细胞生物从雌雄配子单倍体基因组中恢复二倍体基因组的一般特征。在被子植物中，多倍体是一种普遍现象，多倍体在植物的长期多样性和进化成功中发挥了重要作用。关于同源四倍体植株的形成机制，认为三倍体与二倍体植株杂交的三倍体-桥途径是主要途径。对于三倍体植物的出现，未减数配子与减数配子的融合是普遍接受的。此外，还提出了玉米、小麦和一些兰花多精受精的可能性，尽管它被认为是形成三倍体的一种不常见的机制。多精受精之所以被认为是不常见的原因之一，是因为很难再现受精卵中的多精受精情况，也很难分析多精子三倍体合子的发育情况。最近，通过一个卵细胞和两个精子细胞的电融合，成功地产生了多精受精卵，并对其发育情况进行了监测。在多精受精卵中，两个精子核和一个卵核融合成一个合子核，三倍体合子通过有丝分裂形成具有典型的两极微管纺锤体的二细胞胚胎。二细胞原胚进一步发育并再生为三倍体植株。这些结果表明，多精植物受精卵具有形成三倍体胚胎的潜力，被子植物的多精受精可能是形成三倍体植物的途径之一。
Fertilization is a general feature of eukaryotic uni- and multicellular organisms to restore a diploid genome from female and male gamete haploid genomes. In angiosperms, polyploidization is a common phenomenon, and polyploidy would have played a major role in the long-term diversification and evolutionary success of plants. As for the mechanism of formation of autotetraploid plants, the triploid-bridge pathway, crossing between triploid and diploid plants, is considered as a major pathway. For the emergence of triploid plants, fusion of an unreduced gamete with a reduced gamete is generally accepted. In addition, the possibility of polyspermy has been proposed for maize, wheat and some orchids, although it has been regarded as an uncommon mechanism of triploid formation. One of the reasons why polyspermy is regarded as uncommon is because it is difficult to reproduce the polyspermy situation in zygotes and to analyze the developmental profiles of polyspermic triploid zygotes. Recently, polyspermic rice zygotes were successfully produced by electric fusion of an egg cell with two sperm cells, and their developmental profiles were monitored. Two sperm nuclei and an egg nucleus fused into a zygotic nucleus in the polyspermic zygote, and the triploid zygote divided into a two-celled embryo via mitotic division with a typical bipolar microtubule spindle. The two-celled proembryos further developed and regenerated into triploid plants. These suggest that polyspermic plant zygotes have the potential to form triploid embryos, and that polyspermy in angiosperms might be a pathway for the formation of triploid plants.