Abstract

In angiosperms, after the egg fuses with the sperm, many structural, physiological, and molecular biological changes occur in the fertilized egg. All of these changes facilitate the conversion of the haploid egg into the diploid zygote, a process known as the maternal-to-zygotic transition (MZT). In the egg, fertilized egg, and zygote, changes occur at each stage under the control of exact spatio-temporal regulation mechanisms. This review focuses on the molecular biological changes that occur during zygote activation in higher plants including the following: maturation and activation of intrinsic parental transcription; zygote genome activation (ZGA), changes in the expression levels of genes from the zygotic genome; the effect of parental genomic dosage; and cellular determination of zygotic asymmetrical division. It is these exact spatio-temporal regulation mechanisms that allow the egg to convert into the zygote, undergo asymmetrical cell division, and initiate embryogenesis. The results of recent studies have shown that the regulation of zygotic division is a complex process occurring in the cell (egg, fertilized egg, and zygote). The results so far have revealed just the tip of the iceberg of zygote activation. More research is required to explore the regulation of zygote activation.

摘要

在被子植物中，卵子与精子融合后，受精卵会发生许多结构、生理和分子生物学的变化。所有这些变化都促进了单倍体卵子转化为二倍体合子，这一过程被称为母体-合子转换 (MZT)。在卵子、受精卵和受精卵中，在精确的时空调节机制的控制下，每个阶段都会发生变化。本综述重点关注高等植物合子激活过程中发生的分子生物学变化，包括：内在亲本转录的成熟和激活；合子基因组激活 (ZGA)，合子基因组中基因表达水平的变化；亲本基因组剂量的影响；和合子不对称分裂的细胞测定。正是这些精确的时空调节机制使卵子转化为受精卵，进行不对称的细胞分裂，并开始胚胎发生。最近的研究结果表明，合子分裂的调节是一个发生在细胞（卵子、受精卵和合子）中的复杂过程。迄今为止的结果仅揭示了受精卵激活的冰山一角。需要更多的研究来探索受精卵激活的调节。