Egg Activation in Higher Plants: The Making of a New Generation in Angiosperms

AbstractThe male and female gametes of higher plants are immobile, but compatible gametes can recognize, attach, and fuse to fulfill fertilization and start embryogenesis after sperm cells are released from the pollen tube. The two fusions of egg and central cells with two sperm cells are controlled by accurate regulation mechanisms that ensure one-to-one gamete fusion. Many of the molecules involved in this process remain unknown, especially the egg cell proteins that are responsible for sperm–egg recognition, attachment, and fusion. The cytoplasm of sperm cells can trigger egg activation without the fusion of male and female gamete nuclei, suggesting that a gene controlling egg division is suppressed in the absence of fertilization. Fertilization in higher plants induces structural, physiological, and molecular biological changes in the fused egg, which are collectively known as egg activation. This review focuses on the early changes that occur in the fused egg of higher plants before fusion of the nuclei of male and female gametes.Keywords: Angiospermsegg activationegg divisionfertilizationsperm activation AcknowledgmentsThe authors thank Jennifer Smith, PhD, from Liwen Bianji (Edanz) (www.liwenbianji.cn/) for editing the English text of this manuscript.Disclosure statementThe authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.Additional informationFundingThis work was supported by the National Natural Science Foundation of China [Nos. 31170289].