About this Research Topic
Embryo production through the union of egg and sperm is a fundamental system for the birth of progeny in animals and plants. Flowering plants perform an additional union of the central cell and sperm cell, to give rise to the endosperm as the nurse tissue for embryo development. This sexual reproduction manner with two union events is called “double fertilization.”
The mechanisms leading to the success of double fertilization have been exposed by cytological studies, especially recent live-cell imaging analyses and discoveries of the proteins regulating the fertilization abilities of gametes. A pair of sperm cells are formed in each pollen grain or pollen tube, and egg and central cells develop in an embryo sac enclosed within the ovule tissue. The pollen tube germinates after pollination and grows from the tip and elongates in the pistil tissue, heading to the ovule. Finally, the pollen tube is attracted by the synergid cells located adjacent to the egg cell in the embryo sac. Once the pollen tube reaches one of the synergid cells, the pollen tube tip bursts, releasing the contents including the sperm cells between the egg cell and central cell. Thus, male and female gametes meet, then interactions between male and female gametes such as pairing, attachment, membrane fusion, plasmogamy, gamete nuclear migration, and karyogamy progress to complete double fertilization. If either or both fertilizations fail, a second pollen tube is attracted by the persisted synergid cell to recover the fertilization, whereas the persisted synergid cell fuses with the endosperm (SE fusion) when double fertilization is successfully achieved.
Plants have evolved such elaborate fertilization mechanisms to conserve and develop the species. The utilization of cytoskeletons for these dynamic fertilization processes also differs from animals. Consequently, flowering plants have thrived as the most diverse group among land plants. Humans have also modified flowering plants by crossbreeding for more than 300 years, creating cultivars. Understanding the whole mechanisms of plant sexual reproduction processes would be useful to broaden the chance of future plant breeding.
This Research Topic aims to cover direct or indirect regulation mechanisms for successful double fertilization. We welcome all types of articles, such as reviews, mini-reviews, methods, and original research articles. The focus will be on, but not limited to, the following topics:
- Regulators controlling fertilization. Functional and cytological studies of genes and proteins which regulate the successful double fertilization.
- Factors contributing to the fertilization ability of gametes, such as functional and cytological studies of genes and proteins regulating normal gametogenesis.
- Dynamics and interaction of gametes or the accessory cells in fertilization. Cytological studies of gamete behavior by imaging analysis of fixed or unfixed samples.
- New techniques and methods to analyze plant sexual reproduction processes. For example, techniques for gamete isolation and comprehensive analysis of gamete.
Keywords: Double fertilzation, Gametes, Accessory cells, Live-cell imaging, Gametogenesis, Cytological studies
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