Main Difference – Syngamy vs Triple Fusion
Syngamy and triple fusion are two events of sexual reproduction of plants. Syngamy is the fusion of male and female gametes to produce a zygote. In triple fusion, a third sperm nucleus fuses with the central cell in the embryo sac, producing the endosperm. The main difference between syngamy and triple fusion is that syngamy is a type of generative fertilization whereas triple fusion is a type of vegetative fertilization. Syngamy occurs in animals and fungi as well. But, triple fusion only occurs in angiosperms.
Key Areas Covered
1. What is Syngamy
– Definition, Facts, Mechanism
2. What is Triple Fusion
– Definition, Facts, Mechanism
3. What are the Similarities Between Syngamy and Triple Fusion
– Outline of Common Features
4. What is the Difference Between Syngamy and Triple Fusion
– Comparison of Key Differences
Key Terms: Angiosperms, Endosperm, Gametes, Sexual Reproduction, Syngamy, Triple Fusion, Zygote
What is Syngamy
Syngamy refers to the fusion of gametes in fertilization. The two haploid male and female gametes are fused completely and permanently, forming a diploid zygote. The two types of gametes involved in syngamy are male gametes (sperm) and female gametes (ova). Sperms are small, microscopic cells produced by spermatogenesis. The ovum is large and non-motile and is produced by the oogenesis. The fertilization in plants is shown in figure 1.
Figure 1: Fertilization
Syngamy occurs in animals and fungi. Several types of syngamy can be identified based on different parameters.
Types of Syngamy
On the basis of the source of the gametes, syngamy can be divided into two as endogamy and exogamy. Endogamy is also known as self-fertilization. The gametes involved in endogamy are derived from the same parent (uni-parental). Exogamy is also known as cross-fertilization. The gametes of exogamy are derived from different parents (biparental).
On the basis of the structure of the gametes, syngamy can be divided into three types: isogamy, anisogamy, and hologamy. The gametes in isogamy are both morphologically and physiologically similar to each other. In anisogamy or heterogamy, the gametes are morphologically and physiologically different from each other. In hologamy, two organisms act as gametes.
What is Triple Fusion
Triple fusion refers to the fusion of a sperm cell with the two polar nuclei during the double fertilization in angiosperms. Double fertilization is the fusion of the egg nucleus by two male gametes. During pollination, the pollen grains are deposited on the stigma of a flower, facilitating the fertilization. Pollen contains two cells: a tube cell, which produces the pollen tube, and a generative cell, which produces two sperm cells. The germination of pollen grains on the stigma produces the pollen tube, which goes down the style until it reaches the micropyle in the ovule. Once it meets the micropyle, pollen tube bursts, releasing the two sperm cells which are carried through the pollen tube. One of the haploid sperm cells is fertilized with the haploid egg cell in the embryo sac, while the other haploid sperm cell fertilizes the central cell, which is also found in the embryo sac of the female gametophyte. Fertilization of the two gametes is called syngamy. The fertilization of a sperm cell with the central cell is known as triple fusion. As the embryo sac is fertilized twice, the fertilization of gametes in angiosperms is called double fertilization. The process of double fertilization is shown in figure 2.
Figure 2: Double Fertilization and Triple Fusion
The central cell consists of two polar nuclei. As the fusion of three haploid nuclei forms a triploid nucleus, the process is referred to the triple fusion. The triploid nucleus serves as the primary endosperm nucleus, giving rise to the endosperm of the seed, which stores nutrients of the seed.
Similarities Between Syngamy and Triple Fusion
- Syngamy and triple fusion are two later events of the sexual reproduction in plants.
- Both syngamy and triple fusion are involved in the fusion of cells.
Difference Between Syngamy and Triple Fusion
Definition
Syngamy: Syngamy refers to the fusion of gametes in fertilization.
Triple Fusion: Triple fusion refers to the fusion of a sperm cell with the two polar nuclei during the double fertilization in angiosperms.
Type of Fusion
Syngamy: In syngamy, a male gamete fuses with a female gamete.
Triple Fusion: In triple fusion, a male gamete fuses with the central cell.
Result
Syngamy: Syngamy produces the zygote that develops into the embryo.
Triple Fusion: Triple fusion produces the endosperm cell that develops into the endosperm.
Ploidy
Syngamy: The result of the syngamy is diploid.
Triple Fusion: The result of the triple fusion is triploid.
Type of Gametes
Syngamy: Both male and female gametes are involved in the syngamy.
Triple Fusion: Only male gametes are involved in the triple fusion.
Type of Fertilization
Syngamy: Syngamy is a generative fertilization.
Triple Fusion: Triple fusion is a vegetative fertilization.
Occurrence
Syngamy: Syngamy occurs in animals and plants.
Triple Fusion: Triple fusion occurs in angiosperms.
Conclusion
Syngamy and triple fusion are two types of events in the sexual reproduction of plants. Syngamy is the fusion of male and female gamete, producing the zygote. Triple fusion is the fusion of a male gamete with the central cell of the female gametophyte, producing the endosperm. The main difference between syngamy and triple fusion is the type of fusion of cells in each event.
Reference:
1. “Sexual Reproductions in Animals: Syngamy and Conjugation | Biology.” Your Article Library, 19 Feb. 2014, Available here.
Image Courtesy:
1. “Angiosperm life cycle diagram-en” By LadyofHats Mariana Ruiz – (Public Domain) via Commons Wikimedia
2. “Double Fertilization” By The original uploader was Triploid at English Wikipedia – Transferred from en.wikipedia to Commons (CC BY 3.0) via Commons Wikimedia
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