Triple fusion is described as fusion that occurs between two polar nuclei and the sperm nucleus in one cell. A triploid nucleus known as the Primary Endosperm Nucleus is formed during double fertilisation in a seed plant, and it is responsible for the development of the seed (PEN). The PEN will eventually develop into an endosperm. Angiosperms, which are sexually reproducing plants, are the primary hosts of this fusion.
Before we can understand reproduction in angiosperms and learn more about what triple fusion is, we must first understand the anatomy of the reproductive portions of the male and female plants, And, for a deeper understanding, wherein the process of fertilisation do we come across triple fusion, how it occurs, and what happens to the gamete that is generated as a result of triple fusion are all important questions.
What is the procedure for Triple fusion?
Let’s go over the steps involved in the process of triple fusion in the following sections:
- Germination and formation of the pollen tube occur when pollen grains fall into the stigma of a flower.
- The pollen tube enters the embryo sac from the micropylar end, passing through the style on its way there.
- Syngamy occurs when one of the male gametes combines with an egg cell, resulting in the formation of a zygote.
- The second male gamete unites with the two polar nuclei already present in the central cell to form a triploid primary endosperm nucleus, which is then released into the environment.
- As a result, the triple process is defined as the process that results in the fusing of three haploid nuclei.
A single primary gamete, as well as two polar nuclei, are engaged in this process.
What is the starting point?
Now that we have a better understanding of the phases involved in the process of triple fusion, let us discuss how the process gets started.
The zygote is generated by the fusing of the male gamete with the nucleus of the egg cell, which takes place during fertilisation. The zygote remains inactive for some time as it awaits the formation of the endosperm, which develops from the primary endosperm cell that results from the triple fusion process. The endosperm is responsible for providing sustenance for the expansion, till the embryo is formed before the development of the embryo from the zygote begins.
Pollination
Pollination is the process by which the pollen grain from the male anther is transferred to the stigma of the female flower, and vice versa. Pollination can occur by the use of abiotic factors like the wind or air, or through the use of animals (biotic agents). Wind pollination occurs when pollen grains are carried away by the wind and fall on an appropriate stigma, resulting in the pollination process taking place. Increasing pollen grain production is required for this procedure, yet the majority of pollen grains are left unfertilized because the likelihood of landing on a stigma is still a concern. Due to the attractiveness of nectar-producing flowers and the fact that only a few pollen grains adhere to the insects when they fall on the stigma of another plant when the insect eats nectar from a different plant, insect driven pollination is more specific than other types of pollination. In this situation, the blooms are more attractive to bees and other pollinating insects, and they also produce nectar for them.
Double fertilisation
Double Fertilisation is a term used to describe the process of fertilising twice.
As soon as the pollen grains settle on the stigma, the tube cell of the pollen begins to expand, which results in the germination of the pollen tube. After penetrating the stigma and growing towards the style, the pollen tube eventually reaches the base of the ovule. The two germ cells move through the course of pollen tube development until they reach the ovule, where they become fertilised.
One germ cell fertilises one egg cell of the female flower in the ovule, resulting in the formation of the zygote. Both nuclei are haploid at the time of fertilisation and become diploid following fertilisation. The zygote will later develop into an embryo, which will be the primary product of fertilisation.
Angiosperms, on the other hand, undergo a different type of fertilisation, in which two polar nuclei and a sperm cell fuse together to form a triploid cell. Triple Fusion is the term used to describe the event that occurs when three cells fuse to generate another cell Primary Endosperm Nucleus is the outcome of the fusion of secondary nuclei, which is formed as a result of this fusion.
Endosperm
Because endosperm development is faster than embryo development, the embryo grows in an environment that is adverse to his or her development. It divides and generates a triploid endosperm tissue as a result of this division. It contains food reserves that are used to supplement the nutrition of the embryo throughout development. The primary endosperm nucleus undergoes a series of nuclear divisions that result in the formation of free nuclei. The free nuclear endosperm is the term used to describe this stage of development. It eventually contributes to the formation of the cell wall. Using the delicate coconut as an example, the white kernel represents the cellular endosperm and the water represents the free nuclear endosperm.
The Endosperm’s Role in the Body
Once a fertilised egg has been produced twice, the endosperm’s principal duty is to provide nutrients to the developing embryo.
Embryo
a zygote is formed as a result of fertilisation that takes place between the egg cell and the male germ cell of the plant during the process of reproduction. The zygote then develops into an embryo, which is the primary cell responsible for transmitting information from the parent plants to the child.
Conclusion
The fusion of the male gamete with two polar nuclei within the embryo sac of the angiosperm is referred to as “triple fusion.” The term “triple fusion” refers to the merging of three haploid nuclei, which is how this process came to be known. It is responsible for the production of the endosperm. Most flowering plants produce an endosperm, which is a tissue that develops inside the seeds of their flowers after fertilisation. It forms a protective shell over the embryo and supplies nutrients in the form of starch, though it may also contain oils and proteins.