Explain double fertilisation in plants ?
Double Fertilization
In plants, reproduction is attained by fertilization; more precisely double fertilization.
Read on to explore how is double fertilization achieved and its significance.
Double Fertilization Definition
“Double fertilization is a complex process which involves the fusion of one female gametophyte with two male gametes”
What is Double Fertilization?
Double fertilization is a chief trait of flowering plants. In the phenomena, one female gamete unites with two male gametes. One of the male gametes fertilizes the egg resulting in the formation of a zygote and the other unites with 2 polar nuclei for the formation of an endosperm.
Double fertilization provides stimulus to the plant resulting in the ovarian development to fruits and development of ovules into the seed. When the haploid male gametes and female gametes fuse, the diploid state of the plant is restored.
Double Fertilization Process
The process of double fertilization is explained below:
Double Fertilization in Angiosperms
Angiosperms are flower-bearing plants and are the most diverse group of terrestrial plants. The flowers form the reproductive part of angiosperms with separate male and female reproductive organs. Each contains gametes – sperm and egg cells, respectively.
Pollination helps the pollen grains to reach stigma via style. The two sperm cells enter the ovule-synergid cell. This proceeds to fertilization.
In angiosperms, fertilization results in two structures, namely, zygote and endosperm, hence the name “double fertilization.”
Double fertilization is a complex process where out of two sperm cells, one fuses with the egg cell and the other fuses with two polar nuclei which result in a diploid (2n) zygote and a triploid (3n) primary endosperm nucleus (PEN) respectively.
Since endosperm is a product of the fusion of three haploid nuclei, it is called triple fusion. Eventually, the primary endosperm nucleus develops into the primary endosperm cell (PEC) and then into the endosperm.
The zygote becomes an embryo after numerous cell divisions.
Explain double fertilisation in plants ?
**Double fertilization in plants**
Double fertilization is a unique reproductive process that occurs in flowering plants or angiosperms. It involves the fusion of two sperm cells with two different female gametes, resulting in the formation of two distinct structures - the zygote and the endosperm. This process is essential for the successful development of the embryo and the formation of nutritious endosperm, which supports the growth of the developing embryo.
**Process of double fertilization**
Double fertilization can be divided into two main steps:
1. **Pollination**: The process of double fertilization begins with pollination. Pollination is the transfer of pollen grains from the anther (male reproductive organ) to the stigma (female reproductive organ) of a flower. This can occur through various means, such as wind, insects, birds, or other animals.
2. **Double fertilization**: Once the pollen grain reaches the stigma, it germinates and produces a pollen tube. The pollen tube grows down the style, a long tube-like structure, towards the ovary, where the female gametes are located. The process of double fertilization involves the following steps:
a. **Syngamy**: One sperm cell from the pollen tube fuses with the egg cell (oocyte) present in the embryo sac, forming a zygote. This is called syngamy or fertilization. The zygote contains the combined genetic material of both the male and female parent plants.
b. **Triple fusion**: The second sperm cell from the pollen tube fuses with two polar nuclei present in the central cell of the embryo sac. This fusion is known as triple fusion or endosperm formation. The resulting structure is called the primary endosperm nucleus.
**Significance of double fertilization**
Double fertilization is a crucial process with several significant outcomes:
1. **Embryo development**: The zygote formed through syngamy develops into an embryo, which eventually grows into a new plant. This ensures the continuation of the plant species.
2. **Endosperm formation**: The primary endosperm nucleus formed through triple fusion develops into the endosperm. The endosperm is a nutritive tissue that provides nourishment to the developing embryo. It is rich in carbohydrates, proteins, and other nutrients, essential for the growth and development of the embryo.
3. **Seed formation**: After double fertilization, the zygote develops into an embryo, surrounded by the endosperm. The ovule, which contains the embryo and the endosperm, develops into a seed. The seed is a protective structure that houses the embryo and contains all the necessary nutrients for the germination and growth of the new plant.
In conclusion, double fertilization is a unique reproductive process in flowering plants. It involves the fusion of two sperm cells with two different female gametes, resulting in the formation of a zygote and the development of the endosperm. This process ensures the successful development of the embryo and the formation of a nutritious seed, essential for the growth and propagation of the plant species.
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