Question

What is a post-fertilization event in flowering plants?

Answer 1

Fertilization :

1. The fusion of male and female gametes to form a zygote is called fertilization
2. Post fertilization in flowering plants includes Endosperm and embryo development, maturation of ovary into fruit, and ovules into seeds

Endosperm development:

1. During double fertilization, the fusion of triple haploid cells results in the formation of a triploid cell called primary Endosperm.
2. This PEN undergoes successive nuclear division to form a tissue called Endosperm.
3. The cells of Endosperm reserve starch as food and provide support to the developing embryo and during seed development, the Endosperm is utilized by the seed.

Embryo development:

1. The embryo is formed by the rapid cell division in the zygote.
2. The zygote divides after the formation of Endosperm.
3. The zygote first develops into a pro embryo and subsequently into a globular, heart shape and mature embryo.
4. The stages of embryo development are similar in both dicotyledon and monocotyledon plants but the structure of the embryo is different.

Dicot embryo:

1. The embryo in a dicotyledon plant consists of one embryonal axis and two cotyledons.
2. The portion of the embryonal axis above the levels of cotyledons is called epicotyl and the portion of the embryonal axis below the level of cotyledons is called hypocotyl,
3. The hypocotyls terminate in the root tip which is covered by a root cap.

Monocot Embryo:

1. The embryo in the monocotyledon plant contains only one cotyledon called the scutellum, situated at one side of the embryonal axis.
2. The portion of the embryonal axis above the scutellum is epicotyl and contains shoot apex and a few leaf primordia enclosed within a structure called coleoptile.
3. The lower portion of the embryonal axis terminates into a radical and root cap enclosed by an undifferentiated sheath called coleorhiza.

Seed development:

1. The ovary develops into fruit and ovules into seed
2. The seeds are formed inside fruits
3. A seed consists of a seed coat, cotyledons, and an embryonal axis.
4. Seed coat: The hard outer layer of the seed is called testa and the inner layer is called tegument.
5. A small opening on the seed coat is called a micropyle, which helps in the exchange of oxygen.
6. Cotyledon: The swollen and thick portion of seed due to preservation of food.

Embryonal axis: The root and shoot of the embryo form the embryonal axis, above thus grows into the shoot, and below this axis grows into the root.