Question

When vegetative cells of an egg form embryo, it is called
A. Diploid polyembryony
B. Apospory
C. Apomixis
D. Adventive polyembryony

Answer 1

The vegetative cells are those that are somatic in function. Except for the gametes, all other cells in the body are vegetative cells. They can be induced to form an embryo. Embryos, thus, formed are not fully naturalized and are subjected to degeneration but the stimulus of pollination is required additionally.

Complete step by step answer: Vegetative cells are those that are present along with the germ cells. Vegetative cells are also known as somatic cells and do not possess gametes. Thus they are generally not involved in the reproduction process. When pollination is stimulated, sometimes the vegetative cells get stimulated to develop directly into an embryo. These cells are diploid and do not require any fertilization. In this case, the developed embryos either degenerate or compete to survive. This is called adventive embryony. This process usually results in the formation of more than one embryo and thus known as Adventive polyembryony. Embryo refers to the building block of seeds in plants. After fertilization, when the zygote divides into two cells it is called an embryo that actively divides to form the seed.
Now let’s see each option in detail.
-The diploid polyembryony takes place when embryos develop from synergids after fertilization. Synergid is a supporting cell type that lies around the embryo sac. It helps in double fertilization.
-Apospory means the production of diploid gametes from the somatic cells or non-reproductive cells. No meiosis and spore formation takes place.
-Apomixis is a type of asexual reproduction in which plant formations take place from a seed without the occurrence of fertilization. It is also called reproduction from special generative tissues. The unfertilized egg develops into new individuals which are a clone of a parent like in parthenogenesis.
-Adventive polyembryony as described above is the formation of an embryo from vegetative cells of an egg.
Hence, option D is correct.

Note: The vegetative cells of the egg are present to provide food reserves for the pollen grain. Also, they help in delivering the gametes to the embryo sac of the ovule or egg. But sometimes they are induced by some factors to develop an embryo and this is not natural reproduction. Polyembryony is seen majorly in citrus fruits like orange and lemon.