Question

Tapetal cells are
a. Glandular or amoeboid
b. Glandular
c. Invasive
d. Ephemeral

Answer 1

Hint: Tapetal cells are large cells with more than one nucleus per cell. These are single layered cells with a large nuclei and prominent cytoplasm. They play an important role in growth and development of pollen grain.

Complete answer:
In a flowering plant, tapetum is the innermost specialised layer of cells present within the anther. It is present just between the sporogenous tissue and the wall of another. It provides nutrition to the pollen grains for their complete growth and development. These cells undergo endomitosis, making the nucleus divide within the nuclear membrane, but cytokinesis doesn’t occur.

Thus it makes these cells to be either binucleated or multinucleated. Sometimes during the mitotic division of the sporogenous cells, the nuclei of the tapetal cells also divide, and as the result become multinucleated. It makes the nuclear constitution of these cells large which helps it provide nutrition to the growing pollen grains in their development.

Tapetum also helps in formation of pollen walls, transportation of nutrients, and synthesis of an enzyme called callase used in separation of microspore tetrad.
The cells of tapetum are large with a dense cytoplasm.

The tapetum is of two basic types based on the behaviour:
- Secretory/Glandular Tapetum
- Amoeboid/Periplasmodial Tapetum

In secretory type of cells, around the anther locule, a layer of cells is persistent. Later the cells break down but the cytoplasm remains in situ. In plasmodial type, the walls of the cells get dissolved and their protoplasts get fused, making it a multinucleate plasmodium. This happens because the cells break down during the early development and the movement of the cytoplasm to the locule is in the shape of amoeba, hence called amoeboid tapetum.

Hence, the correct answer is option (A).

Note: Glandular Tapetum has major importance in the secretion of pro-orbicules (small asexual structures of sporopollenin). These pro-orbicules get coated with sporopollenin and help in the formation of exile.