Question

Callase enzyme which dissolves callose of pollen tetrads to separate four pollen is provided by
A. Pollens
B. Tapetum
C. Middle layers
D. Endothecium

Answer 1

The enzymes is callase (β-1,3-glucan) is responsible for the proper development and maturation of fertile pollen since early as 1977, Stieglitz reported a significant increase in the callase activity in Lilium from the stage of tetrads awaiting the end of gametogenesis.

Complete Answer:
- Pollen is a powdery matter consisting of pollen grains which are male micro gametophytes of seed plants, which make male gametes that are sperm cells. Pollen grains have a rigid coat made of sporopollenin which protects the gametophytes throughout the process of their movement from the stamens to the pistil of flowering plants, or it may be from the male cone to the female coniferous plants.
- If pollen lands on a companionable pistil or female cone, it germinates by producing a pollen tube that transfers the sperm to the ovule containing the female gametophyte. Individual pollen grains are minute enough to require magnification to see detail. The study of pollen is known as palynology and is highly useful in paleoecology, paleontology, archaeology, and forensics.
- Pollen in plants is used for transferring haploid male genetic material from the anther of a single flower to the stigma of a difference in cross-pollination. In a case of self-pollination, this development takes place from the anther of a flower to the stigma of the same flower. The tapetum is a particular layer of nutritive cells found within the anther of flowering plants, where it is positioned between the sporogenous tissue and the anther wall.
- Tapetum is very important for the nutrition and development of pollen grains, as well as a source of precursors for the pollen coat. The cells are generally bigger and normally have more than one nucleus per cell. As the sporogenous cells go through mitosis, the nuclei of tapetal cells also divide.
- At times, this mitosis is not normal due to which many cells of mature tapetum become multinucleate. Occasionally polyploidy and polyteny can also be seen. The abnormally large nuclear constitution of the tapetum helps it in providing nutrients and regulatory molecules to the forming pollen grains.
- Endothecium which is a fibrous layer seen in angiosperms, the layer of cells lying beneath the epidermis of the wall of the anther. When the anther matures, thickenings often develop in the cell walls of the endothecium, probably aiding dehiscence.

So the correct answer is option B, tapetum.

Note: Tapetum secretes Ubisch bodies which get enclosed with sporopollenin and so increase the thickness of the pollen grain wall. It also secretes callase enzyme which dissolves callose substances by which four pollens of a pollen tetrad are combined, thus separating microspores or pollens of a tetrad.