question_answer

                        Explain the structure of a typical microsporangium with the help of well - labelled diagram. Also, highlight the major roles performed by the innermost layer of microsporangium.

Answer:

Microsporangium or pollen sac is a cylindrical structure that produces numerous spores, which give rise to the male gametophyte. It consists of two parts, i.e. an outer wall and a central sporogenous tissue. Microsporangial wall is made up of four different layers, i.e. epidermis (also known as common anther covering), endothecium, 1 - 3 middle layers and the tapetum (innermost layer).

Tapetum performs a number of functions as

(i) Nourishment of the developing microspore mother cells and pollen grains.

(ii) Production of lipid rich Ubisch granules.

(iii) Secretion of enzymes like callase, which is responsible for the degradation of callose wall around pollen tetrad.