Question

Which of the following layers of anther wall helps in its dehiscence?
a. Epidermis
b. Middle layer
c. Endothecium
d. Tapetum

Answer 1

Hint: The cells are uninucleate and vacuolated and become radially elongated. The anther dehiscence is the final function of the anther that causes the release of pollen grains. The process is coordinated precisely with pollen differentiation, floral development, and flower opening.

Complete answer:
- Dehiscence is the splitting that takes place at maturity, along a built-in line of weakness in a plant structure to release its contents, which is common among fruits, anthers, and sporangia.

- The anther in angiosperms consists of 4 layers’ epidermis, endothecium, middle layer, and the tapetum.

- The anther wall is differentiated in 4 layers. The epidermis is the outermost layer which is protective in function. The endothecium layer lies beneath the epidermis and is usually single layered. The cells of endothecium become radially elongated and undergo maximum development for the dehiscence of anthers.

- Before dehiscence of the anther, the endothecium develops a fibrous and thickened portion made up of callose.

- The stomium is the region where dehiscence occurs. The degeneration of the stomium and septum cells is part of a developmentally timed cell-death program(apoptosis). The Expansion of the endothelial layer and subsequent drying is also required for dehiscence.

- The tensions of the endothelial tissue lead to the splitting of the anther. This tissue is usually one to several layers thick, with cell walls of uneven thickness due to uneven lignification.

- The cells lose water, and the uneven thickness causes the thinner walls to stretch to a greater extent. The tension is being created that leads to the anther being split due to weakness and releasing pollen grains to the atmosphere.

- Due to the hygroscopic nature, endothecium helps in the dispersal of microspores. Some endothecium cells, opposite to the partition between two sporangia, become thinly walled and constitute the stomium, the site through which pollen grains are released during dehiscence.

Hence, The correct answer is option (C). Endothecium helps in dehiscence.

Note: Endothecium is the layer that secretes materials that are essential for the proper maturation of the pollen grain. Tapetum is a specialized layer that provides nutrition and is important in the development of pollen grains.