What is Microsporogenesis in angiosperm?

Microsporogenesis is the process in which each micropore mother cell divides meiotically to form four haploid microspores or pollen grains. The arrangement of pollen grain in a tetrad is affected by cytokinesis during meiosis. This results in the production of four cells by cell wall formation between the four nuclei.

What is Microsporogenesis process?

The nucleus of each microspore mother cell undergoes meiosis or reduction division and gives rise to four haploid nuclei. This process is called microsporogenesis. The partition walls between the sporangia get destroyed and the microspores are liberated by the dehiscence of the anther.

What is Microsporogenesis Where does it occur in angiosperm What is significance?

Microsporogenesis is an important process in plant reproduction, which includes several series of developmental stages from sporogenous cells to microspores. Any unpredictable disturbance during the meiotic process reduces gamete viability.

What is the difference between Microsporogenesis and Microgametogenesis?

Microsporogenesis is the process of formation of pollen grains (microspores) from the sporogenous tissue. Microgametogenesis is the process of formation of male gametes from the generative cell nucleus that is present inside the pollen grain through mitosis.

Which layer of anther is ephemeral?

cells situated just below the endothecium are known as middle layers. Cells of this layer are ephemeral and degenerate to provide nourishment to growing microspore mother cells.

What is a typical angiosperm anther?

A typical angiosperm anther is bilobed with each lobe having two theca, i.e., they are dithecous (Figure 2). The anther is a four-sided (tetragonal) structure consisting of four microsporangia located at the corners, two in each lobe. The microsporangia develop further and become pollen sacs.

What are the two major types of Microsporogenesis?

The two primary types of microsporogenesis – simultaneous and successive – differ in the relative timing of Meiosis II, though intermediate conditions have been reported in some species.

What comes first Microgametogenesis and Microsporogenesis?

The first stage is the microsporogenesis followed by the second stage, microgametogenesis, the process of transformation of a microspore in a pollen grain. Microspore development consists of an expansion of its volume, which is commonly associated with the formation of a vacuole.

What is Pollinium example?

A pollinium (plural pollinia) is a coherent mass of pollen grains in a plant that are the product of only one anther, but are transferred, during pollination, as a single unit. This is regularly seen in plants such as orchids and many species of milkweeds (Asclepiadoideae). Most orchids have waxy pollinia.

Is Microsporangia and microsporangium same?

Microsporangia are the structures that give rises to male gametes or microspores. It have been taken with plural form while microsporangium in singular way. On the other hand, the megasporangia are structures that give rise to female gamates or megaspores or ovules.

Is anther a Tetrasporangiate?

Anthers typically consist of two compartments called thecae (singular theca), with each theca containing two microsporangia (the fusion product of which is a locule). (Thus, anthers are typically tetrasporangiate.)

Why anther is called Tetrasporangiate?

The anther is four- sided i.e. it has four locules consisting of 4 microsporangia located in each locule which develops further and becomes the pollen sacs. Thus, the anther is tetrasporangiate because it’s four microsporangia. – Each stamen is composed of a slender stalk- like filament that supports the anther.

How are the two types of microsporogenesis determined?

There are two basic types of microsporogenesis as determined by the timing of cytokinesis, which is the formation of a plasma membrane and cell wall that divides one cell into two ( Figure 11.6A ). If cytokinesis occurs after meiosis I, then microsporogenesis is successive ( Figure 11.6B ).

How does microsporogenesis work in an apomictic plant?

Microsporogenesis does function in apomictics with resultant genetically recombined and chromosomally reduced male gametes. An apomictic plant must have some pollen fertility if it is to be used in a breeding program.

Where does microsporogenesis take place in the anther lobe?

The tapetal cells provide nutrition to the developing microspores. Tapetum secretes both enzymes and hormones. Tapetum is of two types-Secretory or glandular tapetum.and amoeboid or plasmodial tapetum. Pollen chamber: The pollen chamber forms the central cavity of anther lobe. The process of microsporogenesis takes place in the pollen chamber.

When does microsporogenesis occur after anaphase 2?

Microsporocyte at anaphase II of meiosis. Note that cytokinesis, resulting in cell wall formation, has occurred after meiosis I. C. Simultaneous microsporogenesis. Note lack of cell wall after anaphase II of meiosis.