The Concept of Spirogyra

Spirogyra are also called “water silk” or “pond silk” in some circles. The vegetative structure of these plants is filamentous and unbranched. Spirogyra is a genus that contains approximately 400 species. The genus Spirogyra is called after the spiral chloroplasts that are found in the cells of algae and are unique to this group of organisms.

Spirogyra classification 

Because of the existence of chlorophyll, Spirogyra is classed as a member of the Chlorophyta. There are over 400 species in this genus.

Spirogyra’s internal structure

1. The vegetative structure of Spirogyra is a filamentous thallus that is unbranched and unbranched.
2. The thallus is multicellular, with each cylindrical cell attached end to end to form a ring structure.
3. They range in width from 10 to 100 microns and can grow to be several centimetres in length. They appear as a slimy mass due to the presence of a mucilage sheath around the filament’s perimeter.
4. The cell wall is composed of two layers: the inner cellulose layer and the outside pectose layer. The decomposition of pectose in water results in the formation of a slimy mucilage sheath.
5. There are several organelles in each cell, including a nucleus, cytoplasm, a big central vacuole, and spiral chloroplasts.
6. Chloroplasts have a ribbon-like form and are organised in a spiral pattern. In a cell, there can be anywhere from 1 to 16 chloroplasts.
7. The chloroplast has a large number of pyrenoids arranged in a row. Pyrenoids are cells that store carbohydrates and protein.

Spirogyra Reproduction is a type of spirogyra.

Asexual, vegetative, and sexual reproduction are all possible in Spirogyra species. As with most other haplontic organisms, Spirogyra has a single dominant stage, which is a free-living haploid (n) gametophyte, and just one reproductive stage, the diploid zygote, during which the organism reproduces (2n)

The process of vegetative reproduction is fragmentation. Vegetative reproduction is the mode of reproduction that is preferred in favourable settings.

After being fragmented, the vegetative filament continues to develop into a new filament. Each fragment passes through a series of divisions and elongations before becoming a new filament.

It is possible that fragmentation is caused by mechanical injury or disintegration of the middle lamella as a result of changes in salinity and temperature in the water.

It is possible that the centre lamella of one cell will protrude into an adjacent cell, causing the filament to be broken in the process.

Asexual reproduction is present in only a few Spirogyra species, and it is a rare occurrence. Asexual reproduction occurs by the creation of azygospores, akinetes, or aplanospores, which are spore-like structures.

Unfavourable environmental circumstances favour the formation of aplanospores. The protoplast contracts and shrinks, forming a protective wall surrounding it. Aplanospores are formed as a result of this process.

Akinetes are also generated in a similar manner, but they have a thicker cell wall composed of cellulose and pectin than other bacteria.

Akinetes and aplanospores are non-motile spores that develop into a new filament under favourable conditions after the decay of the parent filament. Akinetes and aplanospores are found in the genus Akinetes.

Zygospores are also referred to as parthenos pores in some circles. The gametes that failed to fuse during sexual reproduction and developed into a new filament through asexual reproduction are referred to as asexual gametes.

Spirogyra are capable of reproducing sexually.

Spirogyra’s sexual reproduction is isogamous, which means that male and female gametes of similar size fuse together during the process of sexual reproduction.

Conjugation

Conjugationis the method of sexual reproduction. Scalariform conjugation and lateral conjugation are the two types of conjugation that exist.

Scalariform Conjugation: When two strands of Spirogyra sp come together and lie side by side, this is known as scalariform conjugation. Scalariform conjugation, also known as H-shape conjugation, is a type of conjugation in which the structure formed resembles a ladder.

Each cell of the two filaments that are lying together develops into a tube-like structure. A conjugation canal is formed between two cells after the tube-like structure has fused together.

The male gamete of one filament unites with a female gamete of the other filament, resulting in one filament being empty and the other becoming filled with zygotes.

These zygotes are discharged following the decomposition of the parent filament and germinate when the conditions are favourable.

Conjugation on the Lateral Axis:

In lateral conjugation, adjacent cells of a Spirogyra sp act as male and female gametes, respectively, for the first time. Conjugation tubes are generated between cells of the same filament when the filament is stretched. Lateral conjugation can be divided into two categories:

Passage between two adjacent cells is generated through the middle lamella in a process known as direct lateral conjugation. Male gametes mate with female gametes and form a zygote. Zygotes are generated in cells that alternate with one another.

Indirect lateral conjugation occurs when a cell containing a male gamete forms a canal that connects to an adjacent cell containing a female gamete, rather than directly.

The complete protoplast of a Spirogyra serves as a gamete in the organism. Aplano Gametes are the scientific name for them. As part of the gametangia formation process, which occurs at the end of Spirogyra’s growth season, aplano gametes are created.

Zygospores are the name given to the zygote in Spirogyra. When male and female gametes fuse together to generate zygospores, they form a diploid (2n) organism. Spirogyra has only one diploid stage in its life cycle, which is represented by zygospores.

The zygospore has a thick cell wall that is composed of three layers: the exosporium (the outer layer of cellulose), the meso sporium (the middle layer of chitin and cellulose), and the endospore (the inner layer of chitin and cellulose) (inner layer of cellulose).

The zygospore remains latent until a favourable environment is created for it to germinate.

When the zygospore germinates, it goes through meiosis, resulting in the formation of four haploid (n) nuclei, of which only one survives and the others dissolve.

The germ tube is formed when the developing zygospore bursts open. During development, the germ tube divides repeatedly by transverse division and produces a new haploid filament of the Spirogyra genus.

Conclusion 

Spirogyra are photosynthetic organisms that contribute significantly to the total amount of carbon dioxide fixation that occurs. They help to raise the level of oxygen in their environment. They are a food source for a variety of aquatic organisms.