Reproduction in Fungi : Sexual reproduction

Human babies, baby animals or seeds of plants are all result of process called reproduction.

They all reproduce to make offspring that are similar to them.

When reproduction involves fusion of male and female gametes it is called sexual reproduction.

Higher organisms like plants and animals mostly reproduce sexually.

While lower organisms like bacteria mostly reproduce asexually as a single organism can produce offspring.

Fungi are unique group of organisms as they can show both asexual and sexual reproduction.

Asexual reproduction takes place by production of various types of spores.

While sexual reproduction is a complex process that involves many steps.

Let us now see how fungi reproduce sexually.

All fungi are made up of long tubular structures called as hyphae and they form a mass known as mycelium.

Male and female sex organs are produced on two different hyphae of either same mycelium or different mycelium.

These sex organs (also called as gametangia) produce unicellular sex cells or gametes.

The protoplasm of male and female gametes fuse together and this process is called as plasmogamy.

This fusion results in formation of a binucleate or dikaryotic cell and this phenomenon is called dikaryotisation.

Then, the two haploid nucleus present within the dikaryotic cell fuse together.

This process is known as karyogamy and it results in formation of a diploid nucleus or synkaryon.

At last, meiosis takes place resulting in formation of meiospores.

Meiospores are dispersed to form new offspring after getting suitable growth conditions.

Though steps of sexual reproduction is almost similar in all fungi.

But there are differences in the ways it takes place, hence there are many methods of sexual reproduction.

Let us see what are the methods of sexual reproduction in fungi.

Fusion of two compatible gametes resulting in formation of diploid zygote is called as planogametic copulation.

Isogamy, Anisogamy and Oogamy are the three different types of planogametic copulation.

Fusion between a male and a female gamete that are similar in morphology is called as isogamy.

When fusion takes place between a small, more active male gamete and large, less active female gamete, it is called as anisogamy.

While oogamy involves fusion between a nonmotile female gamete (egg) and motile male gamete (sperm).

When male gamete is transferred from male sex organ to female sex organ through a fertilisation tube, it is called as gametangial contact.

When protoplasmic contents of both male and female gametangia fuse to form a thick-walled zygospore, it is called gametangial copulation.

Spermatisation is another method in which small male gamete is carried to hyphae of female gametangium.

Fusion between two vegetative hyphae is called as somatogamy.

All these methods of sexual reproduction helps in creating genetic variability and new genetic combination.

Heterothallism is another phenomenon seen in fungi that promotes creation of genetic variability.

Existence of two genetically different but sexually compatible strains thalli in a species of fungi is called as heterothallism.

This prevents mating between two genetically similar organisms (inbreeding) and promotes mating between two genetically dissimilar organisms (called as outbreeding).

Heterothallism promotes production of offsprings with new genetic combination that helps in overcoming unfavorable conditions.

Revision

Fungi can reproduce by both asexual and sexual reproduction.

Plasmogamy, karyogamy and meiosis are the steps involved in sexual reproduction

Meiospores are produced after meiosis that are dispersed to produce new offspring.

Oogamy, anisogamy and isogamy are different types of planogametic copulation.

Gametangial copulation, gametangial contact, spermatisation and somatogamy are other types of sexual reproduction.

Heterothallism is seen in fungi to prevent inbreeding and promote outbreeding for production of offspring with new genetic combination.

The End