Fungi life cycle

The word 'Fungus' might conjure an image of a projection arising out of the soil with a button shaped or an umbrella shaped cap on its top. There are a lot more fungi than any person can ever imagine and not all of them resemble the image that comes to a person's mind. As there are numerous types of fungi, they must have different predecessors. However, their mechanism of life is mostly the same. Before a person begins to study or even know about the different types of fungi, at least a simple outline of their life is most essential.

The life of a fungus usually begins as a spore (Though some fungi may be born as a result of sexual reproduction). The spores are formed as a result of meiosis. These spores are then carried by sporangium. These spores are dispersed with help of wind, insects or some other agent of dispersal. When the spores land on any suitable medium and if favorable conditions are available for the growth of the fungus, each spore can germinate in to a new fungus. These spores are haploid and they give rise to sporangia that is asexual as well as some hyphae that can produce spores without the process of meiosis.

The sexual phase of fungus begins when haploid hyphae from two separate fungi meet and fuse with each other. As a result, the cytoplasm belonging to the two different cells fuse together. However, the nuclei of the two cells remain separate. The single hypha has two nuclei and is called as "Dikaryon". This may live for many years. Some dikaryons are believed to be alive for centuries. Dikaryons form sexual sporangia when the two different nuclei fuse together to form a single nucleus. Sexual sporangia are formed and the fungus undergoes meiosis to produce haploid spores. This entire cycle then repeats itself.

Fungi such as the Zygomcetes as well as the Chytrids have no diploid phase except for the phase of their life when sexual sporangia are involved. There are several fungi that have lost their ability to reproduce sexually. Such fungi are called as Fungi Imperfecti and can reproduce either asexually or by means of vegetative growth. The other fact is that fungi are heterotrophic just like animals. But they cannot eat like animals. They have to absorb nutrients from the medium on which they grow by means of their hyphae. The absorbed food is them broken down using special enzymes and is converted into a simpler form. This mechanism finds its usage in the brewing and baking industries.
Linus Orakles
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