Kingdom Fungi

What is Fungi?

Fungi is a heterotrophic, eukaryotic organism. Many times we find black dots on stale bread, yeast is used to make bread and beer, white spots on mustard leaves, mushrooms, are all examples of kingdom fungi. Fungi multiply and grow only under moist and warm conditions. Moreover, the total species of fungi that are known is more than 2,00,000.

Now that you are familiar with the fungi meaning, let us understand the other important aspects. 

Structure of Fungi

The structure of fungi contains the following:

  • It mainly includes four parts, namely:

- Sporangium

- Spores

- Food source

- Hyphae

  • Apart from unicellular yeasts, the fungi are filamentous. 

  • The fungi can be both multicellular or unicellular.

  • The fungi are formed of hyphae. The hyphae are long, thread-like structures. The network of hyphae forming a mesh-like structure is called mycelium.

  • The fungi contain a cell wall that is formed of polysaccharides and chitin.

  • The nucleus of the fungi contains chromatin threads and is dense.

  • A cell membrane surrounds the nucleus.

Characteristics of Fungi

The characteristics of fungi include the following:

  • The fungi are eukaryotic and non-vascular organisms. 

  • They do not contain chloroplast, which leads to the absence of photosynthesis.

  • The fungi grow slower compared to bacteria.

  • Both sexual and asexual modes of reproduction can take place in fungi.

  • Reproduction in fungi takes place through spores.

  • The nuclear envelope does not dissolve during mitosis.

  • Sexual reproduction in fungi happens because of the production of a chemical called Pheromone.

  • There is no embryonic stage in fungi.

Classification of Fungi

According to the fungi definition, they are classified mainly on two bases:

  • Based on nutrition mode

  • Based on spore formation

Based on Nutrition Mode

On the basis of nutrition, the fungi are classified as follows:

  • Saprophytic: They live and obtain their nutrition from dead organic matter. E.g., Penicillium, Rhizopus, Mucor, etc. These are mainly of two types, namely:

    1. Ectophytic saprophytes: The fungi grow on the surface.

    2. Endophytic saprophytes: The fungi grow inside the body of organic matter.

  • Parasitic: They obtain their nutrition from hosts, i.e., other living or dead organisms. They harm the hosts by causing disease conditions. The relationship between the host and parasite is called parasitism. 

The parasites are of two types, based on location:

    1. Endoparasite: They live inside the body of the host.

    2. Ectoparasite: They live on the surface of the host.

  • Symbiotic: They obtain their nutrition and grow on other living organisms. This allows the mutual benefit of both organisms. E.g., lichens and mycorrhiza.

Based on Spore Formation

On the basis of spore formation, the fungi are classified as follows:

Phycomycetes: 

  • We find these in moist surfaces, decaying wood or aquatic habitats. 

  • The mycelium is septate and coenocytic.

  • Some common examples include Mucor, Rhizopus and Albugo.

Ascomycetes: 

  • We commonly call these as sac-fungi.

  • They are mostly found in multicellular form and rarely in unicellular form. 

  • In ascomycetes, the mycelium is in a branched and separate form.

  • They are saprophytic, decomposers, or parasitic. 

  • Some examples include Aspergillus, Claviceps and Neurospora.

Basidiomycetes: 

  • They grow in soil, tree stumps or even logs.

  • Their mycelium is in a separate and branched form. 

  • The sex organs are absent.

  • Mushrooms are the most common form of basidiomycetes.

  • Some common examples include Agaricus, Ustilago and Puccinia. 

Deuteromycetes:

  • They are also known as imperfect fungi.

  • We only know the vegetative phase of these fungi.

  • They reproduce by conidia, which are the asexual spores.

  • Their mycelium is also in a separate and branched form.

  • Some common examples include Alternaria, Colletotrichum and Trichoderma. 

Reproduction in Fungi

The reproduction in fungi takes place in the following ways:

  • Sexual reproduction through oospores, ascospores and basidiospores.

  • Asexual reproduction through conidia, zoospores and sporangiospores.

  • Vegetative reproduction through fragmentation, budding and fission.

Uses of Fungi

The fungi have several uses, which include:

  • They are a substantial source of vitamin C (citric aid).

  • They are involved in the production of antibiotics, such as penicillin.

  • Fungi are used for food fermentation, including cheese and bread.

  • Mushrooms are a type of fungi and are edible.

  • They are used for brewing alcoholic beverages.

FAQ (Frequently Asked Questions)

1. How do Fungi Obtain their Food?

A. The fungi are heterotrophs, so they obtain their food and nutrition from host bodies.

2. How do Fungi Reproduce?

A. The fungi reproduce through three methods, namely:

  • Sexual

  • Asexual

  • Vegetative

3. What is the Mode of Nutrition in Fungi?

A. The fungi absorb their food from cell membranes and cannot ingest solid food as they are heterotrophs. The fungi cannot make their own food.

4. What is the use of Penicillin?

A. The penicillin is an antibiotic which is used to fight and treat several bacterial infections.

5. Who Coined the term ‘Fungus’?

A. Gaspard Bauhin gave the term fungus.