Do you know what the above picture shows? Yes, you guessed it right- it is a bowl of mushrooms! Apart from various health benefits but some mushrooms are really delicious to eat when prepared right. However, there are other mushrooms, which can be extremely poisonous and hence are not edible. Mushrooms belong to the kingdom of fungi. While mushrooms are a type of fungi, so are yeasts, moulds, smuts etc and they all fall under the classification of fungi.
What is a fungus?
Image Credit: BBC Good Food
A fungus (plural form- fungi) is a eukaryotic organism which can be both unicellular as well as multicellular. A fungus is a heterotroph because it cannot prepare food for itself. It is also very important in maintaining the balance of nutrients within a particular ecosystem in which it resides. They are capable of both asexual as well as sexual reproduction and depend on other plants and animals for their food. They share a symbiotic relation with their host, that is while the host provides it with food, it also benefits the host. While some fungi have many beneficial functions, there are others which can cause serious harms and diseases to both animals and plants.
Fun Fact: If you devote yourself to the study and classification of fungi then you will be dealing with the science called mycology.
General characteristics of fungi
Here are some general characteristics features of fungi:
- They can be both unicellular, like yeast, and multicellular like mushrooms.
- Fungi are non-vascular.
- Multicellular fungi can have hyphae which are like filaments which branch out. These might be used for accumulating food for the fungus. A network of hyphae that is found in a fungus is collectively referred to as the mycelium.
- It has been seen that a fungus can go through both a sexual as well as an asexual phase in its life. This phenomenon is known as the alternation of generation.
- The food that is stored in the fungi is in the form of starch.
- The cell wall of fungi consists of chitin which is not typically found in the cell wall of other plants.
- Fungi are generally non-motile.
- Spores are used by them for reproduction which can be both sexual as well as asexual. While the asexual phase is known as anamorph, the sexual state is known as teleomorph.
- The nuclei that is observed in a fungi is rather small.
- Exoenzymes are produced by fungi. These enzymes help the fungi to first digest the food and then ingest it.
Modes of reproduction in fungi
There are mainly three ways through which fungi can reproduce- vegetative, sexual and asexual. The modes of reproduction also help in the classification of fungi.
Vegetative reproduction: There are a number of ways through which vegetative reproduction can take place- budding(appearance of a budding cell in the papilla of the parent cell and then forming multiple buds from there), fragmentation(multiplication through the process of breakage of the mycelium), Oidia(when the thallus of the fungus breaks into cells which then form a structure known as the oidium), fission(multiplying through the process of fission), chlamydospores(multiplication of through the production of some cells which are thick walled known as chlamydospores).
Sexual reproduction: Sexual reproduction is observed in almost all groups of fungi, apart from Deuteromycotina. It takes places through the various stages which are determined by the nuclear behaviour. During the plasmogamy phase the fusion of the two protoplasts takes place and in the next stage called the karyogamy, the fusion of the two nuclei takes place. Finally meiosis takes places.
Asexual reproduction: This is very commonly seen in most of the phyla under classification of fungi. This is again of three different types depending on the mode through which it takes place- sporangiospores ( spores that are non-motile which are present in the sporangium and these are thinly walled), zoospores(reproduction through zoosporangium) and conidia(formation of spores on branches known as conidiospores instead of the sporangium.
Classification of fungi
Based on their mode of reproduction, fungi can be classified into five distinct phyla- Zygomycota or the conjugated fungi, Chytridiomycota or Chytrids, Basidiomycota or club fungi, Ascomycota or sac fungi, and Phylum Glomeromycot. Let us take a look at this chart to know more about the classification of fungi and the characteristic feature of each phylum:
|Chytridiomycota or the Chytrids( this fungi has only one class- Chytridiomycetes)||· Primitive of all fungi
· One group has cellulose and chitin in cell wall, while others contain only chitin
· Mostly unicellular though some may form multicellular organisms
· Some live in aquatic environment while some also live in land
|Ascomykota or the Sac Fungi||· Forms a sac shaped structure known as ascus which is contains haploid ascospores
· Yeasts belong to this category and are used in baking purposes like many others belonging to this phylum
· Humans, animals and plants can be their hosts
· Asexual reproduction is common and frequent
· Yeasts produce through the process of budding
|Basidiomycota or the Club Fungi||· They contain spores present in a spore case called basidium. These spore cases are generally shaped like a club.
· A large number of spore production takes place.
· Spores hardly mature or germinate
· Alternation of generation is observed in their lifecycle
|Zygomycota or the Conjugated Fungi||· Multiply very rapidly on breads
· They are mostly saprobes, i.e. they get their nutrition from organic material which is decaying
· Parasites to mostly insects
· Contains a thallus of the coenocytic hyphae
· Unfavourable conditions leads to sexual reproduction
|Glomeromycot (a recent addition to mycology)||· Mostly associated with tree roots
· No sexual reproduction takes place
· Will not survive without roots of plants
· Has a monophyletic lineage, that is , they all come from a common ancestor
These are the most common divisions that have been observed in the kingdom fungi, each with its own defining characteristic features. For more bytes, keep following us here!