Kingdom Fungi is one of the five kingdoms that are a part of the five kingdom classification given by R.H Whittaker. Fungi are eukaryotic organisms that are heterotrophic in nature and are found in moist and warm conditions. Some common examples of fungi are mushrooms, yeast, Penicillium, etc. Organisms that are neither plants nor animals belong to the Fungi Kingdom.
What is Fungi?
Fungi are eukaryotic organisms that have a well-defined nucleus and other cell organelles. Fungi are incapable of making their own food. They absorb nutrients from their surroundings. Fungi decompose the living matter around them and then feed on it. Hence, they are commonly called decomposers. These are mostly multicellular and some of them are unicellular. The most common fungi that is seen in our home is that on the bread. If kept outside for a long time, greyish patches appear on it. Edible fungi are the ones that can be eaten like mushrooms. The Fungi are capable of infecting plants, humans and animals.
Uses of Fungi
Fungi can be very useful and some of its uses have been listed as follows:
- Fungi help in maintaining the ecological balance as they act as decomposers and return the nutrients to the soil and atmosphere.
- These form symbiotic relationships with organisms like algae and help them with shelter in return of food.
- Fungi like Penicillium is used in making antibiotic which is used to treat diseases in humans.
- Fungi spores are sprayed across the crops and they help in killing pests and other insects.
- Fungi are used in producing food products such as bread, cheese, beer, etc.
Examples of Fungi
Here are few examples of fungi which are used commonly:
Structure of Fungi
Most of the fungi are multicellular but yeast is unicellular. The body of fungi is filamentous. They have long thread like structures which are called hyphae. These hyphae are collectively known as mycelium. The hyphae which are continuously connected and are filled with multi nucleated cytoplasm are called coenocytic hyphae. Others possess septae or cross walls in their hyphae.
The cell wall of fungi is made up of chitin and polysacchrides. Chitin gives strength to the cell wall. The nucleus is surrounded by a nuclear membrane and is very dense. Below is an image which gives a detailed view of the structure of fungi.
Kingdom Fungi Characteristics
Below are few of the important characteristics of Kingdom Fungi:
- The fungus is a non-vascular, eukaryotic creature.
- They lack chloroplasts, which prevents them from doing photosynthesis.
- Fungal reproduction happens by spores.
- The nuclear envelope does not degrade during mitosis.
- Sexual and asexual reproduction are both possible in fungi.
- Fungi do not possess an embryonic stage.
How Do Fungi Reproduce?
Reproduction is an important part of an organism’s survival. Asexual and Sexual reproduction are the two modes of this mechanism. Given below are important points:
- Fungi can reproduce both sexually and asexually. Anamorph refers to the asexual way of reproduction while Teleomorph refers to the sexual mode of reproduction.
- Conidia, zoospores, or sporangiospores, which are spores, are used in asexual reproduction.
- Vegetative reproduction occurs via Budding, Fission, and Fragmentation.
- Through Ascospores, Basidiospores, and Oospores, sexual reproduction takes place.
Below is a diagram which gives a detailed explanation of the reproduction process:
In the kingdom of fungi, the usual form of sexual reproduction is not always present. In some fungi, a diploid cell does not develop from the union of two haploid hyphae. In these circumstances, a transitional stage known as Dikaryophase manifests. The emergence of diploid cells comes after this phase.
Classification of Kingdom Fungi
Fungi can be classified into different types based on different characteristics. Based on feeding habits, they can be classified as Saprophytes, Parasites and Symbiotic Fungi. Based on their morphology of mycelium and the manner of the spore generation they are broadly categorised as Phycomycetes, Basidomycetes, Ascomycetes and Deuteromycetes.
A. Based on the morphology of the Mycelium and the manner of spore generation
Kingdom fungi is separated into numerous classes, which is illustrated in the given flow chart:
These are also known as lower true fungi. They are further divided into two types- Oomycetes and Zygomycetes.
- These are found as obligatory parasites on plants, decaying wood in moist environments, and in aquatic settings.
- The mycelium is coenocytic and aseptate.
- If the gametes have similar morphologies, they are known as Isogamous, and if they have different ones, they are known as Anisogamous. Asexual reproduction occurs through zoospores or aplanospores.
- Few examples are Rhizopus and Mucor. Phycomycetes are further classified into Oomycetes and Zygomycetes.
This class of fungus called Deuteromycetes encompasses all those fungi whose sexual stage is either unknown or nonexistent. Some of its characteristics are:
- The majority of deuteromycetes members may actually be ascomycetes, in which sexual reproduction is either absent or has not yet been identified.
- Some Deuteromycetes resemble yeast-like unicellular organisms.
- Conidia and other forms of spores frequently serve as the means of asexual reproduction.
- Typically, the mycelium is septate and branched.
- Most of the members are decomposers and some of them are parasites.
- There are no clamp connections, which are present in basidiomycetes.
Ascomycetes are considered a separate class of fungi based on their special reproductive structure called Asci. Some of its characteristics are:
- Ascomycetes are often referred to as sac-fungi.
- They are typically seen in multicellular form; unicellular form is uncommon.
- The mycelium of ascomycetes is branched and septate.
- They may be saprophytic, parasitic, decomposers, coprophilous, or any of these.
- Ascospore is the name for sexual spores. Conidiospores are used in asexual reproduction.
- Aspergillus, Claviceps, and Neurospora, for instance, are a few examples.
Basidiomycetes are often considered the most advanced and commonly encountered fungi due to their large and conspicuous fruiting bodies.Some of its characteristics are:
- These include mushrooms (gill fungi), toadstools, puffballs, and bracket fungi, among others.
- Mycelium is branched and septate.
- Vegetative reproduction via fragmentation occurs frequently.
- Plasmogamy occurs as a result of fusion of vegetative or somatic cells of two different strains. This results in the production of basidium.
- Four basidiospores are produced inside the basidium as a result of Karyogamy and Meiosis.
- The basidia get arranged in fruiting bodies called basidiocarps.
- Among the best wood decomposers are basidiomycetes. Basidiomycetes are able to outcompete most insects in the decay of hardwoods and woody tree parts. Basidiomycetes have the capacity to break down cellulose and lignin.
Based on the Mode of Nutrition
Fungi are classified into three types based on their mode of nutrition:
- Saprophytic Fungi- These fungi live and feed on dead organic matter. E.g. Penicillium, Rhizopus, Mucor.
- Parasitic Fungi –They feed on hosts, which are either living or dead organisms. By spreading disease, they cause harm to the hosts. The parasite-host relationship is referred to as parasitism.
- Symbiotic Fungi –Symbiotic fungi live in an interdependent relationship with other species that benefits both parties. Lichens and mycorrhiza are two examples. Lichens are the result of a mutualistic relationship between algae and fungi.In this case, algae and fungi benefit from each other because fungi provides shelter for algae and algae provides carbohydrates for fungi. Mycorrhiza is a symbiotic relationship that exists between fungi and plants.
FAQs on Fungi
1. Which organisms are included under Kingdom Fungi?
Fungi are organisms which are heterotrophic and eukaryotic in nature. Mucor, Rhizopus, Mushroom, Toadstools are all included under this kingdom.
2. How may Different Classes of Fungi are there in Kingdom fungi?
The fungi are divided into four main classes- Phycomycetes, Basidomycetes, Deuteromycetes and Ascomycetes.
3. Write the Importance of Kingdom Fungi.
Most of the fungi are decomposers and they help in the recycling of the mineral nutrients. Some of them are used in food and others are used in making antibiotics, which are medicines.
4. Who was responsible for the Discovery of Fungi?
Fungi were first found in 1858 by Heinrich Anton de Bary. The word ‘fungus’ comes from the Latin word ‘mushroom’.
5. Fungi were earlier classified into the Plant Kingdom based on which Feature?
Both plants and fungi have a cell wall, and hence they were initially placed under the plants, but then like plants they were unable to synthesise their own food.
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