Reproduction in Fungi (3 Types of Reproduction) | Mycology

In this article we will discuss about reproduction in fungi :- Vegetative reproduction in fungi, asexual reproduction in fungi and sexual reproduction in fungi

Reproduction in Fungi

• The production of new individuals from parent organisms is called Reproduction.
• Reproduction in fungi takes place by vegetative, asexual and sexual methods.

1. Vegetative Reproduction in Fungi

• A portion of body becomes separated off and gives rise to new individual is called vegetative reproduction
• In vegetative reproduction the union of mature sex cells or sex organs does not involve.
• The common method of vegetative reproduction are: Fragmentations, Fission and Budding

A. Fragmentation

• In this process, the mycelium breaks into two or more similar fragments either accidentally or due to some external force.
• Each fragment grows into a new mycelium.
• E.g., Aspergillus, Alternaria, Mucor and Rhizopus

B. Fission

• The parent cell splits into two equal halves.
• Each of these halves then develops into a new individual
• E.g., Yeast

C. Budding

• The parent cell produces one or more projections called buds.
• The bud detaches and grows into a new individual.
• E.g., Yeast, Ustilago

2. Asexual Reproduction in Fungi

• It is the type of reproduction, a special reproductive structures called spores or propagates are formed.
• About 20% fungi have only asexual reproduction.
• The fungal spores always result from mitosis and hence are described as mitospores.
• The different types of asexual spores in fungi are: Zoospores, Conidiophore, Chlamydospores, Oidia and Aplanospores

A. Zoospores

• They are flagellated, motile spores produced inside structures called zoosporangia.
• These spores do not have a cell wall.
• E.g., Achyla, Pythium, Phytophthora, Albugo

B. Conidiophore or Conidia

• These are non-motile spores produced singly or in chains at the tip of the hypha branches that are called conidiophores.
• E.g., Aspergillus and Penicillium.

C. Chlamydospores

• These are thick walled resting spores which arise directly from hyphal cells.
• They store reserve food.
• E.g., Ustilago

D. Oidia

• These are spore like structures formed by the breaking up of hypha cells.
• They do not store reserve food and hence cannot survive under unfavourable conditions.
• E.g., Collybia, Coprinus

E. Aplanospores

• These are non-motile, thick wall spores produced inside structures called sporangia.
• They are dispersed by wind or water currents.
• E.g., Mucor, Rhizopus and Pilobolus

3. Sexual Reproduction in Fungi

• Sexual reproduction occur in all groups of fungi except Dueteromycetes (Fungi imperfecti).
• Sexual reproduction is carried out by fusion of compatible nuclei of two parent cell.
• The process of sexual reproduction involves three phases:
  • Plasmogamy: fusion of protoplasm of two compatible haploid cells.
  • Karyogamy: fusion of the two haploid nuclei within the dikaryotic cell.
    • In Phycomycetes: Karyogamy just after plasmogamy
    • In Ascomycetes and Basidiomycetes: Karyogamy after some time.
  • Meiosis: The diploid zygote undergoes meiosis, a type of cell division that reduces chromosome number by half. This produces haploid spores, which can germinate to form new fungal hyphae.

Types of Plasmogamy

A. Planogametic Copulation

• This involves the fusion of two motile gametes or planogametes.
• types of Planogametic Copulation
• It is of tree types depending upon the nature and structure of the fusing gametes

1. Isogamy: Fusing gametes are morphologically similar but physiologically different. They are formed on different hyphae. E.g., Synchytrium, Catenaria
2. Anisogamy: Fusing gametes are morphologically as well as physiologically dissimilar. The male gamete is smaller and more active than female gamete. E.g., Allomyces
3. Oogamy: The female gamete or ovum or egg is non motile and male gamete or anthrozoid is motile. They are formed in specialized gametangia known as oogonium and antheridium respectively. E.g., Monoblipheris

B. Gametangial Contact

• Here, gamete bearing structures called gametangia come into close contact but do not fuse.
• Then, a fertilization tube forms into the female gametangia.
• The male nucleus migrates through this fertilization tube into the female gametangia.
• E.g., Albugo, Aspergillus, Phytophthora etc.

C. Gametangial Copulation

• This process involves fusion of the entire content of two compatible gametangia.
• The two compatible gametangia come in close contact, at the point of contact their walls dissolve and their contents mix.
• The two gametangia ultimately fuse and develop into a zygospore
• E.g., Mucor, Rhizopus

D. Spermatisation

• Sex organs are completely absent
• Tiny unicellular spore like structures called spermatia are formed.
• The spermatia are carried to the receptive hyphae (Carpogyne: female gamete) by air, water or insects and the spermatium enter the receptive hyphae through a pore.
• E.g., Puccinia

E. Somatogamy

• Sex organs are absent.
• The fusion occurs between two somatic cells of hyphae.
• E.g., Morchella, Agaricus, Peziza