There are different modes of reproduction in fungi such as sexual, asexual, and vegetative modes of reproduction. There are involve different methods in asexual mode, sexual mode, and vegetative mode of reproduction, each of these methods are discussed below;
Different modes of reproduction in fungi
Mainly there are three types of reproduction in fungi such as
- Vegetative Reproduction
- Asexual Reproduction
- Sexual Reproduction
Vegetative Reproduction of Fungi
The vegetative reproduction of fungi is accomplished in four distinct modes such as;
- Binary Fission
- Budding
- Fragmentation
- Spore formation (asexual reproduction0
Budding
- In the budding process, a small protuberance occurs at a portion of the mother cell.
- The protuberance started to grow and increases its size.
- At the same time, the parent nucleus is started to divide and one portion of the nucleus is passed into the bud and another one remains at the mother cell, that’s how the bud gets the nucleus of its parent cell.
- Now a septum is formed between the mother cell and bud, finally, the bud get separated from the parent cell and developed into a new individual daughter cell.
- Sometimes buds are remain attached with the mother cell and keep reproduce and form a branching appearance.
- The budding mode of reproduction is found in Yeast.
Binary Fission
- In this method first, the cell started to elongate and the nucleus divides into two new daughter nuclei.
- Now two daughter nuclei are separated and during this time the cytoplasmic cleavage occurs centripetally in the middle until the mother protoplasm is formed two new daughter protoplasm.
- A double cross wall is formed between the two daughter cells and they get separated.
- Saccharomyces pobbe and Psygosaccharomyces reproduced by binary fission method.
Fragmentation
- In this method, the hyphae of fungi are fragmented and each of these fragments gives rise to a new daughter cell.
Asexual Reproduction of Fungi
In this method, algae reproduce by the formation of different types of asexual spores, which are formed in large numbers. The main function of these spores is to disseminate the species.
Types of asexual reproduction in fungi
There are mainly five types of asexual spores that are produced by fungi such as;
- Sporangiosopres: These are the single-celled, formed within a specialized structure called sporangia, which is formed at the end of hyphae known as sporangiophores. There are two types of sporangiospores as motile and nonmotile. The motile spores contain flagella such as Zoospores. The nonmotile spores lack flagella such as aplanospores. Example: Rhizopus.
- Conidiospores or Conidia: These are formed at the tip or side of hyphae. There are two types of conidiospores such as microconidia and macroconidia. The microconidia are small and single-celled conidia. While the macroconidia are large and multicelled onidia. Example: Penicillium, Apergillus
- Oidia or arthrospores: These are single-celled spores. Oidia are developed by the disjoining of hyphal cells. Example: Trichosporium, Geotrichum, Coccididious imitis.
- Blastospores: Blastospores are mainly developed by the budding process. These are formed at the tip of hyphae. Some examples of Blastospores are ascomycetes, basidiomycetes, zygomycetes.
- Chlamydospores: These are thicked walled, single-celled spores which are mainly formed durign the adverse condition. These spores can resist adverse environmental conditions. Chlamydospores are developed when a hyphal cell or a portion of hyphae contracts, loses water, round up and gives rise to a thick-walled chalmydospore. In returning favourable consition the chlamydospores again form a new fungal cell. Some example of chlamydosores are ascomycetes, basidiomycetes, zygomycetes.
Sexual Reproduction of Fungi
The sexual mode of reproduction in fungi is accomplished by the fusion of two nuclei from two different parent cells. Sexual reproduction is accomplished in three distinct steps such as;
- Plasmogamy: It is the first step of sexual reproduction in fungi. This step begins with the joining of two cells and fusion of protoplasm.
- Karyogamy: In this step, two haploid nuclei of previously joined cells are fused and formed a diploid nucleus.
- Meiosis: Now, the diploid nucleus goes through the meiosis process and again reduces the number of chromosomes to the haploid number.
Reproductive structure of fungi
The sex organelles of fungi are known as gametangia or gametangium. The sex organs of fungi are known as gametangia or gametangium. They may develop from gametes or may carry instead one or more gamete nuclei. If the male and female gametangia are morphologically different, the male gametangium is known as the antheridium or antheridia, and the female gametangium is termed as the oogonium or oogonia.
Different Methods of Sexual reproduction
Fungi follow various methods by which compatible nuclei are brought together in plasmogamy such as;
- Gametic Copulation: In this method, the naked gamest are fused. Both or one of these gametes can be motile.
- Gamete-gametangial copulation: In this method, 2 gametangia come in close contact but don’t fuse. The male nucleus uses a fertilizer tube or pore through which it migrates within the female gametangium.
- Gametngial Copulation: In this method two gametangia or their protoplasts are fuses; rise to a new zygote and develop into a resting spore.
- Somatic copulation: In this method fusion occurs between somatic or vegetative cells.
- Spermatization: It is a union with a special male structure known as spermatium with a female structure. Later during the plasmogamy, the spermatium loads its content within the female structure.
Sexual Spores of Fungi
The sexual spores are formed due to the fusion of two nuclei and occur less frequently and also occur in fewer numbers as compared to asexual spores. There are several types of sexual spores such as;
Ascospores
Ascospores are single-celled and produced within a sac known as ascus or asci. Each ascus usually carries eight ascospores. Within the ascus the two nuclei are fuse and formed diploid zygote nuclei, which is then undergoes through the meiosis process immediately after fusion.
Next, four haploid nuclei are formed from the meiosis process, then, these are divide once more by mitosis to form eight ascospores.
Basidiospores
Basidiospores are single-celled and mainly occurs on a club-shaped structure known as a basidium.
In basidium, nuclear fusion and meiosis take place. Next, basidiospores are developed by exogenously at the end of the special outgrowths known as sterigmata. Mainly four spores are developed at the end of each sterigmatum. If meiosis is followed by a mitotic division then 8 basidial nuclei are developed.
Zygospores
These are large and thick-walled spores, which are mainly produced at the end of 2 sexually compatible hyphae or gametangia of certain fungi fuse together.
During the sexual reproduction with Mucor hiemalis, two sexually compatible mating types + and – come in contact with each other and formes zygospores.
Oospores
Oosores are formed within a female structure known as oogonium. The eggs or oospheres are fertilized by the male gametes developed within an antheridium which results in the formation of oorspores.
Important Notes
- Both asexual and sexual spores may be covered by an organized protective structure known as fruiting bodies.
- The asexual fruiting bodies are known as acervulus and pycnidium, while the sexual fruiting bodies are known as perithecium and apothecium.
