Fungi are unique in lifestyles and genetic makeup within this diverse kingdom of organisms. As expected, their reproduction is also complex. Fungi usually reproduce both sexually and asexually.
Most fungi reproduce by forming spores. These spores are very tolerant to extreme conditions such as cold and lack of water. Spores can be formed both by sexual meiotic and asexual mitotic reproduction processes. These are called meiospores and mitospores respectively. This also depends on the species and conditions. Also, most fungi life cycles include both diploid and haploid stages.
Fungal sexual reproduction is not the same as sexual reproduction in animals or plants. They have morphological differences in sexual structures and reproductive strategies. Accordingly, they are grouped.
At the beginning of sexual reproduction, the haploid hyphae from two fungal organisms meet and fuse, forming an interconnected network called anastomosis. The nuclei, however, remain separate. Such a hyphae with two distinct nuclei, is called a dikaryon . The dikaryon give rise to the sexual sporangia, or spore cases, where the nuclei fuse into one. Thereafter, the cell undergoes meiosis. Haploid spores are formed and the cycle is repeated.
In some fungi there are no diploid phase except for the sexual sporangium. In others, there is a complete loss in the ability of sexual reproduction.
Now, there are some fungi which reproduce by asexual fission or by fragmentation. Here, each fragment forms a separate organism.
Asexual reproduction can occur in either of the following two ways:
- with vegetative spores
- through mycelia fragmentation
In mycelia fragmentation, the fungal mycelium separates into pieces and each piece then grows into a separate mycelium. An observable sexual cycle is not present in fungi imperfecti and deuteromycota.
While yeasts can produce spores, they usually multiply as single cells that divide by budding. Most yeasts form definitive structures called asci. Each ascus contain up to eight haploid ascospores. Each of these fuse with adjoining haploids and multiply.
- McConnaughey, M. (2014). Physical Chemical Properties of Fungi☆. Reference Module in Biomedical Sciences. doi:10.1016/b978-0-12-801238-3.05231-4