Classification of fungi
A number of criteria are used for classifying fungi morphology of mycellum , mode of spore formation and fruiting bodies form the basis of the classification of the kingdom. A common systematic presentation is given below :
- Oomycetes : The algal fungi
- Hyphal wall contains cellulose and other glucans in many members.
- The mycellum is coenocytic (multinucleate and aseptate)
- Asexual reproduction involves the formation of spore containing sacs or sporangia. In aquatic forms, the sporangia produce zoospores.
- Zoospores generally have two laterally inserted flagella with heterokont condition, in which one flagellum is smooth (whiplash) while the other is of tinsel type )having the surface outgrowths called mastigonemes).
- Sexual reproduction is by planogametic fusion or gametangial contact.
- The product of sexual reproduction and site of meiosis is oospore.
- Zygomycetes : The conjugation fungi
- It is class of terrestrial fungi which are mostly saprotrophic and rarely parasitic.
- Hyphal wall contains chitin or fungal cellulose.
- The mycelium is coenocytic (multinucleate, aseptate) like the one found in Oomycetes.
- motile cells(zoospores or planogametes) are absent.
- Mitospores are non motile. They are called sporangiospores as the spores are formed inside sporangia that are borne at the tips of special hyphae called sporangiophores.
- Sexual reproduction occurs through gametangial copulation or conjugation. Because of it, zygomycetes are also called conjugation fungi.
- the gametes are commonly multinucleate and are called coenogametes.
8.Sexual reproduction produces a resting diploid spore called zygospore. Because of the presence of zygospore, the group of fungi is called zygomycetes. Zygospore differs from oospore in that , for its formation a distinct food laden, non motile, large female gamete is not produced.
- Zygospore is the site of meiosis and does not give rise to new mycelium directly. Instead it produces a new sporangium called germ sporangium (previously called zygosporangium). Germ sporangium forms meiospores called germ spores.
- Sometimes, gametangia fail to fuse. Gametangia become surrounded by a thick wall resulting in formation of azygospore(parthenogenetically produced zygospore).