Many systems of classification of fungi have been proposed from time to time by various mycologists. In more recent systems of classification of fungi, besides morphological criteria, host specialization, physiological, cytological, genetically, serological and biochemical characters are also taken into consideration. More than 100,000 recognized species of fungi are usually included into four main groups, those are:
Classification of Fungi: ZYGOMYCOTINA
These types of fungi occupy terrestrial habitat, invading the soil or decaying organic matter. They usually produce
asexual spores at the tips of specialized sporangiophores that extend into the air. These spores are carried by the wind to new territory. Mucor and Rhizopus are two important members of this group.
Rhizopus, a very common saprotroph, grows on a wide variety of organic substrates like bread, jellies, syrups, leather, etc. Rhizopus stolonifer, commonly known as bread mould, is the most widely known species. It may also grow on apples and other fruits in storage, causing soft rot. Some species of Rhizopus cause 'mucormycosis' in domestic animals and still others attack the nervous system in human beings with deadly significances. The mycelium, which appears as white cottony growth, is coenocyte and profusely branched.
Classification of Fungi: ASCOMYCOTINA
The largest group of higher fungi is Ascomycotina, represented by more than 30,000 species. They are popularly known as sac-fungi. This group of fungi is relatively advanced, showing more complexity than Zygomycotina, especially in sexual characters. The members of this group are mostly terrestrial saprophytes or parasites. Yeasts, black or green molds, powdery mildews, cup fungi, morels and truffles are some common examples of this group. Yeasts like Saccharomyces cerevisiae are economically important in the preparing and baking industries. Several species are the source of the antibiotic penicillin, the first 'wonder drug' of the world, whereas others help in ripening of cheese to impart distinctive flavours. Several species of Aspergillus are used in various industries, especially in the production of organic acids, enzymes, fats, vitamins and antibiotics. On the other hand, several parasitic species of the group Qausa destructive diseases in plants such as ear rot, foot rot, brown rot, leaf curl arid powdery fungus. Asexual reproduction usually takes place by means of conidia, formed at the tips of special hyphae called conidiophores. The conidia may have characteristic colors which give the fungi their typical appearance.
Classification of Fungi: BASIDIOMYCOTINA
Basidiomycotina are commonly known as the club fungi, comprises over 25,000 species of higher fungi. Puccinia (rusts) and (Usfitagty (smuts) are two important parasitic fungi of this group which are accountable for destructive diseases in cereals, causing enormous economic losses. Saprophytic members of this group are popularly known as rnushroorns, puff balls, pore fungi, toad stools, stinkhorns, bird's nest fungi, bracket fungi, etc. Several species of saproghytic basidiomycetes are liable for the destruction of valuable timbers. Some mushrooms produce mycotoxins which cause diarrhea and vomiting in earlier stages, but in later stages they cause liver damage, kidney failure and complete blackout, and even death may take place.
Classification of Fungi: DEUTEROMYCOTINA
Deuteromycotina comprise all forms of those fungi in which a sexual cycle has not been discovered! It is a purely artificial assemblage of fungal species, waiting to be included in appropriate classes after the discovery of their perfect (sexual) stages. The members of this group are saprophytes or parasites. The parasitic species cause early blight and tikka diseases in plants, and athlete’s foot, several skin diseases and pulmonary infection in animals. The mycelium is well developed and profusely branched with perforated septa. The hyphae may be inter-or intracellular and the cells are multinucleate.