CLASSIFICATION OF FUNGI OR FUNCTIONING OF FUNGI
We are going to discuss the fungus / fungi classification do you really know about the classification of fungi? so, if don’t know let’s do read with us.. to know about the classification of fungus or fungi.
Various classifications of fungi have been given by different scientists. One of them, which is the most practical, has been briefly described below. In this system fungi have been classified into five classes on the basis of thallus structure and types of sexual reproduction.
Class 1. Myxomycetes. These fungi are also known as slime molds. The body (thallus) consists of a multinucleate structure called plasmodium.
They do not have a definite cell wall and instead The outer protoplast (ectoplasm) is thick and tough. Thus the thallus resembles amoeba, hence, these fungi are also termed as myxamoeba. Like amoeba they move by means of pseudopodia. These are holocarpic. Asexual reproduction takes place by fission and cysts. During sexual reproduction haploid spores are formed. The sporangium has a characteristic network of protoplasmic threads, called capillitium. Gametes are biflagellate and the sexual reproduction is isogamous. Examples: Physarun, Reticularia, etc.
Class 2. Phycomycetes. The thallus of these fungi is non-mycelial or aseptate, filamentous and coenocytic. Many of the hyphae Phycomycetes are aquatic, hence these fungi are also known as algal fungi. Aquatic members are isogamous, anisogamous 0gamous but Or terrestrial members are mostly isogamous with non-motile gametes.
The class Phycomycetes has been further classified into the following three sub-classes.
Sub-class 1. Archimycetes. Thallus consists of a large single cell and mycelium is absent.
Examples: Synchytrium, Protomyces.
Sub-class 2. Oomycetes. Mycelium is well developed. Sexual reproduction is by gametic
contact or gametic copulation. Gametic fusion results in the formation of oospore.
Examples: Saprolegnia,Pythium
Sub-class 3. Zygomycetes. Mycelium is well developed; sexual reproduction is by gametangial
copulation.
Examples: Mucor, Rhizopus.
Class 3. Ascomycetes. These are also known as sac fungi. Thallus is non-mycelial (e.g. Saccharomyces) or profusely branched septate mycelium (e.g., Aspergillus, Penicillium). Asexual reproduction occurs by means of conidia or budding. Sexual reproduction takes place by means of antheridia and ascogonia and their fusion results in the formation asci (sing. = ascus). The asci are formed endogenously within a fruiting body called ascocarp. Each ascus has eight ascospores. The ascospores on germination give rise to haploid mycelium.
The class Ascomycetes has further classes. classified into two sub- classes
Sub class 1. Hemiascomycetes: Ascogenous hyphae and ascocarp are absent.
Example: Saccharomyces.
Sub class 2. Euascomycetes: Ascogenous hyphae and ascocarp are present.
Example: Morchella.
Class 4. Basidiomycetes. These are also known as club fungi. Mycelium is septate and uni-, bi-, or multinucleate. Asexual reproduction takes place by budding and conidia but no special Sex organs are formed. Sexual reproduction takes place by conjugation of hyphae of two different strains, resulting in the formation of dikaryotic hyphae. Two nuclei of one of the dikaryotic cells fuse to form diploid nucleus (this cell is now called basidium) which after meiosis exogenously forms four haploid basidiospores. Thus basidium always has definite number of (i.e., four) basidiospores
The Class Basidiomycetes has been classified into two subclasses:
Sub -class 1. Holobasidiomycetes: Basidium is not septate (called holobasidium).
Example: Agaricus.
Sub class 2. Heterobasidiomycetes: Basidium septate and deeply divided (called phragmobasidium).
Examples: Ustilago, Puccinia.
Class 5. Deuteromycetes. This class is also known as Fungi imperfecti. Mycelium is septate and well branched. The class includes fungi in which stages of sexual reproduction are absent and reproduction occurs by asxeual methods only. Some of the asexual structures are synnema,pycnidia, acervuli, sporodochium, etc.
Examples: Alternaria, Helminthosporium, Colletotrichum, etc.
Habitat
Saccharomyces is a saprophytic fungus that grows rapidly in media containing sugar, such as sugar- cane juice, date palm, grapes, etc. lt also occurs in the nectariferous glands of flowers, ripe and decaying fruits and fermented food material. In fact, name Saccharomyces comes from its great affinity to the medium containing sugar (Saccharin = sugar, Oomycetes = fungi, i.e., sugar containing fungi or Saccharomyces)