Ascomy cotina
Q.1. Describe different kinds of fruiting bodies found in Ascomycetes.
Related Question -
Q. What is Apothecium and Hysterothecium ? In Which group of fungi these are found ?
Ans. Types of fruiting bodies in Ascomycetes
After sexual reproduction, the vegetative hyphae surround the ascogonium and form a ball like thick walled structure known as “fruiting body or ascocarp.” The following types of ascocarps are found in the members of class Ascomycetes-
(1) Cleistothecium:-
The fruiting body or ascocarp of this type is round in shape as ball which is covered from all sides. It does not consist a pore and on decay of the wall of fruiting body ascorpores emerge out. Such type of fruiting body is found in Penicillium and Aspergillus.
( 2 ) Perithecium:-
The fruiting bodies of this type are hollow and having flask like structures. Many asci and paraphysis are attached to its based part hymenium. The fruiting body opens through a pore towards outside.
( 3 ) Apothecium:-
The fruiting body of this type is like a cup or a saucer. It is fleshy like leather. Fruiting body is of black brown colour. Its upper layer is known as hymenium which bears a number of asci and paraphysis, e.g., Peziza.
(4) Hysterothecium:-
Fruiting bodies of this type are small, fall and black coloured. These are tough and when mature they open by a slit.
Q.2. Write the difference between Ascomycetes and Basidiomycetes. (2006)
Ans. Difference between Ascomycetes and Basidiomycetes
Q.3. Differentiate between cleistothecium and apothecium. (2004,08)
Ans. Cleistothecium:-
This is a small hollow, more or less globose, indehiscent ascocarp without an opening. The fruit wall which is called the peridium may simply consist of loosely interwoven hyphae or pseudoparenchyma. It may be smooth but usually it is covered with hyphal outgrowths called the appendages (a) which may be of several types. The globose or ellipsoidal asci lie scattered at different level within the peridium (b) In some they are arranged regularly and form distinct hymenium ( c ) The ascospores escape by the decay or irregular splitting of the wall of the asci and the cleistothecium.
Apothecium:-
The typical apothecium is characteristic of the advanced members of higher Ascomycetes. It is a dise or saucer - shaped or even a cup - like structure. In size it usually varies from a few millimetres upto several centimeters in diameter. It varies in colour from pale brown to black sometimes red, orange, yellow or even colourless. The apothecium in some species is elevated on a distinct stalk and is sessile in others.
Q.4. Write short note on brachymeiosis. (2006, 08)
Ans. As a result of fertilization, pairs of male and female nuclei are formed in ascogonium. After this, setpa are formed in ascogonium due to which many cells are formed and each cell contains a pair of both the nuclei. From this type of cell, multicellular ascogenous hypho is formed in each cell of the hypha a pair of nuclei is present. The apical cell of ascogenous hypha turns to form a hook like structure called crozier.
Both the nuclei in crozier undergo conjugate division to form 4 daughter nuclei followed by the formation of septa resulting into the formation of terminal cell, penultimate cell and basal cell. Two daughter nuclei are present in penultimate cell while terminal cell and basal cell contain one nucleus each. After this, the two nuclei of penultimate cell fuse together to form diploid nucleus and this cell functions as ascus mother cell from which ascus is formed. In diploid nucleus of ascus, one meiotic and one mitotic division take place as a result of which 8 haploid nuclei and formed which in turn forms 8 ascospores. In the formation of ascospores in the ascus, this type of nuclear division is known as Brachymeiosis.
Q.5. Discuss the general characters and classification of class Deuteromycets. (2011)
Ans. General Characters: -
1. The class Deuteromycetes or Fungi Imperfecti includes those group of fungi which perfectly lack sexual reproductive organs and sexual stages.
2. The members of this class mostly resemble to Ascomycets and Basidiomycetes in structure and reproduction.
3. The fungi of this class cause many important plant disease which cause sufficient damage to the crops.
4. The vegetative mycelium is ectophytic, inter or intracellular,branched, hyaline or brown, septate and reticulate.
5. Asexual reproduction takes place by means of conidia, chalamydospore
6. Asexual reproduction is completely absent.
Classification
Class - Deuteromycets
