ASCOBOLUS

CLASSIFICATION OF ASCOBOLUS

Kingdom :- Mycota

Division :- Eumycota

Sub-division :- Ascomycotina

Class :- Discomycetes

Order :- Pezizales

Family :- Pezizaceae

Genus :- Ascobolus

Ascobolus are seen growing on dung and on decaying wood, in damp places in rainy season.

STUDY OF VEGETATIVE STRUCTURE​

• The fungus mostly grows on the dung of herbivores and is called coprophilous. A few species (A. carbonarius) grow on burnt soils. 
• The thallus is made of richly branched mycelium that forms a complex structure and finally a cup shaped structure.
• The hyphal masses penetrate the substratum. These act as organs of absorption for the aerial branches. 
• The hyphae are branched and septate. Each cell is multinucleate.

SEXUAL REPRODUCTIVE STRUCTURES​

• The male reproductive organs are antheridia and the female reproductive organs are called ascogonia. 
• Antheridia and ascogonia are borne at the tips of separate branches. 
• Antheridium is borne at the tip of antheridial branch. It is cylindrical or clavate in shape. 
• Each antheridium is multinucleate.
• Ascogonium is also present at the tip of the ascogonial branch. It is sub-globose in shape and is multinucleate.
• The tip of ascogonium is drawn into a long and terminal organ called trichogyne. It reaches the tip of an antheridium.

ASCOCARP, ASCI AND ASCOSPORES​

• The ascocarps are apothecia and develop as a result of fertilization. 
• These are yellowish and saucer shaped. 
• Apothecium is a cup-shaped structure that is made of mycelium.
• The section shows three zones-the outermost called hymenium, the middle called sub-hymenium and the lowermost called hypothecium. 
• The lowermost hypothecium, is made of sterile hyphae, loosely packed to form pseudoparenchymatous region called trama. 
• The middle zone consist of a few erect hyphae. ‘This later merges with hymenial layer which is called sub-hymenium. 
• The hymenium consists of asci intermingled with paraphyses. 
• The asci elongate on maturation to protrude above the hymenial surface. These are found mixed with paraphyses. Ascus is a long and cylindrical structure. It opens by a terminal pore called operculum.
• Each ascus contains eight ascospores. Ascospore is one celled, large in diameter, purple or dark brown and the spore wall shows longitudinal colourless striations.

IDENTIFICATION

• KINGDOM – Mycota
  1. Chlorophyll absent
  2. Reserve food glycogen
  3. Cell wall of fungal cellulose.
• DIVISION – Eumycota
  1. A definite cell wall present.
• SUB-DIVISION :- Ascomycotina
  1. Mycelium septate.
  2. Spores borne endogenously in the ascus.
  3. Spores in definite numbers, in multiples of two, usually eight.
• CLASS :- Discomycetes
  1. Ascocarp, an apothecium.
• ORDER – Pezizales
  1. Apothecia fleshy or leathery.
  2. Apothecia usually not in stroma.
• FAMILY – Pezizaceae
  1. Apothecia cup-shaped or discoid.
  2. apothecia not differentiated into stipe and pileus.
• GENUS – Ascobolus
  1.  Apothecia upto 5 mm in diameter.
  2. Apothecia saucer-shaped and growing on dung.

REFERENCES

• https://en.wikipedia.org/wiki/Ascobolus
• https://www.shutterstock.com/search/ascobolus