2. GENERAL CHARACTERISTICS
1. 3200 Described species
2. 3400 genera
3. Totel no. of species factor : 10-20 or even more
4. Sac fungi
5. Mycelium is septated and branched except in Yeast.
6. Meaning : Askos (a leather bottle, bag or bladder) and Myces (a fungi).
7. Sexually produces spores called ascospores.
8. Ascospores are contained within a sac, the ascus.
9. The ascus contains 8 ascospores.
10. The ascomycetes are recognized by fruiting bodies or ascocarp.
11. The ascocarp surround the asci.
12. Saprotrophs
13. Biotrophic parasites of plants and animals including humans.
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3. CON…
• 14. Many ascomycete grow as endophytes. 28.Agent of histoplasmosis
• 15. Some are mutualistic symbionts. E.g. Lichen.
• 17.Grow in soil, above-ground parts of plants, found in freshwater and in the sea.
• 18. Asexual reproduction is by non-motile conidia.
• 19. Diverse phylum
• 20. Complete absence of flagellated cells.
• 21. Cell wall contain large amount of chitin and less cellulose
• 22. Heterothallic or homothallic
• 23. Cross walls in the spores sometimes.
• 24. Septa have pores that allow migration of cytoplasm organelles and nuclei.
• 25. Plasmogamy is separated from karyogamy produces dikaryotic phase.
• 26. Ascomycota and Basidiomycota are sister groups but no indication of ancestors.
• 27. Having ability of cytoplasmic fusion of vegetative hyphae (anastomosis).
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6. CLEISTOTHECIUM
1. Cleistothecium completely enclosed the asci which are formed throughout the ascocarp.
2. There is no opening.
3. Their shapes are globose,spherical and club.
4. The ascomatal wall is called peridium and typically consists of densely interwoven hyphae
or pseudo parenchyma cells.
5. It may be covered with hyphal outgrowth called appendages.
6. Spores are released only by decay or disintegration.
7. Asci are in scattered form.
8. Examples of cleistothecium are powdery mildews, Aspergillus and penicillium.
9. In powdery mildews It is called as chasmothecium.
10. Cleistothecia are small, pinhead-sized, spherical structures that are initially white and later
turn black with age.
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8. PERITHECIUM
1. Perithecium belong to class Pyrenomycetes (e.g. Sphaeriales and Hypocreales).
2. It is flasked-shaped fruiting body opening by a pore or ostiole.
3. The perithecial wall or peridium is formed from sterile flattened cells derived from
hyphae which surrounded the ascogonium during development.
4. Perithecia are often single as well as in some genera they are embedded in a mass
of tissue forming a perithecial stroma.
5. The layer of asci at the base.
6. Centrum is the central part where asci develop.
7. The perithecial wall composed of pseudo parenchyma tissues.
8. Examples of perithecium are Sordaria and Neurospora.
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10. APOTHECIUM
1. An apothecium (plural: apothecia) is a wide, open, saucer-shaped or cup-
shaped fruit body.
2. It is sessile and fleshy.
3. The structure of the apothecium chiefly consists of three
parts: hymenium (upper concave surface), hypothecium,
and excipulum (the "foot").
4. The asci are present in the hymenium layer.
5. The asci are freely exposed at maturity.
6. The fertile layer is free, so that many spores can be dispersed
simultaneously.
7. Examples are morel and Morchella.
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12. GYMNOTHECIUM
1. In Gymnothecium there is a loose open network of peridia forming a
gymnothecium and the asci can be seen through the network.
2. Peridial hyphae extend as hooked hairs.
3. The peridial wall of a gymnothecium consists of a loosely woven
"tuft" of hyphae, often ornamented with elaborate coils or spines.
4. A gymnothecium is a completely enclosed structure containing
globose or pear-shaped, deliquescent asci.
5. Examples are the Gymnoascus, Talaromyces and Arthroderma.
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14. PSEUDOTHECIUM
1. Pseudothecium ascocarp resembling a perithecium but whose asci are
not regularly organised into a hymenium and are bitunicate, having a
double wall which expands when it takes up water and shoots the
enclosed spores out suddenly to disperse them.
2. It is not a true fruiting body.
3. The asci are formed within locules in a pseudoparenchymatous
ascostroma.
4. There is no periderm.
5. Examples are Pleospora infectoria and Venturia inaqualis.
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16. ASEXUAL SPORES OR CONDIA OF ASCOMYCOTA
Arthroconidia Microsporum Proconidia
Blastic
conidium
Thallic type
conidium
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17. ARTHROCONIDIA
• They are typically formed as chains of conidia alternating with secrete
cells.
• An arthroconidium becomes released when the neighbouring cells
disintegrate.
• Arthroconidia are a type of fungal spore typically produced by
segmentation of pre-existing fungal hyphae.
• Geotrichum has septate mycelia which readily fragment into arthrospores
which are the organism's primary means of reproduction.
• Example of athroconidia is plectomycetes.
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19. MICROSPORUM
• The spores are multicellular and thick walled with granular external ornamentation.
• Microsporum forms both macroconidia (large asexual reproductive structures)
and microconidia (smaller asexual reproductive structures) on short conidiophores.
• Macroconidia are hyaline, multiseptate, variable in form, fusiform and spindle-shaped
to obovate.
• Macroconidia is 7–20 by 30–160 um in size, with thin or thick echinulate to
verrucose cell walls.
• Their shape, size and cell wall features are important characteristics for species
identification.
• Microconidia are hyaline, single-celled, pyriform to clavate, smooth-walled, 2.5–3.5 by
4–7 um in size and are not diagnostic for any one species.
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21. PROCONIDIA
• When upright branches develop which instead of elongation undergo
repeated division forms cells which are separated from each other by
incomplete septa these cells are termed as proconidia.
• Proconidia continue to bud apically forming macroconidia.
• Example of proconidium is Neurospora crassa.
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23. BLASTIC CONIDIUM
1. It develops by budding or swelling process.
2. The conidia develops by the blowing out of the wall of a cell usually from the tip
of hypha.
3. The cell wall of this cell is locally weakened and the developing conidium bulges
out and is delineated by a septum.
4. Yeast is an example of blastic conidium.
5. The general name for spores formed this way is blastospores.
6. When expansion of a cell includes the complete cell wall of the conidiogenous
cell, this is known as holoblastic conidium formation.
7. In the case of enteroblastic conidium formation, the cell wall of the
conidiogenous cell is disrupted and the conidium appears through an opening in
the cell wall.
8. The formation of the conidial chain in the genus Aspergillus is an example of
enteroblastic conidiogenesis.
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25. THALLIC TYPE CONIDIUM
1. It is formed by conversion of pre-existing hyphal elements in which
terminal cells of hypha cut off by septa.
2. If the whole cell is converted into a conidium, this is called holothallic.
3. Holothallic-derived conidia usually have thick, melanized, and often
encapsulated cell walls.
4. These conidia are, in general, referred to as chlamydospores.
5. Thallic conidiogenesis can also result in fragmentation of a cell into
conidia, the so-called thallic–arthric mode that gives rise to
arthrospores
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