Agaricus is a genus of mushrooms containing both edible and poisonous species, with possibly over 300 members worldwide. The genus includes the common ("button") mushroom (Agaricus bisporus) and the field mushroom (A. campestris), the dominant cultivated mushrooms of the West.
2. Habit & Habitat
Species of Agaricus
Structure of Agaricus
Reproduction in Agaricus
1. Vegetative Reproduction
2. Asexual Reproduction
3. Sexual Reproduction
Conclusion
References
Synopsis
3. Habit and Habitat
• Agaricus is an edible fungus and is
commonly known as mushroom.
• It is a saprophytic fungus found growing
on soil humus, decaying litter on forest
floors, in the fields and lawns, wood logs
and manure piles.
• It grows best in moist and shady places
and is commonly seen during rainy
season.
• It is cosmopolitan in distribution.
4. Species of Agaricus
• About 25 species of Agaricus have been reported from India.
It is commonly known as kukurmutta in U.P. and
dhingri in Punjab.
• A. campestris (field mushroom),
• A. bisporus (A. brunnescence; white mushroom) are
common edible mushrooms.
• A. bisporus (cultivated mushroom) is widely cultivated for
food purposes in Solan (Himachal Pradesh).
– Some species of Agaricus are poisonous (e.g., A.
xanthoderma) and some species may cause
gastrointestinal disturbances in some persons (e.g., A.
placomyces, A. silvaticus).
5. Structure of Agaricus
It can be studied in two
parts:
(a).Vegetative mycelium (living
inside the soil) Rhizomorph
(b).Fruiting body or
basidiocarp (present above
the soil and edible in young
stage)
7. (a) Vegetative Structure
• Vegetative mycelium is of three
types:
• Primary Mycelium:
• It originates by the germination of
uninucleate basidiospores carrying
either ‘+’ or ‘-‘ strain. The cells are
uninucleate i.e., monokaryotic. It is
short lived and becomes bi-nucleate
by fusing of two compatible hyphae
(Fig. 1 A).
8. Secondary Mycelium:
• It originates from primary mycelium. After fusion of the
hyphae of two opposite strains, the nucleus from one hypha
migrates to the other and later gives rise to the bi-nucleate
secondary mycelium i.e., dikaryotic. It is long lived and
abundant .
Tertiary Mycelium:
• The secondary mycelium grows extensively under the soil and
becomes organised into special tissue to form the fruiting
body or basidiocarp
• The fruiting body appears like umbrella above ground. It
is made up of dikaryotic hyphae. These hyphae are
called tertiary mycelium. The mycelium is
subterranean. The hyphae are septate and
branched.
9. Fairy Rings of Agaricus
• The mycelium of the Agaricus is subterranean. It has a
tendency to grow in all directions from a central point
to form a large invisible circular colony. The mycelium
also increases in diameter year after year and the being
at all times on the outer edge, because the central
mycelium dies away with age.
• These circles of mushrooms are commonly called “fairy
rings”, because of an old superstition that the
mushroom growing in a ring indicates the path of
dancing fairies.
10. (b).Structure & Anatomy of Basidiocarp
The mature fruiting body can be differentiated into
three parts
1.Stipe
2.Pileus
3.Annulus
11. 1. Stipe:
It is the basal part of the basidiocarp. In this region the
hyphae run longitudinally parallel to each other. A transverse
section of stipe shows that it is made up of two kinds of tissue,
i.e., (a) Compactly arranged hypahe in the peripheral region
known as cortex, (b) loosely arranged hyphae (with inter
spaces), in the central region known as medulla .
12. 2. Pileus
• The stipe at its top supports a broad umbrella shaped cap
called pileus.
• The mature pileus is 5 to 12.5 cm in diameter. From the
underside of the pileus hang approximately 300 to 600 strips
or plates of tissues known as gills or lamellae.
• The gills are white or pinkish in young condition and
turns brown or purplish black at maturity.
13. Transverse Section of The Gill
1. Trama:
It is the middle part of the gill. It is made up of
loosely arranged interwoven mass of
plectenchymatous tissue of long, slender hyphae.
These hyphae run, more or less, longitudinally.
2. Sub-Hymenium or Hypothecium:
The hyphae of the trama region curve outwards
towards each surface of the gill. They end in small
diametric cells forming a compact layer known as
sub-hymenium.
14. Transverse Section of The Gill
3. Hymenium or Thecium:
It is the outermost layer and lies on the surface of sub-hymenium
covering both sides of the gill. Some branches emerge out almost
at right angle to the sub-hymenium and develop a palisade like
layer consisting of basidia (fertile) and the paraphyses (sterile)
(Fig. 7A). Some of the sterile cells become enlarged and project
beyond the basidial layer. They are called as cystidia.
17. 1.Vegetative Reproduction:
It reproduces vegetatively by the mycelium in the soil & the
broken parts of it are capable of reproducing the fungus.
2. Asexual Reproduction:
(a). Chlamydospores are produced which are lateral or
intercalary in position. On germination, it gives rise to
hyphae.
(b). Oidia/Conidia may also be formed
under certain conditions which are also
known to have sexual function in the
diplodisation.
18. 3. Sexual Reproduction
The sexual reproduction is mainly somatogamous or
pseudogamous. The sex organs are completely absent and
their function has been taken over by the somatic hyphae which
are heterothallic.
However, a few species of Agaricus, like A. campestris A.
bisporus, are homothallic.
(a) Plasmogamy
(b) Karyogamy
19. Plasmogamy
• It is the first step in the sexual reproduction of
Agaricus. The vegetative hyphae with
uninucleate haploid cells from mycelia of
opposite strains (heterothallic) or from the
same mycelium (homothallic) come into
contact and fuse. Each of such fusion results
into a bi-nucleate (dikaryotic) cell. The
dikaryotic cell, by successive divisions, gives
rise to the bi-nucleate or dikaryotic mycelium.
This dikaryotic mycelium is perennial and
produces the characteristic fruiting body of the
mushroom year after year.
20. Karyogamy
• This is the second step in sexual reproduction.
This step is considerably delayed and takes place
in the young basidium. In it the fusion of the two
nuclei of dikaryon takes place
Meiosis:
• It is the third and last step in sexual reproduction.
It takes place in basidium prior to basidiospores
formation. Karyogamy is immediately followed by
meiosis. Thus, the basidiospores, formed after
meiosis, are haploid.
22. Conclusion
The extracts of the tested Agaricus species are a
promising source of antioxidant, antimicrobial,
and antiquorum sensing compounds and is
proved to be healthy foods. Regarding the
antibacterial and antifungal potential, the
ethanolic extracts were more effective than the
methanolic ones.
23. References
• General Microbiology by R.P. Singh
• Microbiology by Dubey & Maheshwari
• Botany by Y.D. Tyagi
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