4. Classification of Basidiomycota
Order: Agaricales
Family :Agaricaceae
Genus: Agaricus,
Coprinus,
Lycoperdon
Family :Amanitaceae
Genus: Amanita
Family :Trichlomataceae
Genus: Armillaria
Family :Pleurotaceae
Genus: Pleurotus
Family :Pluteaceae
Genus: Volvariella
Family :Lyophyllaceae
Genus: Calocybe
7. General Characters of Basidiomycota
1. Commonly called as “Club Fungi”
2. Consists of Filamentous Fungi – Septate hyphae with
perforated “Dolipore septum” which allows cytoplasm to
flow freely between cells
3. Cell components are made up of Chitin and Glucan
4. Reproduce by both sexually and asexually
5. It possess mostly single club shaped basidium on which four
basidiospores are borne at the tips of minute stalks called
sterigmata
6. Actively discharged basidiospores – Ballistospores
7. Passively discharged basidiospores – Statismospores
8. Clamp connection
Basidium
Basidiospores
Sterigma
Basidium with
Basidiospores
9. • Primary Hyphae – develops from a germinating basidiospore. Nuclear status = n
• Secondary Hyphae – results from fusion of two primary hyphae. Yields n+n cell
that continues to grow as a n+n hyphae
• Tertiary hyphae – exactly the same as secondary hyphae, n+n. However, it has
thick walls that enable production of fleshy and wood sporophores
3 types of Hypha
10. • The word basidium literally means "little pedestal“
• A basidium is a microscopic spore-producing structure
found on the hymenophore of reproductive
bodies of basidiomycete fungi
• These bodies also called tertiary mycelia, which are highly
coiled versions of secondary mycelia
• A basidium usually bears four sexual spores
called basidiospores
• A partially grown basidium is known as a basidiole.
Basidium
Basidium with
Basidiospores
11. Holobasidium
• Holobasidium: a non-septate basidium; single-celled, typically
club-shaped, and bearing sterigmata (usually four)
• More or less clavate, with sterigmata that are fairly small in
proportion to the basidium
• Gilled mushrooms, boletes, polypore, chanterelles, tooth fungi
have this type of basidium, and are called Holobasidiomycetes
• Also called a homobasidium
Type of Basidium
12. • A phragmobasidium is a basidium divided into
separate cells following meiosis
• The basidium is separated by the elongated two or
four cells of septa.
• A basidium that is divided into more than one cell by
transverse or longitudinal setpa
• In cross-section the metabasidium appears as four
cells
• Jelly fungi and the rusts and smuts
Phragmobasidium
Type of Basidium
14. Dolipore Septum
a. Dolipore septa are specialized dividing walls between cells (septa)
b. Have a barrel-shaped swelling around their central pore, which is about 0.1–
0.2 µm wide/ typically capped at either end by specialized membranes,
called "parenthesomes“ or “pore caps”
c. All dolipore septa can allow cytoplasm, and sometimes mitochondria, to
flow through their pores those in monokaryotic hyphae have perforated
parenthesomes, which allow cell nuclei to flow through as well
d. The function of the dolipore septum is the repair of the damages in the
hyphal. The damage of the hyphae is mainly caused by the plugging of the
electron dense material in the septum of the hyphae. This is the rapid and
the frequent problem caused in the hyphae
The structure of Dolipore septum was first described by Royall Moore and James McAlear in 1962
Dolipore septum
17. • A clamp connection is a hook like structure
formed by growing hyphal cells of certain
fungi belonging to the class Basidiomycetes
• It ensures that each cell has a compatible pair
of nuclei
• It helps to create genetic variation in sexually
reproducing species
• Clamp connection is seen in all Basidiomycota
fungi but is rarely seen in Rust fungi
Clamp Connection
18. Steps in Clamp Connection
Terminal cell of hypha. Growth only takes place at hyphal tips
Hyphal tip elongating
Synchronous division of nuclei and the beginning of hyphal branch
that will become the clamp connection. Once nucleus migrates into
the new clamp
Septum forms at base of the clamp trapping nucleus. Two nuclei of
different strains migrate to the hyphal tip, while other nucleus
migrates away from the tip
Septum forms below clamp forming new cell at hyphl tip.
Fusion of the clamp to the adjacent cell releases nucleus of
different strain to the adjacent cell
Then, both the terminal and subterminal are binucleate, each
with a compatible pair of nuclei
19. • Fungal hyphae growth
Basidiomycota fungi consist of hyphae, which are
thread-like structures that make up the fungal body. The
first step in the formation of a clamp connection is the
growth of hyphae
• Formation of a septum
As the hyphae grow, they develop septa, which are
cross-walls that separate individual hyphal cells. The
septa have pores that allow cytoplasmic and organelle
movement between adjacent hyphal cells
Various Steps in Clamp Connection
20. • Initiation of nuclear division
Within a hyphal cell, nuclear division occurs. The nucleus
undergoes mitosis, resulting in the formation of two
daughter nuclei.
• Formation of a clamp connection
After nuclear division, a specialized structure called a
clamp connection is formed in Basidiomycota fungi. The
clamp connection develops at the base of the septum,
near the original nucleus
Various Steps in Clamp Connection
21. • Extension of the clamp connection
The clamp connection extends from the base of the
septum into the adjacent hyphal cell. It grows in a spiral-
like manner and forms a bridge connecting the two
hyphal cells
• Transfer of nuclei
Once the clamp connection is established, one of the
daughter nuclei from the original hyphal cell moves
through the clamp connection and enters the adjacent
hyphal cell. This process ensures that both hyphal cells
receive a complete set of nuclei
Various Steps in Clamp Connection
22. • Cell wall reinforcement
As the clamp connection matures, the cell walls
surrounding it undergo reinforcement. This reinforcement
helps stabilize the clamp connection and prevent its
breakage
• Continued growth and branching
With the successful formation of the clamp connection,
both hyphal cells continue to grow and branch,
contributing to the overall expansion and development of
the fungal mycelium.
Various Steps in Clamp Connection
23. • The life cycle of basidiomycetes has primary, secondary and tertiary mycelium.
• They produce both haploid and dikaryotic mycelia, with the dikaryotic phase
being dominant.
• They generally reproduce sexually by forming basidiospores on a basidium.
• In the basidium, nuclei of two different mating strains fuse (karyogamy), giving
rise to a diploid zygote that then undergoes meiosis.
• The haploid nuclei migrate into four different chambers appended to the
basidium, and then become basidiospores.
Life cycle of Basidiomycetes
25. • Each basidiospore germinates and generates monokaryotic haploid hyphae that is
called a primary mycelium.
• Mycelia of different mating strains combine to produce a secondary mycelium that
contains haploid nuclei of two different mating strains.
• This forms the dominant dikaryotic stage of the basidiomycete life cycle and each
cell in this mycelium has two haploid nuclei, which will not fuse until formation of
the basidium.
• Later, the secondary mycelium generates a basidiocarp (a fruiting body). The
basidiocarp bears the developing basidia on the gills under its cap.
Life cycle of Basidiomycetes
26. Sexual Reproduction of Basidiomycetes
1. Sexual reproduction in Basidiomycota takes place
in the fruiting body, in specialized structures called
basidia
2. The basidia is itself formed by plasmogamy
between mycelia from two different spores
3. Plasmogamy results in binucleate hyphae, that is,
hyphae with two types of nuclei, one from each
parent
4. In the gills of the fruiting body, some cells undergo
fusion of these two nuclei
5. Soon after fusion, meiosis takes place, resulting in
four haploid nuclei
6. The nuclei then migrate to the terminus of the
basidium and form four individual projections
7. These projections are then separated by cell walls
to become spores
27.
28.
29. • Basidiomycota reproduce asexually by either budding or
asexual spore formation
• Budding occurs when an outgrowth of the parent cell is
separated into a new cell. Any cell in the organism can bud.
• The septae of terminal cells become fully defined, dividing
a random number of nuclei into individual cells
• The cell walls then thicken into a protective coat. The
protected spores break off and are disbursed.
Vegetative Reproduction of Basidiomycetes
30. Asexual reproduction
It takes place by chlamydospores, that are formed rarely
during unfavourable condition.
Terminal or intercalary chlamydospores are developed on
dikaryotic mycelium, which on germination during favou-
rable condition produce dikaryotic mycelium.
31. Sexual spore- Basidiospores
1. A basidiospore is a reproductive spore produced
by Basidiomycete fungi
2. Basidiospores typically each contain one haploid
nucleus that is the product of meiosis, and they
are produced by specialized fungal cells
called basidia
3. Four basidiospores develop on appendages from
each basidium, of which two are of one strain and
the other two of its opposite strain
Basidiospores of Agaricus bisporus
