Basidiomycota is a phylum of fungi, known as 'club fungi', that produces basidiospores on club-shaped cells called basidia, with members including mushrooms, puffballs, and bracket fungi. They can be either homothallic or heterothallic concerning mating systems, affecting their reproductive strategies and genetic variation. The life cycle involves complex stages including dikaryotic mycelium formation and the development of basidiocarps, with various classes demonstrating unique characteristics such as jelly fungi and puffballs.

1. Basidiomycota
Mushrooms, bracket fungi, puffballs,
rusts and smuts

2. • Phylum : Basidiomycota
• Is one of two large phyla that, together with the
Ascomycota, constitute the subkingdom Dikarya
(often referred to as the "higher fungi") within the
kingdom Fungi.Its name comes from producing
basidiospore. It is often referred to as " club fungi",
all members of this Phylum form spores on club-
shaped cells known as basidia. Mushrooms are the
most common examples of the members

3. • Characteristic of Basidiomycota :-
Basidiomycota are filamentous fungi
composed of septated hyphae (except for
yeasts) are unicellular.
Heterotrophic saprobes – cells of hyphae
secrete digestive enzymes and absorb
products of digestion
Include these groups: mushrooms, puffballs,
stinkhorns, bracket fungi, earth stars others
cause diseases for human like yeast
Cryptococcus and parasite on plants , rusts
disease , smuts disease many species eaten
are poisonous or semi-poisonous species.

4. Fig. 31-18
Shelf fungi, important
decomposers of wood
Maiden veil fungus
(Dictyphora), a
fungus with an
odor like rotting
meat
Puffballs emitting
spores

6.  The cell walls of the hyphae are variably composed of chitin
and β-glucans.
 Almost all its individuals are terrestrial , parasitic or
saprophytic
 The fungi of this group are characterized by the production of
spores known as basidiospores resulting from karyogamy and
meiosis, and are borne externally on slender protuberances,
the sterigmata (sing, sterigma). The sterigmata are developed
from a more or less club-like structure, called a basidium (pl.
basidia) for which the Basidiomycetes have been frequently
named as club fungi.

7. Unicellular basidium, with four sterigmata and
basidiospores.
Reproducing A sexually by budding , fragmentation of
hyphae to form Arthrospores(arthrospore.

8. Hyphae
• Hyphae are regularly
septate
• Specialized type of pore
can occur – dolipore
septum with
parenthosome
• Allows cytoplasmic
movement but prevents
nuclear migration from
one compartment to the
next

9. Mating Systems of Basidiomycetes:
About 10 per cent, of Basidiomycetes are homothallic.
Three types of homothallic behaviour may be distinguished:
(i) Primary homothallism:
In Coprinus sterquilinus, a single basidiospore germinates to form a mycelium
which soon becomes organized into binucleate segments bearing clamp
connections at the septa. There is no genetical distinction between the two
nuclei in each cell, and mycelium is capable of forming fruit bodies.
(ii) Secondary homothallism:
In A. bisporus, the basidia bear two spores, but the spores are heterokaryotic.
After meiosis two nuclei enter each spore and a mitotic division may follow.
On germination, a single spore germinates to form a dikaryotic mycelium
capable of producing fruit bodies
Amongst the remaining 90 per cent, of Basidiomycetes reported to be
heterothallic, can be distinguished as follows:

10. What are Heterothallic Fungi?
Heterothallic fungi are the fungal strains which bear one type of
mating type. They are unisexual in nature. Sexual reproduction of
heterothallic fungi occurs between two different compatible
mycelia. Both mating partners contribute nuclei for the formation
of zygote. Identification of the mating partners is a complex
process and it happens via mating type-specific peptide
pheromones and receptors. The recognition between compatible
mating types is essential for a successful sexual reproduction of
heterothallic fungi. These two mating types are similar in
morphology and differ genetically and physiologically.

11. Homothallic vs Heterothallic Fungi
Homothallic fungi are the fungal strains
which are able to produce both male and
female mating types for sexual
reproduction from the same thallus.
Heterothallic fungi are the fungal strains
which have only one type of mating type
and depend on a compatible mating
partner for sexual reproduction.
Sexuality
Mycelium of the homothallic fungi is
bisexual.
Mycelium of the heterothallic fungi is
unisexual.
Type of Sexual Reproduction
Homothallic fungi perform self-
fertilization.
Heterothallic fungi perform outcrossing.
Genetic Variation
Homothallic fungal sexual reproduction
reduces genetic variation.
Heterothallic fungal sexual reproduction
increases genetic variation.
What is the difference between Homothallic and Heterothallic
Fungi?

12. Requirement for a Mating Partner
Homothallic fungi do not depend on a mating
partner from another thallus.
Heterothallic fungi need a different but
compatible mating partner.
Mating Partner
Homothallic mating types are genetically more
or less similar.
Heterothallic mating types are genetically
different.
Examples
Examples of homothallic fungi examples
include Aspergillus nidulans,
Neurospora galapagoensis, etc.
Examples of heterothallic fungi
include Neurospora Crassa, Saccharomyces
cerevisiae, Aspergillus fumigatus, Aspergillus
flavus, etc.

13. Bipolar:
About 25 per cent, of Basidiomycetes examined have been shown to
be bipolar. Besides the Uredinales and most Ustilaginales, Coprinus
comatus, Fomes roseus, and Polyporus betulinus have bipolar
mating systems.
(ii) Tetrapolar:
Coprinus lagopus, Polyporus abietinus, Schizophyllum commune,
Crucibulum vulgare, and Cyathus striatus have tetrapolar mating
systems.
Life Cycle Pattern of Basidiomycetes:
The general life-cycle pattern of the Basidiomycetes has
resemblance with that of the Ascomycetes. The basidiospore on
germination by germ tube gives rise to the haplophasic somatic body
represented by primary mycelium. The primary mycelium often
produces oidia.

14. The oidia may behave as spores and give rise to primary
mycelia, or by spermatization with compatible primary
mycelia take part in the formation of dikaryotic secondary
mycelia. The secondary mycelium may also be formed by
somatogamy between two compatible primary mycelia.
The dikaryotic apical cell of the hypha of the secondary
mycelium develops into basidium.
It may so happen that resting spores may be formed from
the dikaryotic hyphal cells. Each resting spore on
germination gives rise to a basidium. Karyogamy takes
place in the basidium producing diplophasic condition
which is followed immediately by meiosis and ultimately
haploid basidiospores are produced. The basidiospores
germinate to produce haplophasic somatic body.

15. Basidiomycetes
5. Three types of hyphae
a. Primary hyphae – develops from a germinating
basidiospore. Nuclear status = n
b. Secondary hypha – results from fusion of two primary
hyphae. Yields a n+n cell that continues to grow as a
n+n hyphae
c. Tertiary hypha – exactly the same as secondary hypha.
n+n However it has thick walls that enable production
of fleshy and wood sporophores
Primary hyphae Primary hyphae
Secondary hyphae
Tertiary hyphae

16. • Within the basidioma, cells in fertile regions – the
hymenium - will develop into basidia and produce
basidiospores
• As the basidium develops, karyogamy and meiosis take
place
karyogamy
meiosis

17. The mushroom life cycle is similar to that of the filamentous Ascomycota in that
following monokaryons formation, there is a prolonged dikaryon stage prior to to
karyogamy. However, a significant difference is that sexual organs are absent. It is
thought that sexual organs of Basidiomycetes were lost during their evolution and that
vegetative hyphae have taken over the function of sexual organs. Dikaryon formation
begins with the fusion of hyphal cells between compatible monokayons (Fig. 3). The
monokaryon stage of the Basidiomycotina is short-lived and fusion with a compatible
monokaryon occurs soon after basidiospore germination. The dikaryon is the mycelium
that produces the basidiocarp, The dikaryon is the mycelium that produces the
basidiocarp, and as in the Ascomycota, only certain dikaryotic cells will function in
basidia and basidiospore formation, e.g. dikaryotic cells in the hymenium
Figure 3: Dikaryon formation resulting
from fusion of a pair of compatible
monokaryons. Clamp connects may or
Figure 4: Formation
of basidiocarp.

18. The formation of a clamp connection and maintenance of the
dikaryon in a basidiomycete
• Figure 1. a. Terminal cell of hypha.
Growth only takes place at hyphal
tips; b. Hyphal tip elongating. c.
Synchronous division of nuclei and the
beginning of hyphal branch that will
become the clamp connection. One
nucleus (b) migrates into the new
clamp. d. Septum forms at base of the
clamp trapping nucleus b. Nuclei a'
and b' migrate to the hyphal tip, while
nucleus a migrates away from the tip.
e. Septum forms below clamp forming
new cell at hyphal tip. Fusion of the
clamp to the adjacent cell releases
nucleus b to the adjacent cell. Now
both the terminal and subterminal are
binucleate, each with a compatible
pair of nuclei.

19. Reproduksi seksual

21. TWO BASIDUM TYPES
HOLOBASIDIA PHRAGOMOBASIDIA
holobasidium. : a nonseptate unicellular
basidium characteristic of the basidiomycetes. —
called also autobasidium, homobasidium.
Phragmobasidium A type of
basidium that is elongated and
separated into two or four cells by
the production of septa.

22. OTHER EXAMPLES OF PHRAGMOBASIDIA
22

23. Phylum Basidiomycota: Three major classes
Kirk et al 2001
• Class Uredinoiomycetes
– Order Uredinales - basidiocarp (fruiting body) absent .
– The Rusts
• Class Ustomycetes - The Smuts
– Order Ustilaginales basidiocarp (fruiting body) absent .
• . Class Basidiomycetes basidiocarp (fruiting body) present
– Order Tremellales- jelly fungi; Tremella mesenterica -
witch's butter
– Order Auriculariales - fungus ears; Auricularia auricula -
wood ear
– Order Aphyllophorales - chanterelles, tooth fungi,
polypores, coral fungi.
– Order Agaricales - the boletes, gilled mushrooms - inky
caps, oyster mushrooms, etc.
•

24. • Hymenomycetes
• The largest class in the Basidiomycota.
• The basidia are arranged in a layer known as a HYMENIUM
that is fully exposed at maturity.
• The hymenium is the tissue layer on the hymenophore of a
fungal fruiting body where the cells develop into basidia or
asci, which produce spores.
• Basidiocarp is present (mushroom)

25. All members of the Basidiomycota that produce basidiocarps are now
included in a single class, the Basidiomycetes, and the morphology of the
basidiocarp and basidium are characteristics that are now used to
classifying fungi into the various orders of this class.
Order: Agaricales
This is the order that is commonly referred to as mushrooms.
Basidiocarps of this order typically are "fleshy" and have
a stipe (=stalk), pileus (=cap), and lamellae(=gills) where the basidia
and basidiospores are borne .The Basidiospores in this order of fungi are
forcibly ejected from the basidium, into the area between the lamellar
edges, which then allows the spores to fall free from the mushroom and
be dispersed by wind.

26. Order Agaricales

27. • Agaricus spp.(mushroom)
• is a genus of mushrooms containing both
edible and poisonous species, with possibly
over 300 members worldwide . basidiocarp
like umbrella shaped consist from the
following parts:-
• 1-Pileus (cap) 4- stipe(stalk)
• 2-Gills( lamellae) 3-Annulus (ring)

28. 1. Pileus (cap)
2. (gills)
3. Annulus
4. Stipe (stem)
5. Volva
6. Basidium (

29. Order: Aphyllophorales
Species in this order are often coriaceous, leathery to woody, but may
also be fleshy. The basidiocarps and hymenia are more variable than in
the Agaricales. As in the case of the Agaricales, the basidiospores are
forcibly ejected from the basidium and are then dispersed by wind.
Ramaria fragilima, a coral fungus. The basidia and
basidiospores are formed at the tips of the
basidiocarp
Ganoderma applanatum, another polypore

30. Order Aphyllophorales

31. • 3. Gasteromycetes
• Includes fungi known as PUFF-BALLS, EARTH-
STARS and BIRDS' NEST FUNGI.
• The spore-producing hymenium is NOT
EXPOSED at maturity.
• But these fungi have evolved a variety of
mechanisms to ensure efficient spore
liberation.

32. Gasteromycetes (Puff balls)
The Gasteromycetes represent a number of orders that are
not closely related. The common name "puffballs", refers to
the basidiospores being "puffed" from the basidiocarp, in
some species. Unlike the Agaricales and Aphyllophorales,
the puff balls do not forcibly eject their basidiospores. This
has led the puffballs to evolve several interesting means of
basidiospore dispersal .
The terminology having to do with basidiocarp
structure also differ. A hymenium is not formed in this group
of fungi. Basidia and basidiospores are formed throughout
the fertile area of the basidiocarp called the gleba. The part
of the basidiocarp that encloses the gleba is referred to as
the peridium.
.

33. Lycoperdon perlatum is a species belonging to the
order Lycoperdales.
Aseroe rubra is a member of the order Phallales. This
order is commonly called the stink horns because of the
offensive odor that they emit when the basidiospores are
mature. The offensive odor of the gleba, as well as its
coloration, attracts flies, which then disperses the spores
Cyathus sp. is a member of the order Nidulariales. This
order is commonly called the bird's nest fungi because of
their resemblance to a bird's nest with eggs, within.

34. Order Phallales – the stinkhorns

35. Order Lycoperdales – puffballs and
earthstars

36. Order Nidulariales - bird's nest fungi and
sphere throwers

37. Jelly Fungi
"Jelly Fungi" name because of the jelly-like consistency of
the basidiocarp. This type of basidiocarp becomes shrunken
and shriveled, when dried, but with available moisture
revives to its former consistency. This type of basidiocarp
is said to be gelatinous.The life cycle of this order is the
same as that in mushrooms. There are several orders in this
group of fungi and they are delimited by the morphology of
their basidium. The basidia are typically septate, the
exception being the tunning fork basidium, which is
aseptate, but is deeply lobed and produce only two
basidiospores. Three orders will be described below: The
Tremellales, Auriculariales and Dacrymycetales.

38. Order: Tremellales
This order produces cruciate septate basidia This basidium type is so-
called because when viewed, from above, under a compound
microscope, the basidium can be seen to be divided, evenly, into four
chambers by septa that intersect at right angles.
Order: Auriculariales
This order is characterized by having a transversely septate basidium As
is the case of the Tremellales, many species have a gelatinous
basidiocarp, reminiscent of the consistency of jelly. Eg. Auricularia
cornea
Order: Dacrymycetales
This order is characterized by presence of a tunning ford basidium The
basidiocarps are typically some shade of yellow-orange and is
gelatinous, as in the other two orders.eg Dacrymyces palmatus

39. Order Tremellales - jelly fungi

40. Order Auriculariales - fungus ears

41. Mycophagy - To eat or not to eat?
• MYCOPHAGY - (Gr. mykes = mushroom + phagein =
to eat) is a practice that dates back to antiquity.
• Edible mushrooms are good sources of protein (by
dry weight), indigestible "fiber" (due to presence of
chitin), some potential medicinal compounds, and
add diversity to our omnivorous diet (e.g., true
morels, oyster mushrooms, button mushrooms,
shiitake).
• Mushrooms include the sporocarps of certain
members of the Phylum Ascomycota and
Basidiomycota.

42. RUST AND SMUT FUNGI
• Teliomycetes (old name)
or
• Class Uredinoiomycetes
– Order Uredinales - The
Rusts
• Class Ustomycetes - The
Smuts
– Order Ustilaginales
– Uredinales (rusts)
– Ustilaginales (smuts)

43. The Rusts
These are obligate parasites. Generally these require two host to
complete their lifecycle.
Primary hosts – the host on which basidia and basidiospores are
produced.
Alternate host – the other host in the life cycle on which spermagonia
and aecia are produced
Alternative host – the host that a pathogen can infect in place of the
primary or alternate hosts.
Heteroecious – organisms with a primary and alternate host.
Autoecious – organisms that have only a single (primary) host.
Macrocyclic rust – long cycle rust. Produce all 5 spore types.
Demicyclic rust – medium cycle rust. Omits uredia.
Microcyclic rust – short cycle rusts. Produces basidiospores, teliospores
and spermatia.

44. Black Rust of wheat
• In Puccinia graminis (Wheat Rust), there are five
spore stages that are produced and two hosts are
required in the completion ofthe life cyle. The
five stages produced are:
• Stage 0:Spermagonium
• Stage I: Aecium
• Stage II: Uredium
• Stage III: Telium
• Stage IV: Basidium

45. Order Uredinales Order Ustilaginales

46. Puccinia
OCCURENCE:
Puccinia includes about 700 species which are important as they
cause rust dieseases of economically important crop plants such as
wheat,barley, Oats etc.
The most important of all is P. graminis. It is an obligate parsite and is
found in associated with wheat growing areas. It is
an heteroecious (requiring two hosts; wheat and barbery for the
completion of life cycle
Wheat plant is called as Primary host and barberry is the secondary
host or alternate host
it is a macrocyclic and polymorphic rust, in which the life cycle involves
all five spores with a different function.
PLANT BODY:
The mycelium of Puccinia is well developed and consists
of hyphae, which are spetateand intercellular. It obtains nourishment
by small round or branched haustoria.

47. There is a single central dolipore in each septum for the
protoplasmic connection.
During the life cycle, two types of mycelia are produced,
the monokaryotic, mycelium and dikaryotic mycelium.
The dikaryotic mycelium occurs in primary host (Wheat) and the
monokaryotic type is found in alternate host ( barberry)
LIFE CYCLE:
UREDOSPORES Germination of spores
The infection begins in the leaf as the fungus enters through stomata/
injury. The mycelium develops in the host intercellular spaces taking
nutrition from host cells through haustoria. Soon (1–2 weeks after
infection) they start collecting below the epidermis in clusters
called uredosori. Short, erect hyphae called uredinia are produced
by the fungal mycelia. The uredinia function as conidiophores and
form Urediniospores/uredospores from their tips.
The urediniospores are dikaryotic, oval, stalked; wall is thick
spiny/echinulate and brick-red/rust in color.

48. When a large number of spores form, they exert pressure on the host
epidermis and cause its rupture. This exposes the spores and facilitates
their dispersal by wind. This appears as rust or brown colored pustules
or lesions on the host. The infection first appears on the leaf then goes
to the stem, glumes and awn.
Each urediniospore has two germpores (where the wall is thin). The
urediniospores germinate by forming a germ tube when it comes in
contact with a compatible host. The germ tube
produces appressoria which in turn develop the infection peg. The
infection pegs enter the host through stomata/injury and finally hyphal
strands develop and hyphae spread intercellularly. When fully
established, the uredosori are developed again. Urediniospores are the
only type of spores which can re-infect the host.
Urediniospores spread from one wheat plant to another through wind,
thus spreading the infection from plant to plant, and, field to field. This
phase can rapidly spread the infection over a wide area.

49. Dikaryotic • Serves as the asexual (anamorphic) stage, since it infects same host

50. Germination of spores

51. TELEUTOSPORES:
Towards the end of the cereal host’s growing season, the mycelia
produce structures called telia. Telia are produced in the same sorus as
the uredinia. Telia produce a type of spore called teliospore. These are
bicelled, black, thick, smooth walled spores.
They are the only form in which Puccinia graminis is able
to overwinter independently of a host. They remain with the straw after
harvesting where karyogamy occurs and the teliospores
become diploid (2n). The teliospores germinate after a long resting
period and exposure to freezing temperature.

54. BASIDIOSPORES:
Germination of teliospores and formation of basidiospores
A thin hypha comes out of the pore and is called the promycelium. The
teliospore is the site of karyogamy and meiosis. Before germination the two
nuclei fuse and the resultant diploid (2n) nucleus of the spore undergoes
meiosis producing four haploid nuclei. These nuclei migrate into the
promycelium, which then becomes septate. This four celled structure is
the basidium. It is a septate, uninucleate phragmobasidium .Each cell
produces a single haploid basidiospore on sterigmata. Basidiospores are
thin-walled and colorless. They cannot infect the cereal host, but can infect the
alternative host (Usually barberry). They are usually carried to the alternative
host by wind.

55. PYCNIOSPORES:
Once basidiospores arrive on a leaf of the alternative host, they germinate to produce
a haploid mycelium which directly penetrates the epidermis and colonizes the
leaf. Once inside the leaf the mycelium produces specialized structures
called pycnia/spermogonia. The pycnia are flask shaped structures. The pycnia look
like small orange bumps on the leaf surface. They produce two types of haploid
gametes, the pycniospore/spermogonia and the receptive hyphae. The spermogonia
are produced at the tip of short, erect, unbranched hyphae which line the base of the
spermogonium. They are formed in large numbers and released from the ostiole in a
drop of sticky honeydew which attracts insects. The spermatia function as the male
cells. In the neck of the pycnium, long, thin hyphae develop. They grow out of the
pycnium through the ostiole and may branch a few times. These are called receptive
hyphae. They function as the female gamete.
Insects carry spermatia from one leaf to another; splashing raindrops can also spread
spermatia.
Spermatia can fertilize a receptive hypha of the opposite mating type, leading to the
production of a dikaryotic mycelium. This is the sexual stage of the life cycle .

57. AECIDIOSPORES:
This dikaryotic mycelium then moves through the leaf tissue and
reaches the lower surface, here they forms structures called aecidio
mother cells, which produced a type of dikaryotic spores
called aecidiospores. These spores have a warty appearance,
hexagonal shape, and are formed in chains. The chains
of aecidiospores are surrounded by a bell-like structure called aecidial
cup. The aecidial cup is emergent i.e. half in and half out of the leaf
and is made up of monokaryotic fungal cells. It looks like small orange
colored cup like structure on the undersurface of the leaf.
The aecidiospores are able to germinate on the cereal host but not on
the alternative host. They are carried by wind to the cereal host where
they germinate and the germ tubes penetrate into the plant. The fungus
grows inside the plant as a dikaryotic mycelium. Within 1–2 weeks the
mycelium produces uredinia and the cycle is complete.

59. Wheat stem rust

60. Cedar apple rust is caused by Gymnosporangium
juniperi-virginianum;
lacks the uredia stage = no repeating stage

61. Cedar apple rust
• Gymnosporangium juniperi-
virginianae
• Apple is alternate host –
produces pycnia and aecia
• Junipers are primary host
but there is only a telial
stage no uredinial stage so
that elimination of either
host is effective in
controlling the disease

62. White pine blister rust
• Cronartium ribicola
• White pine is alternate host –
produces pycnial and aecial stages
• Gooseberries and currents are the
primary host – produce uredinial
and telial stages
• Asexual stage is not on
economically important host so
eliminating it is effective

66. Ustilaginomycotina - Smuts
• The name Ustilago has been derived from a
Latin word ustus meaning ‘burnt’ because the
members of the genus produce black, sooty
powdery mass of spores on the host plant
parts imparting them a ‘burnt’ appearance.
This black dusty mass of spores resembles
soot or smut, therefore, commonly it is also
known as smut fungus.

67. Ustilaginomycotina
• Classification by Kirk et al 2008
• There are 3 classes
• 1 Entorrhizomycetes
• 2 Ustilaginomycetes
• 3 Exobasidiomycetes

68. Ustilaginomycetes
• It has 2 orders based upon teliospore
germination
• Ustilaginales and Urocystidales
• Ustilaginales: 8 families Ustilaginiaceae,17 generas
• Urocystidales: 4 families Urocystidiaceae, 7 generas
• The generas are identified on the basis of teliospore characteristics
,development and host range

69. Ustilaginomycetes
• Teliospore germination There is two types of teliospore germination
• 1 . Ustilago type :Teliospore forms septate epibasidium (promycelium)
also called phragmobasidium bearing four basidiospores terminally or
laterally
• 2.Tilletia type: epibasidium is holobasidium bearing variable number of
basidiospores only terminally

70. Order Ustilaginales
• Genus Tolyposporium.
• Tolyposporium penicillariae causes smut of pearl millet
• Characteristic feature of Tolyposporium is presence of
outgrowths on the spores which interlocks the spores into
spore ball. The balls break with difficulty and spores
germinate in situ
• Ustilago:
• The symptoms appear only on the floral parts. The floral
spikes turn black and remain filled with the smut spores.
• Ustilago produces two main types of symptoms:
• 1. The blackish powder of spores is easily blown away by the
wind, leaving a bare stalk of inflorescence .Species showing
such symptoms are called loose smuts e.g.,
•

71. • (a) Loose smut of oat caused by U. avenae
• (b) Loose smut of barley caused by U. nuda
• (c) Loose smut of wheat caused by U. nuda var. tritici.
• (d) Loose smut of doob grass caused by U. cynodontis
• (e) Smut of maize caused by U. maydis (U.zeae)
• 2. The blackish powder of spores remains covered by the wall
of the grain (peridium), and the spores are liberated only by
the breaking of wall during thrashing. Species showing such
symptoms are called covered smuts e.g.,
• Covered smut of Barley caused by U. hordei.
• Covered smut of oat caused by U. kolleri.

72. 3. Vegetative Structure of Ustilago:
The mycellium is branched, septate, hyaline, intercellular, with or
without haustoria.
It is of two types:
(i) Primary Mycelium:
It is monokaryotic (uninucleate) and formed by the germination of
basidiospores. It is of very short duration.
(ii) Secondary Mycelium:
It is formed by the dikaryotisation of the primary mycelium. It is
dikaryotic ( bi-nucleate) and extends particularly through the entire life.
In most smuts the mycelium is scattered throughout the various parts of
the host. It is said to be systemic. However, in some smuts (corn smut) it
remains confined to certain parts of the host and is called localised.

73. . Reproduction in Ustilago:
It is of two types:
(1) Asexual Reproduction
(2) Sexual Reproduction
(1) Asexual Reproduction:
It takes place by fragmentation, budding of basidiospores and
formation of conidia. However, it is of rare occurrence.
(2) Sexual Reproduction:
Ustilago is autoecious i.e., it completes its life cycle on a single
host. Sex organs are completely absent. It produces two kinds of
spores during its life cycle i.e., Teliospores or teleutospores and
basidiospores

74. Spore Formation:
The mycelium grows keeping pace with the growth of the host plant.
It is chiefly confined to the stem .At the time of flowering the
mycelial hyphae enter into the ovaries of flowers
.
Within the ovary each hypha grows vigorously and branches
repeatedly to form a dense mass of hyphae .The latter destroy the host
tissue in the ovaries and surrounding floral parts. The cells of these
hyphae are binucleate.
The hyphae undergo additional septation to form short binucleate
cells. These cells swell and round off to form binucleate smut spores
.The smut spores are called the brand spores(teliospores.)
Its thick wall can be differentiated into two layers:
(1) The outer thick layer i.e., exine or exosporium and
(2) The inner thin layer i.e., inteine or endosporium
The smut spores are disseminated by wind, insects or water,

76. Disease Cycle
The loose smut of wheat is a systemic disease. It is seed borne. As
the infected grain is sown and germinates the dormant fungus
mycelium within the grain resumes activity. It grows best in or near
meristematic tissues keeping pace with the growth of the host plant
.At the flowering time, the hyphae reach the inflorescence region
and accumulate in the floral parts chiefly the florets which are
subsequently completely destroyed. The hyphae become swollen
and additionally septate
The segments, which are binucleate, round off, separate and secrete
thick walls to become smut spores which are frequently called
teliospores. The teliospores serve as a means of propagating the
disease during the growing season.
They are readily carried from the smutted ears by air current at a
time when the healthy plants are in the flowering stage.
The teliospores fall on the feathery stigmas of healthy wheat
flowers. Under suitable conditions (warmth and moisture) the
spores germinate on the stigma

77. Germination of Teliospore:
Under favourable conditions (moisture and temperature) and
falling on suitable substratum smut spores germinate within
a day. Prior to germinatium the two nuclei (one two of ‘+’
strain and other of strain) in each teleutospore fuse to form a
synkaryon
The diploid nucleus migrates into the promycelium and
divides meiotically resulting in a row of four nuclei Three
transverse septa are laid down in the promycelium resulting
in the formation of four uninucleate cells. Each uninucleate
cell of the promycelium sprouts a bud towards its upper end.
Each nucleus divides mitotically into two, one of which
remains in the cell but the other migrates into the developing
bud. These uninucleate buds are called basidiospores. Out of
four basidiospores two are of + strain and two are of – strain.

78. Without dispersing to any alternate host plant, the
basidiospores germinate right where they are.
The hyphae of two compatible basidiospores then fuse to establish
a dikarytic stage.
After germination inside the ovary, the fungal mycelia invade the
developing embryo in the seed.
The fungus stays alive in the seed until the next growing season, when it
is planted along with the seed.
As the developing plant grows, the fungus grows with it. Once it's time
for the flowers to form, teliospores are produced in place of the flowers
and develop where the grain would be.
Plants which are infected with Ustilago spp. actually grow taller and
flower earlier than their healthy counterparts. This gives the infected
plants an advantage in that the flowers of uninfected plants are more
physically and morphologically susceptible to infection. The teliospores
in the smutted grain heads disperse to the open flowers of the healthy
plants, and the cycle continues.

80. Smuts
• A number of
economically important
plant pathogens – corn
smut, Ustilago maydis,
loose smut of oats,
Ustilago avenae, bunt
and stinking smut of
wheat, Tilletia spp.

81. Ustilago violacea - anther smut. Systemic infection but
forms spores only in anthers (replaces pollen)
causes sex change in plant
Loose smut, a disease of barley
caused by Ustilago
nuda. Spores replace grains

82. Ustilago maydis - corn smut. spores often replace entire cob

83. Class Exobasidiomycetes
Order Tilletiales (Teliosporic)
Genus Tilletia :Diseases caused by Tilletia are caused bunts
Bunt of wheat/stinking Bunt is caused by two species T caries (smooth spores) and
T laevis/T foetida (rough spores)
Infected plants emits fishy smell due to volatile compound (trimethyl amine)produced
by fungus
 Karnal Bunt or Partial Bunt is caused by Nevossia indica (T.indica) discovered by
Mitra in 1931
Dwarf Bunt caused by T controversa
Order Exobasidiales ( Non Teliosporic)
This order contains plant parasites that forms galls on leaves
This order is characterized b by foration of basidia in a layer uncovered on the leaf
surface hence the name
The basidiospores are ballistospores i.e. Discharged forcibly
Exobasidium vexans causes blister blight of tea

84. Comparison of Rust & Smut Fungi
Uredinales (rusts) Ustilaginales (smuts)
1. Teliospores terminal. 1. Teliospores intercalary.
2. Basidiospores 4, discharged from sterigmata. 2. Basidiospores variable in number, not on
sterigmata, not discharged.
3. Spermagonia produce dikaryotic stage. 3. No spermagonia; dikaryotic stage. stage
arises from fusion of any two compatible cells.
4. Clamp connections absent. 4. Clamp connections common.
5. Many species require two hosts for complete
life cycle.
5. Never requires two hosts.
6. Most species unculturable on artificial media. 6. Most species readily culturable.
7. Infections usually localized. 7. Infections usually systemic.
8. Teliospores in telial sori, usually on stems or
leaves.
8. Teliospores replace host host organs, usually
ovaries and anthers.
9. Attack ferns, gymnosperms, or angiosperms. 9. Attack only angiosperms.