This document provides information on the classification and reproduction of fungi. It discusses: - The key structures of fungi including hyphae, mycelium, and cell walls. - Modes of nutrition and reproduction for fungi, including asexual reproduction through spores or fragmentation, and sexual reproduction through fusion of nuclei or entire protoplasts. - The five major divisions of fungi based on reproduction and genetics: Zygomycota, Ascomycota, Basidiomycota, Deuteromycota, and Chytridiomycota. Characteristics and examples are outlined for each division.

1. Classification and reproduction
of fungi
Dr. Aswartha Harinatha Reddy
Department of Life Sciences
Bangalore

2. Introduction:
 A fungus is a eukaryotic organisms that includes microorganisms
such as yeasts and molds, as well as the more familiar mushrooms.
 Fungus are heterotrophs, they acquire their food by absorbing
dissolved molecules, typically by secreting digestive enzymes into
their environment. Fungi do not photosynthesise.
 The scientific discipline dealing with fungi is called mycology.
 The study of fungal toxins and their effects is called
mycotoxicology, and the diseases caused by fungi in animals are
known as mycoses.

3. Microscopic structures of fungi:
The body or vegetative structure of a fungus is called a
mycelium (a network of hyphae).
Thallus is the undifferentiated vegetative tissue of some
organisms in diverse groups such as algae, fungi.
The fungal cell wall made up of chitin.
Most fungi grow as hyphae, which are cylindrical, thread-
like structures, 2–10 µm in diameter and up to several
centimeters in length.

4. Hyphae grow at their tips (apices); new hyphae are
typically formed by emergence of new tips along existing
hyphae by a process called branching.
These growth processes lead to the development of a
mycelium, an interconnected network of hyphae.

5. Hyphae can be either septate or coenocytic:
 Septate hyphae are divided into compartments separated by
cross walls (internal cell walls, called septa), with each
compartment containing one or more nuclei.
 Septa have pores that allow cytoplasm, organelles, and
sometimes nuclei to pass through the pores.
 Coenocytic hyphae are not are divided into compartments.

7.  Many species have developed specialized hyphal structures
for nutrient uptake from living hosts;
 Examples include haustoria in plant-parasitic species of most
fungal phyla.
 Arbuscules of several mycorrhizal fungi, which penetrate into
the host cells to consume nutrients.
 In Rhizopus fungi, rhizoids are small branching hyphae that
grow downwards from the mycelium that anchor the fungus
to the substrate, where they release digestive enzymes and
absorb digested organic material.

8. Nutrition of Fungi:
 Most fungi are saprophytes, securing their nutrients from dead
organic material.
 Many fungi release hydrolytic exo-enzymes that digest external
substrates.
 Glycogen is the primary storage polysaccharide in fungi. Most
fungi use carbohydrates (preferably glucose or maltose) and
nitrogenous compounds to synthesize their own amino acids and
proteins.
 Fungi usually are aerobic. Some yeasts, however, are facultative
anaerobic and can obtain energy by fermentation, such as in the
production of ethyl alcohol from glucose.

9. Reproduction:
 Reproduction in fungi can be either asexual or sexual.
Asexual:
 Asexual reproduction occurs via vegetative spores (conidia) or
through mycelial fragmentation.
 Mycelial fragmentation occurs when a fungal mycelium separates
into pieces, and each component grows into a separate mycelium.
 The most common method of asexual reproduction is spore
production.
 Asexual spore formation occurs in an individual fungus through
mitosis and subsequent cell division.

10. Asexual Reproduction of Fungi:
There are several types of asexual spores:
 A hypha can fragment (by the separation of hyphae through
splitting of the cell wall or septum) to form cells that behave
as spores. These cells are called arthroconidia or
arthrospores.
 If the cells are surrounded by a thick wall before separation,
they are called chlamydospores.


11.  If the spores develop within a sac i.e sporangium at a hyphal
tip, they are called sporangiospores.
 If the spores are not enclosed in a sac but produced at the tips
or sides of the hypha, they are termed conidiospores.
 Spores produced from a vegetative mother cell by budding are
called blastospores.

12. Rupture of
sporangium

13. Sexual reproduction:
 Sexual reproduction in fungi involves the union of compatible
nuclei.
 Depending on the species, sexual fusion may occur between
haploid gametes, gamete-producing bodies called gametangia.

 Sometimes both the cytoplasm and haploid nuclei fuse
immediately to produce the diploid zygote (2n).
 Meiosis takes place in diploid zygote and number of
chromosomes becomes half result in the formation of sexual
spores.

14.  For example, in the zygomycetes the zygote develops into
a zygospore, in the ascomycetes, an ascospore, and in the
basidomycetes; a basidiospore.
 The male gametes are called the antherozoids and the
female ones are the eggs.
 The male gametes formed inside the gametangia called
antheridium.
 The female gametes formed inside the gametangia called
oogonium.

15. The most common methods of sexual reproduction in fungi:
Planogametic copulation:
 This type of sexual reproduction involves the fusion of two motile
gametes.
 The motile gametes are known as planogametes.
 Based on structure and size planogametes the Planogametic
copulation is divided into 3 types:
1. Isogamy
2. Anisogamy
3. oogamy

16.  Isogamous: The male
and female gamtes are
of same shape and size
both are motile.
 Ex: Synchytrium.
 Anisogamous:
Morphologically
dissimilar. Different in
size and shape. (Male
is active and smaller
than female) ex:
Allomyces
 Oogamy:
 Fusion of non motile
female gamete and
motile male gamete is
known as Oogamy.

17. Gametangial Contact:
 Here gametes are not produce form the gametangia.
 In this method two gametangia of opposite sex comes in
contact and one or more nuclei migrates from male to the
female.
 The male nuclei enters the female gametangium through a
pore developed by the dissolution of gametangial walls at the
point of contact while in other species fertilization tube acts as
a passage or the male nuclei.
Ex: Aspergillus, Penicillium.

18. Gametangial Copulation:
 Entire protoplast is
transferred into the female
gametangia a involes the
complete fusion of two
protoplast.
 e.g., Mucor, Rhizopus

19. Spermatization:
 In this reproduction, sex organs are completely absent.
 It involves the formation of small spores or seed like
structures or spermatia by male hyphae.
 Spermatia acts as male gamete which is uninucleate or spore
like and carried out by wind, insects to the female
(Receptive) hypha which serves as a female organ.
 Ex: Ascomycetes

21. Somatogamy:
 Here sex organs are not formed.
 The fusion occurs between female and male vegetative
hyphae.
 This results in the formation of dikaryotic hyphae.

22. Classification of Fungi:
 Based on variations in sexual reproduction and 18S rRNA
studies, molecular microbiologists mycologists classifies the
fungi into five divisions.
Zygomycota or Zygomycetes
Ascomycota or Sac fungi
Basidiomycota or Club fungi
Deuteromycota or Imperfecti fungi.
Chytridiomycota or Chytridiomycetes

23. Division: Zygomycota or Zygomycetes:
 Also known as Conjugation Fungi, which are mostly saprotrophic,
rarely parasitic.
 The mycelium is coenocytic (multinucleate, aseptate).
 Asexual reproduction by Chlamydospore formation.
 Sexual reproduction occurs through gametangial copulation or
conjugation. Because of it, zygomycetes are also called conjugation
fungi.
 Sexual reproduction produces a resting diploid spore called
zygospore. Because of the presence of zygospore, the group of fungi
is called zygomycetes.

24.  The thick-walled sexually produced zygospore formed by the
complete fusion of the protoplasts of two gametangia.
 The zygospore germinates to produce a hypha, the
promycelium which bears a terminal sporangium.
 Inside the sporangium haploid spores are present, rapture of
sporangium release sexual spores, germinate into new
mycelium.

26.  Rhizopus stolonifer and R. nigricans is popularly known as
black bread mould.
 Both Rhizopus and Mucor species (e.g., Rhizopus oryzae,
Mucor javanicus) are used in alcoholic fermentation.
 The two also produce a number of organic acids like citric acid,
lactic acid and fumaric acid.

27. Division: Ascomycetes – The Sac Fungi:
 Many species are quite familiar and economically important like
Yeast, Aspergillus and Penicillium.
 The mycelium consists of septate hyphae.
 Asexual reproduction by Conidiophores formed at the tip of hyphae.
 Which produce spores in a distinctive type of microscopic
sporangium called an ascus.
 Sexual reproduction takes place through fusion of gametangial
contact between an antheridium and ascogonium (Female sex organ).

28.  Economic Importance:
 Aspergillus species used for production of alcohol, citric acid,
gluconic acid, glycerol, В-complex vitamins, enzymes and
antibiotics.
 P. chrysogenum yields the antibiotic penicillin. The latter was
the first commercial antibiotic. It was formerly obtained from
P. notatum. P. griseofulvum produces antifungal drug
griseofulvin.
 Yeasts used by brewing industry are Saccharomyces cerevisiae
(Beer or Baker’s yeast). Under anaerobic conditions sugary so-
lutions inoculated with yeasts are converted into alcoholic
beverages, e.g., beer, wine,

29. Basidiomycetes – The Club Fungi:
 Basidiomycetes are the most advanced and most commonly
seen fungi. e.g., Mushrooms.
 Basidiomycetes are the best decomposers of wood.
 Basidiomycetes are able to decompose both cellulose and
lignin. Lignin is not metabolised by most other fungi and even
bacteria.
 Sexual reproduction by Spermatization.
 Common examples are Agaricus campestris, A. bisporus.

30.  Basidiomycetes are
named for their
characteristic structure
or cell, the basidium,
that is involved in
sexual reproduction.
 Basidium is produced at
the tip of hyphae and
normally is club shaped.

31. Division Deuteromycota or The Fungi Imperfecti:
 Deuteromycetes is an artificial class of fungi, sexual stage is
either absent or not known.
 The mycelium is usually septate.
 Asexual reproduction often occurs by conidia.
 Colletotrichum falcatum produces red rot of sugarcane.
 Tikka Disease in groundnut Cercospora personata.

32. Division Chytridiomycota:
 Chytridiomycetes, also known as chytrids.
 These are simple terrestrial and aquatic fungi that reproduce
asexually by forming motile zoospores with a single flagella.
 The entire organism is microscopic in size and may consist of
a single cell, a small multinucleate mass.
 Usually chitin is the major constituent of chytrid cell walls.
 Chytrids are thought to have been derived from a protozoan
ancestor having similar flagellation.

33. Thank you..