8/14/2019 Morphology, Life Cycle and Economic Importance Of

1/21

MORPHOLOGY, LIFE

CYCLE AND ECONOMICIMPORTANCE OF FUNGI

OYINLOYE, J.M. ADEDEJIACHIEVERS UNIVERSITY, OWO

COLLEGE OF NATURAL AND APPLIED

SCIENCES

8/14/2019 Morphology, Life Cycle and Economic Importance Of

2/21

Brief Historical Account

Gleditsch, a German botanist attempted ashort classification of fungi in 1753

Fontana, an Italian scientist worked onrust of cereals caused by fungi in 1767

In the 19th century, De Bary (1831-88)

worked on the physiological andbiological nature of fungi and publishedhis new classification scheme in 1884. Healso discovered the lichens.

8/14/2019 Morphology, Life Cycle and Economic Importance Of

3/21

GENERAL DESCRIPTION

Fungi (sing. Fungus) originated from a Greek

wordfungos mushroom. They are a group

of thallophytes lacking in chlorophyll.

Majority of the fungi are usually unicellular

or colonial but a few complex forms such as

mushroom and puffballs have a limitedform of cellular specialisation.

8/14/2019 Morphology, Life Cycle and Economic Importance Of

4/21

PUFFBALL

Fly Agaric Mushroom

The brightly colored fly agaric mushroom is a deadly poisonous mushroom. Containingibotenic acid and a number of other organic poisons, the fly agaric can cause severedamage to the central nervous system, blood vessels, kidneys, liver, and muscles.Symptoms, which may not become apparent for 8 to 12 hours or longer, include nausea,vomiting, and severe diarrhea and can lead to coma and death.

8/14/2019 Morphology, Life Cycle and Economic Importance Of

5/21

The kingdom is filled with over 100,000 spps

which can be generally divided into 2;

1. Macroscopic fungi (mushrooms, puffballsand gill fungi)

8/14/2019 Morphology, Life Cycle and Economic Importance Of

6/21

2. Microscopic fungi (molds and yeast)

8/14/2019 Morphology, Life Cycle and Economic Importance Of

7/21

Cells of the microscopic form exist in two

forms; yeast and hyphae.Yeast: it is differentiated by its round-oval

shape and by its mode of asexual

reproduction; mainly budding. Some produce

pseudohypha (chains of yeast cells when

buds still remain attached to the mother cell).

8/14/2019 Morphology, Life Cycle and Economic Importance Of

8/21

Hyphae: these are long, threadlike cells foundin the body of filamentous fungi/molds.

While some fungi exist as yeast, others arehyphae, but some are dimorphic (either)depending on enviromental factors e.g.

pathogenic molds.

8/14/2019 Morphology, Life Cycle and Economic Importance Of

9/21

Dimorphism in C albicans. DYC, Daughter yeast cell; GT, germ tube; H,

hypha; Ph, pseudohypha; YMC, yeast mother cell. (X8,980)

8/14/2019 Morphology, Life Cycle and Economic Importance Of

10/21

CLASSIFICATION OF FUNGIPHYLUM(COMMON NAME) EXAMPLE(S)

Ascomycota (sac fungi) Neurospora, Morchella,Ergot

Basidiomycota (club fungi) Agaricus, Amanita,Cortinarius

Chytridiomycota (chytrids) Allomyces, Chytridium

Deuteromycota (fungi imperfecti) Arthrobotrys,Aspergillus

Zygomycota (Terrestrial fungi) Rhizopus, Pilobolus.

8/14/2019 Morphology, Life Cycle and Economic Importance Of

11/21

NUTRITION

All fungi are heterotrophic i.e. they acquirenutrients from a wide variety of organicmaterials.

Most are saprobes i.e. they feed on remnants ofdead plants and animals in soils or aquatichabitats.

They can also be parasites on bodies of livinganimals and plants though a few are obligatelydependent on living host.

8/14/2019 Morphology, Life Cycle and Economic Importance Of

12/21

Their feeding method is by extracellular

digestion i.e. they penetrate the substrate

and secrete enzymes to reduce it to small

molecules that can be easily absorbed. They

produce many enzymes that can degrade

substances like hair, nail, feathers, cellulose,petroleum products, wood, rubber etc.

The diseases they cause on living hosts are

tagged MYCOSES. They produce toxins

which are harmful to man, and spores which

can elicit allergies or other respiratory

diseases.

8/14/2019 Morphology, Life Cycle and Economic Importance Of

13/21

8/14/2019 Morphology, Life Cycle and Economic Importance Of

14/21

MICROSCOPIC FUNGI

Colonies of yeast are similar with that of

bacteria (soft, uniform texture & in

appearance)

8/14/2019 Morphology, Life Cycle and Economic Importance Of

15/21

Colonies of filamentous fungi/molds have somecottony, hairy or velvety textures.

The woven intertwining mass of hyphae iscalled MYCELIUM.

8/14/2019 Morphology, Life Cycle and Economic Importance Of

16/21

In most fungi, the hyphae are divided intosegments by cross walls called SEPTA, a

condition known as septate. The septa caneither be complete crossing or partial with asmall pore which allows for inter-compartmental exchange of nutrients and

organelles.Non-septate hyphae contain no cross walls,

thus, are long, continous tube.

Hyphae can be classified into vegetative; thevisible mass growth on substrates, which intime gives rise to the reproductive hyphaethat produces the reproductive bodies

called SPORES.

8/14/2019 Morphology, Life Cycle and Economic Importance Of

17/21

REPRODUCTIONPropagation can be by simple outward

growth already existing hypha or by

fragmentation, in which fragmented

segment grows into a new colony.Propagation is also possible by special

bodies called SCLEROTIA a compact,

hard rounded mass of hyphae.The primary means of reproduction is by

SPORE production.

8/14/2019 Morphology, Life Cycle and Economic Importance Of

18/21

The compactness and light weight of spores

make its dissemination easy by air, water

and living things.The fungal spore is different from bacteria

spore in that it is used for multiplication,

dissemination, production of geneticvariation and survival.

Because of the diversity of spore production,

the spore and its bearing/forming structurecan be used for classification and

identification.

8/14/2019 Morphology, Life Cycle and Economic Importance Of

19/21

Fungi may reproduce sexually or asexually.

Spores may be either sexual or asexual in

origin. Sexual spores include ascospores,basidiospores, oospores and zygospores,

which are used to determine phylogenetic

relationships. Sexual reproduction occurs by

the fusion of two haploid nuclei (karyogamy),

followed by meiotic division of the diploid

nucleus. Asexual spores are produced in sac-

like cells called sporangia and are calledsporangiospores. Asexual reproduction results

from division of nuclei by mitosis.

8/14/2019 Morphology, Life Cycle and Economic Importance Of

20/21

ECONOMIC IMPORTANCE

They cause superficial and systemicinfections in humans.

They produce some chemicals capable of

causing allergies or neurologicaldisturbance or even death.

They are pathogenic to field plants and

harvested produce.

8/14/2019 Morphology, Life Cycle and Economic Importance Of

21/21

They decompose organic matter, returning

essential nutrients into the soil.

They form association with plant rootshelping in the absorption of water and

nutrients the mycorrhizae.

They are a source of antibiotic, alcohol,organic acids and vitamins production in

Industries.

The yeast (Saccharomyces) producesalcohol in beer and wine and also the gas

that makes bread dough rise.