KINGDOM: FUNGIstaff.oouagoiwoye.edu.ng/uploads/412_COURSES... · Deuteromycota (imperfect fungi) The first four divisions, to be discussed in this lecture, are grouped as heterotrophic

Learning with Prof Bup www.bupoyesiku.net Updated 1st January 2020

PLS201: BIOLOGY OF SEEDLESS PLANTS

(Tuber Mushroom)

KINGDOM: FUNGI

OLABISI ONABANJO UNIVERSITY | Department of Plant Science

http://www.bupoyesiku.net/

OLABISI ONABANJO UNIVERSITY PLS201: CRYPTOGAMS

Updated 1st Janary 2020

Learning with Prof Bup www.bupoyesiku.net Page 1

Contents

Contents ........................................................................................................................................................... 1

Introduction ................................................................................................................................................. 2

Objectives ................................................................................................................................................... 2

Main content ............................................................................................................................................... 2

Background of fungi .............................................................................................................................. 2

Members of fungi ................................................................................................................................... 3

Characteristics of fungi ......................................................................................................................... 3

Forms/Habits of fungi .......................................................................................................................... 10

Habitats of fungi ................................................................................................................................... 10

Ecology of fungi ................................................................................................................................... 11

Economic uses of fungi ...................................................................................................................... 11

Conclusion ................................................................................................................................................ 12

Summary .................................................................................................................................................. 12

References/Further readings ................................................................................................................. 12

Tutorial-marked questions ..................................................................................................................... 13




Introduction

In our previous lectures, (cryptogams and algae), we discussed the general cryptogams

and the most straightforward group of spore plants, the algae. It is interesting to know that

animals, plants and fungi are specialised multicellular groups derived from kingdom

Protista (algae). In today’s lecture, we shall treat the kingdom of fungi. Fungi is a group of

organisms that share specific characteristics with both plant and animal. Although their

inability to photosynthesise by the lack of chloroplast and cellulose cell walls, their cell

walls are made up of chitin, a component in insect exoskeleton. However, fungi are

capable of producing spores, like the photosynthetic cryptogam plants. Before going into

treating the fungi, we need to know the three basic modes of nutrition in eukaryotic

unicellular and multicellular organisms. These mode of nutrition are ingestion,

photosynthesis and absorption. Now we shall go on to treat the various groups of fungi

and their significant characteristics, ecological and economic uses.

Objectives

At the end of this lecture, we will be able to:

1. raise awareness and extend the knowledge of the fungi

2. have the needed skills to identify members of the fungi around

3. know the importance and the role of fungi in any ecosystem

Main content

Background of fungi

Mycology is the study of the fungi kingdom. The fungi subdivided into two, micro and

macrofungi. The fungi indeed contain some of the most strange and fascinating species.

There are about 100,000 known species. Majority of the fungi around are heterotrophic

(unable to carry out the process of photosynthesis), and they rely on organic nutrients

(cellulose and proteins) from their host or substrate. It is the conventional concept that

fungi secrete a powerful digestive enzyme, outside their body, which breaks down living

or dead organisms into sugars and amino acids. Subsequently, they absorb the nutrient

through their body walls. It will be interesting to know that the individuals of filament

(hyphae) knotted together to form a mycelium. Interestingly, the mycelia (knotted hyphae)

of some fungi can cover an area more than 12 hectares (30 x 2.471) acres of forest floor

underneath the soil surface. No doubt fungi could be one of the world's most abundant

living organisms.




Members of fungi

Early classification of fungi include five divisions

1. Acrasiomycota (cellular slime moulds)

2. Myxomycota (slime moulds)

3. Oomycota (water moulds)

4. Chytridiomycota (Chytrids)

5. Eumycota-(true fungi)

6. Deuteromycota (imperfect fungi)

The first four divisions, to be discussed in this lecture, are grouped as heterotrophic

protists (slime mould, water mould and cellular slime mould), while the phototrophic

protists are algae (see our previous lecture on the kingdom Protista). This group of

heterotrophic protists generally produces motile cells (including swarm cells and

zoospores) during certain stages of their life cycles. The fifth division of fungi this lecture

is the true fungi, including the family Zygomycetes, Ascomycetes, and Basidiomycetes.

The last division is an exceptional division, with unknown sexual stages. This observation

is remarkably strange because certain species in this division have in the past classified

more than twice by independent taxonomists as member of the family ascomycetes and a

family of Deuteromycetes.

Characteristics of fungi

We are going to discuss here both the general characteristics of fungi and the specific

characters of each division. As we have already known from the start of this lecture, fungi

are acellular or multicellular with well-defined nuclei and rarely are they unicellular

organisms; they have many nuclei occupying the non-partitioned (non-septate) mycelium.

In certain groups, this mycelium becomes partitioned (septate) in reproductive stages of

the life cycle.

As we know from the beginning of this lecture that fungi are unique organisms in

the sense that they are difficult to classify as either plant or animal, instead considered

under a separate kingdom. The comparative characteristics of plant and animal with the

fungi are enumerated here (Table 1).




Table 1. Comparative characteristics of plant and animals shared with fungi

Attribute Plant Animal

Pigmentation Chlorophylls Melanins/flavins

Cell walls Cellulose Chitin

Nutrition Photo-autotrophic Heterotrophic

Growth form Leafy/thallus Hyphae/Yeast

Stored food Starch Glycogen

At this point, we shall discuss each of the divisions under the fungi in great details.

Acrasiomycota (cellular slime moulds)

The Acrasiomycota division includes the heterotrophic species that exist as separate

amoeba-like structure. Cellula slime mould swarms together to form pseudo-plasmodium

that later differentiates into a fruiting body. Other characteristics of this division include

1. They form sexual reproductive structure (macrocytes)

2. Zygotes (fused pair of mould) attract and ingest single amoeba-like slime moulds

3. Their principal mode of nutrition is by ingestion

4. About 70 species are known

Myxomycota (slime moulds).

The Myxomycota division includes terrestrial plasmodial slime moulds (Fig1). The

common characteristics of plasmodial slime mould include

1. Heterotrophic, multinucleate, creeping, amoeboid plasmodium

2. Adult plasmodial produce multinucleate sporangia that give rise to many spores

3. Sexual reproduction is rare and occasionally observed

4. A dominant mode of nutrition is by ingestion

5. There are approximately 450 species

Oomycota (water moulds).

The Oomycota division includes aquatic and terrestrial species with motile cells at certain

stages of their life cycle. Common characteristics of this division include

1. A pair of flagella (tinsel and whiplash)

2. Cell walls composed of cellulose

3. They store their food as glycogen (animal glucose)

4. Close to 500 species identified




Figure1. Mobile plasmodial slime mould made of a mass of hyphae forming the body

(mycelium).

Chytridiomycota (Chytrids)

The division Chytridiomycota includes aquatic heterotrophic species with motile cells at

certain stages of their life cycle. Other characteristics include

1. Cell walls made up of chitin

2. Motile cells equipped with single posterior whiplash flagellum

3. They stored their food as glycogen

4. There about 800 species

At this point, we must know that the correct moulds (Eumycota), which is for discussion

next, is subdivided into five classes for your better understanding of this lecture. The

classes include Zygomycetes, Ascomycetes, Basidiomycetes, Hymenomycetes and

Gasteromycetes




Zygomycetes

The Zygomycetes class includes terrestrial fungi with visible septate hyphae only

during the formation of reproductive bodies. Other characteristics include


2. Few forms endomycorrhizal with individual vascular plants

3. There are about 600 species

Ascomycetes

The Ascomycetes class includes terrestrial and aquatic fungi with perforated hyphae

septate. It is interesting to know here that the hyphae portion without perforated

septate mark off for the production of the reproductive propagules (spores or gametes).

Many species in this class have their, hyphae combined to form a cup-like structure

called ascocarps. Other characteristics include


2. Sexual ascus cells undergo meiosis to form ascospores

3. Asexual reproduction is by budding as found in Yeasts (unicellular)

4. There about 30,000 species out of which sexual stages do not occur or known in

25,000 species (imperfect fungi)

Note that Deuteromycota (imperfect fungi) will be discussed in details in another

lecture because this division lacks an actual sexual cycle.

Basidiomycetes

The Basidiomycetes class includes only terrestrial fungi. Like in many ascocarps, the

hyphae septate are perforated and the non-perforated septate cut off the reproductive

structure (spores). The sexual reproductive structure is the basidia, which undergoes

meiosis to produce basidiospores. Other characteristics include

1. A pair of nuclei (dikaryotic) within each septate compartment (a unique character

not found in other fungi)

2. They form ectomycorrhizae with higher plants

3. There are about 25,000 species

It is essential also to note here that the division Basidiomycota in addition to

Basidiomycete, include other classes such as Hymenomycetes, Gasteromycetes, and

Teliomycetes, which we shall discuss next.




Hymenomycetes

1. Formation of basidia in a hymenium (fertile layer consisting of asci or basidia)

2. Basidia (club-shaped sexual reproductive cells) are either septate or aseptate

3. Explosive discharge of the basidiospores (ballistospores)

4. Examples include mushroom, coral fungi, shelf or bracket fungi and tuber fungus

Figure 2. Basidiomycetes. A= Bracket fungus. B=Coral mushroom. C=Bird’s nest

B

A

C




Gasteromycetes

1. No distinct hymenium (fertile layer)

2. Saprobes growing in soil, dung or dead wood

3. Occasionally form a mycorrhizal association with vascular plants

4. Produce basidiospores

5. Basidiospores discharged passively

6. Examples, puffballs, earthstars, stinkhorns and bird’s nest fungi

Figure 3. Gasteromycetes. A=Puffballs. B=Stinkhorn.

Teliomycetes

1. They do not form basidiocarp

2. They form powdery septate spores

3. They are plant pathogens

4. They produce terminal teliospore (thick-walled resting spores)

5. Teliospores (basidia or sporidia) forcibly discharged

6. Examples, rust and smuts

A B




Figure 4. Corn smut fungus on an ear of corn

At this point, we need to know the poisonous mushrooms. Few rules of thumb will

guide us as we discuss it next

Characteristics of poisonous mushrooms (Fig 5).

1. white basidiospores 2. a cuplike volva at the base of the stalk 3. a ring or annulus on the stalk further or close to the basidiocarp 4. remnants of the universal veil on the umbrella-like cap (basidiocarp)

Note here that mostly all these traits discussed here are short-lived, depending on the

age and condition of a fungus. These characters are not always reliable to depend upon

to determine the poisonous fungi. Other methods include silver coin and a taxonomic key.

If a coin dropped in boiled mushroom water, it turned black. The mushroom is poisonous!

Again this test is not a reliable one. A good and reliable method is the use of a taxonomic

key, which can only be done by a specialist who understands the terminology of the fungi.




Figure 5. Typical poisonous mushroom. A=Basidiocarp. B=Annulus. C=Volva. D=Stalk

At this point, it will interest us in knowing that lichen, which we shall treat in our next

lecture, is not a single organism, but a symbiotic association between a fungus

(ascomycetes) and certain green algae or photosynthetic bacteria (Cyanobacteria).

Besides, there are also members of basidiomycetes that form associations with green

algae, but they are not lichen.

Forms/Habits of fungi

Fungi life form is either saprophytic or parasitic.

1. Hyphae

2. Mycelium

3. The fruiting body (mushroom)

Habitats of fungi

Fungi mode of nutrition could either be saprophytic or parasitic. The latter fungi feed on

living organisms while the former concentrate on dead organisms is causing accelerated

A

B C

D




decomposition. The saprophytic fungi are found generally on woods in varying stages of

decomposition.

Ecology of fungi

It is essential to know that both fungi and bacteria are essential decomposers of our

natural ecosystems. They are vitally important as decomposers. The fungi are majorly

terrestrial organisms, which share characteristics with both plant and animal. They are

heterotrophic, obtaining their food by external digestion using a powerful enzyme and

subsequently absorbing the nutrients. Fungi vital function is to close the gaps of many

nutrients cycle and recycle vital elements (nitrogen and phosphorus) back into the

ecosystems.

Economic uses of fungi

Fungi are beneficial to global ecosystems. Many forms are pathogenic (disease-causing).

They have their positive and negative benefits. It will surprise us that the positive benefits

could exceed the negative ones.

Positive benefits of fungi

1. The yeast strains cause the fermentation of grains and grapes in the making of beer and wine and in rising of bread dough

2. Penicillium spp. is a valuable source of the antibiotic penicillin growing on stale bread and fruit

3. Few basidiomycetes, mushrooms (umbrella-shaped), truffles (underground tuber), chanterelles (yellowish) and boletus (pore-like surface) are edible

4. Androstenol extracted from truffles, similar to a pheromone secreted by an animal, is added to certain cosmetics to attract the opposite sex

5. Ergot fungus (Claviceps purpurea) is a good source of ergotamine, which a. Enhances muscle and blood vessel constriction b. Relieves the horrible pain of migraines, c. Stimulates uterine contraction during childbirth and d. Prevents haemorrhaging

6. some mushrooms took as healing and preventive medicines a. some fungi used for longevity and spiritual energy (in China) b. eating mushroom improves blood circulation, reduce cholesterol level, lower

blood pressure, and boost the immune system c. some fungi have antitumor properties d. some fungi used to treat diabetes and cancer e. certain fungi enhance sexual energy f. certain fungi activate disease-engulfing macrophages and production of helper T-cells




Negative benefits of fungi

Some fungi species are destructive and disease-causing. The class Deuteromycetes (imperfect fungi) includes several disease-causing species of humans. Such diseases include

Aspergillosis of the respiratory tract

Athlete's foot

Ringworm

Deposited toe and fingernails Other fungi can attack the cellulose acetate of colour transparencies and film

They contaminate food products (pieces of bread and canned foods)

They stained (etch) glass lenses as they grow

Deadly species contain dangerous neurotoxins

Conclusion

This lecture is an eye-opener to the world of fungi, which many of us always ignore. By

now, we must have learnt how to recognise the common fungi and where to find them.

Fungi have not fully utilised. This observation is as a result of a lack of interest in the

study of Botany and inadequate funding for research.

Summary

Having studied this lecture note, we should have:

1. some understanding of poisonous and non-poisonous fungi

2. a better idea of the characteristics that separate them from plant and animal

3. getting ready to look around our environment for the common fungi

4. better awareness of the uses of fungi

References/Further readings

Sumbali G., Johri B. M. (2005). Class Basidiomycetes. In Johri B. M.(Ed). The Fungi.

Narosa Publishing House. New Delhi India.132-168.




CLASSCODE: DEPT.: MATRIC NO.:

Tutorial-marked questions

1. What is Androstenol? Explain its uses ___An extract from fungus (Truffles) ___Added to some cosmetics ___To attract opposite sex mates

2. State the popular mode of nutrition in fungi.

___Saprophytic mode and

___Parasitic mode

3. All mushrooms are poisonous. True or false.

___False

4. Give pieces of evidence to support the claim that fungi are neither plant nor animal

___They share characteristics of both plant and animal

___Plant characteristic include cellulose cell walls

___Animal characteristic include Chitin cell walls

Documents

KINGDOM: FUNGIstaff.oouagoiwoye.edu.ng/uploads/412_COURSES... · Deuteromycota (imperfect fungi) The first four divisions, to be discussed in this lecture, are grouped as heterotrophic