Mycology: Introduction

What is Mycology?

The scientific discipline dealing with fungi

Who are Mycologists?

They are scientists who study fungi

What are Mycoses?

The diseases that are caused by fungi

What does Myco stand for?

Fungus

What is studied in Mycology?

1. Structure

2. Taxonomy

3. Reproduction methods

4. Economical importance

What are the most important branches in Mycology?

1. Ecology

2. Physiology

3. Genetics

4. Industrial uses

5. Medical uses

Why do we study mycology?

Because its the most diverse organisms on earth.

Second to Insects.

How do you estimate the number of fungal species?

• Find the number of flowering plants in the area

  • most plant species are believed to be described

• Fund the number of fungi in the same area

• Find the ration of 6 fungi to each plant

Is a Fungus a eukaryote or prokaryote? Why?

Eukaryote, it contains a true nucleus and a nuclear membrane bound organelles

What are the characteristics of Fungi?

• Eukaryotes

• Lack chlorophyll

• Heterotrophs

• Glycogen is the primary carbohydrate storage product

• Chitin cell wall

• Single-cell or multi-cellular

• Can be Molds

  • Form hyphae

    • Form Mycelium

What are Molds?

Filamentous fungi that produce mycelium

What are Hyphae?

Long, branched, thread-like filaments

They can be

1. Septate

   • Hyphae that have cell walls between septa

2. Aseptate

   • Hyphae that do not have septa

   • Have a continuous cytoplasm mass

What is a Mycelium?

The total hyphal mass

A network formed by hyphae

How are Algae and Fungi similar?

Both have simple bodies called thallus

Which are not differentiated into

• Roots

• Stems

• Leaves

How are Algae and Fungi different?

Chlorophyll

• Algae contain chlorophyll

• Fungi do not contain chlorophyll

Mode of nutrition

• Algae are Autotrophic

• Fungi are Heterotrophic

Reserved food material

• Algae use Starch

• Fungi use Glycogen and Oil-Globules

Starch content

• Algae have starch

• Fungi starch is absent

What is a Haustoria? What is its perpose/function?

Root-like structure that grows INTO or AROUND another structure

Function: to absorb the water and nutrients from the structure.

What are the hyphal structure?

• Mycelium is usually highly developed as white growth

• Rhizomorphs

  • Hypha may grow very close and wound around one another

• Plectenchyma

  • The tissues formed by the closely associated hyphae

What are the 2 commonly seen fungal tissues?

1. Prosenchyma

   • Loose associated hyphae

   • Hyphal structure may be clearly seen

2. Pseudoparanchyma

   • Closely woven hyphae

   • NO intercellular spaces

   • Hyphae can NOT be seen

   • Ex. Sclerotium

What is the ultrastructure of fungal cells?

1. Cell wall

2. Plasma membrane

3. Cytoplasm and organelles

What is the Ultrastructure of fungal cells (Cell wall)?

• Composition is variable among different groups or same group but different species

• Lack cellulose

• Chitin as elongated variously oriented microfibrillar units

  • Laid down in layers

  • Basic of structural rigidity

What are the organelles found in the cytoplasm?

• Mitochondria

• Endoplasmic reticulum

• Vacuoles

• Golgi apparatus

• Nucleus

How do fungi obtain its nutrients? Explain.

By absorption

1. The nucleus sits at the back of the hyphae and directs it to the organic source

2. Hyphal tip releases enzymes

3. The released enzymes breakdown the substance

4. The products are diffused into the hyphae

Only some fungi are heterotrophic. (T/F)

False, ALL are heterotrophic

What are the 3 main ways fungi obtain nutrition?

• Parasitic

• Saprophytic

• Symbiotic

What are Parasitic fungi?

• Obligate or facultative

  • Obligate: Live on live host & does NOT kill the host

  • Facultative: Are Saprophytes. Kill host and feeds on it

• Food obtained from LIVING host

What are Saprophytic fungi?

• Nutrition obtained from Dead or decaying organic matter

• Obligate or facultative

  • Obligate: Remains saprophytic entire life

  • Facultative: Primarily parasite that has secondarily adopted saprophytic means

What are Symbiotic fungi?

• Mutualistic

• Form lichens

  • Enter mycorrhizal relationships

  • Enter relationships with algae

• 
  

What are Mycorrhiza?

Fungi that infect the plants roots and forming a

non-disease-producing association with the plant

About 90 percent of land plants rely on mycorrhizal fungi. (T/F)

True

Why do fungi have a great potential for quick adaptation?

The majority of the terrestrial forms are SAPROPHYTIC

They are also present all the time in air.

What are the 3 types of reproduction?

1. Vegetative

2. Asexual (Anamorph)

3. Sexual (Teleomorph)

In vegetative reproduction, the nuclei are united. (T/F)

False, There is no union of

• nuclei

• sex cells (gametes)

• sex organs.

Vegetative reproduction helps to increase the number of individuals in the population (T/F)

True

How does Vegetative reproduction in fungi occur?

• Fragmentation

• Fission

• Budding

• Sclerotia

• Rhizomorphs

How does Fragmentation happen in Vegetative reproduction?

The Mycelium breaks up into small fragments/pieces

Not all the fragmented pieces of the mycelium are able to develop into new individuals. (T/F)

False, all are able to develop into new individuals

How does Fission happen in Vegetative reproduction?

Common method of reproduction fission of yeast

1. Mature cell elongates

2. The nucleus divides into 2 daughter nuclei

3. The daughter nuclei separate

4. cytoplasm cleaves dividing the parent protoplasm into two daughter protoplasts.

5. A double cross wall is deposited in the middle

   • Septum

6. The middle layer of the double cross wall degenerates and the daughter cells are separated.

How does budding happen in Vegetative reproduction?

Common method in budding yeast

1. small outgrowth or bud emerges from the parent cell

2. nucleus of the parent cell divides into two

3. One of the nuclei is incorporated into the bud

4. may or may not be separated from the parent cell

   • When it is not a separated cell, it produces another bud.

     • resulting in the formation of a chain of buds called a pseudo-mycelium

What is Sclerotia and how is it formed in Vegetative reproduction?

They are compact masses of mycelium that survive for many years

They give rise to NEW mycelia when favorable conditions are met

Ex. Claviceps purpurae , Rhizoctonia solani

What is Rhizomorph and how is it formed in Vegetative reproduction?

A modified mycelium, rope-like

Resistant to unfavorable conditions

Give rise to NEW mycelia

Asexual reproduction is more common than Sexual reproduction. (T/F)

True

What are Sprors?

Specialized reproductive cells formed in Asexual reproduction

What is sporalation?

The formation of spores in fungi

Each spore develops into a new thallus. (T/F)

False, develops into a hyphae

Why are they called Mito-spores?

Because spores are produces as a result of mitosis in parent cells

Where are spores born from?

Sporophores

What do you call a fungi that produces more than 1 type of spore?

Multi-spored fun-guy!!

Pleomorphic or Polymorphic

What are Endogenous spores?

Spores produced INSIDE the Sporangium

What is a Sporangiophore?

Sporophores that bare the sporangia on their apices

The Sporangium can be branched or unbranched. (T/F)

True

What are the2 types of Endogenous spores?

1. Aplanospores

2. Zoospores

What are Zoospores?

• They are produced inside the zoosporangia

• They are motile

  • Uni/Bi-flagella

• No cell wall

• Uninucleate

• Vacuolate

• Kidney-shaped

• Flagella are inserted in 2 places

  • Posteriorly

  • Laterally

• FOUND IN LOWER FUNGI

  • Ex. Albugo , Phytophthora

What are Exogenous spores (Conidia)?

Spores produced on the terminal ends of Conidiophores

They are diverse in their

• Shape

• Size

• Color

• If they are unicellular or multicellular

• If they are uninucleate or multinucleate

What is a Conidiophore?

The part that produces conidia externally

Can be branched or unbranched

Why are spores important?

• Allow fungi to move to a new food source

• To survive periods of adversity

• to introduce new genetic combinations

Why are Aspergillus and Penicillium called blue green molds?

Their conidia are smoky green colored

What the specialized structures of Conidia?

1. Pycnidium

   • Flask-shaped

   • Produce: Pycniospores

2. Acervule

   • Saucer-shaped

     • Widely open body

   • Develop conidia in/on small conidiophores

3. Sporodochium

   • Small compact stroma

   • Stroma bears conidiophores on which asexual spores or conidia

4. Synnemata

   • Large erect reproductive structures

   • Bearing compact conidiophores that fuse together to form a strand with conidia at the end

How does Sexual reproduction in fungi occur?

• Spores form from the fusion of 2 opposite mating strains OF THE SAME FUNGUS SPECIES

• Consists of 3 phases

  1. Plasmogamy

  2. Karyogamy

  3. Meiosis

What happens in Plasmogamy?

The plasma of the gametes fuse together

That happens in Karyogamy?

The nuclei of the gametes fuse together

What happens in Meiosis?

Reduction division

What are the 3 methods of sexual reproduction?

1. Isogamy

   • Motile

   • Morphologically similar✅

   • Physiologically different❌

2. Heterogamy

   • Morphologically different

   • Physiologically different

3. Gametangial copulation

   • The fusion of the entire content of the gametangia

   • Form a Zygote/Zygospore

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