Lecture 7a: Fungal ecology

Question 1

Importance of decomposing fungi

Answer 1

• decrease litter and debris
• Nutrient cycling and energy flows in woody ecosystems
• Dominant carbon and organic nutrient recyclers

Question 2

Epiphytic fungi

Answer 2

• Colonise surfaces of living tissue, grow on simple soluble nutrients that leak from the host.
• Cause no harm to the plant
• can be beneficial in suppressing invasion by pathogens
• Thrives on honeydew

Question 3

Phyllosphere

Answer 3

Hostile environment; exposure to UV irradiation, fluctuation in temperature, moisture and nutrients

Question 4

Endophytes

Answer 4

• Grow in the intercellular fluids and wall spaces of their hosts
• cause no symptoms to the host
• non-host specific
• weak parasites and pathogens
• Can either tolerate or overcome host defences
  Utilise sugars and soluble nutrients
• Continue to grow on dead material

Question 5

Pionere Saprotrophic fungi (Ophiostoma ulmi)

Answer 5

Fungi found in soils, fecal-enriched material and rhizosphere
* Utilise sugars and simple soluble nutrients
* Colonise newly felled trees, grow in non-woody tissue and discolour the wood by darkly pigmented hyphae
* Cause no structural damage

Question 6

Polymer-degrading fungi

Answer 6

• Defend resources
• Can co-exist in a single substrate

Question 7

Trichoderma and fusarium species

Answer 7

• Cereal straw buried in the soil
• Fusarium species will be favoured by low water potential= drought tolerant
• Trichoderma favoured by acidic soil+ grow at pH of 3

Question 8

Secondary (opportunistic) Invaders

Answer 8

• Grow at any stage during decomposition
• Can grow in close associations with polymer degraders
• Can tolerate metabolic byproducts of other fungi
• Grow on dead material
• Utilise all decomposable material, leaving humid residues

Question 9

Mortierella

Answer 9

Live as saprotrophs in soil, on decaying leaves, on fecal sellers or exoskeletons of arthropods

Question 10

Degraders of recalcitrant compounds

Answer 10

• Capable of degrading lignocellulose to gain access to lignin and cellulose
• Keratin-degrading fungi- decomposition of hair of animals and hooves
• In later stages of decomposition

Question 11

Recalcitrant compounds

Answer 11

*Slowly biodegradable or non-biodegradable; physically and chemically complex polymers

Question 12

Fairy ring fungi

Answer 12

Cause fairy rings by feeding on decaying organic matter.
Usually don’t cause damage since the grow on dead material

Question 13

Decomposing fungi

Answer 13

• Continually deplete organic resources
• Need continual spread to new resources
• Their competitive ability determines if they are successful in colonisation and how they can retain the territory

Question 14

Life history strategies

Answer 14

• R-selected
• K/C-selected
• S-selected

Question 15

R-selected

Answer 15

Rudaral
* rapidly occupy a new habitat and they require readily available nutrients
* Explosive rates of reproduction

Question 16

K/C-seleted

Answer 16

Combative
* Establish and develop slowly, long life cycle and produce few offspring
* Compete with other fungi, protect their resources

Question 17

S-selected

Answer 17

Stress tolerance
* Grow in extreme environmental conditions: Extreme osmotic potential, heat, pH, mineral concentrations or lack of organic nutrients