Fungus-fungus Interactions

Question 1

What are the modes of attack and defence?

Answer 1

• antagonism at a difference
• hyphal interference
• mycoparasitism (hyphae lies tightly next to the surface of another, gains nutrition via piercing)
• gross mycelial contact

Question 2

Interaction outcomes

Answer 2

• deadlock
• replacement
• partial replacement
• mutual replacement

Question 3

Different types of chemical warfare

Answer 3

Enzymes
Diffusibles
Volatiles

Question 4

Pigment production during combat e.g.s

Answer 4

Produced by attacker or defender

• oxidation of phenolic by phenoloxidase and peroxidase
• sealing of hyphal boundaries via polymerisation of hydrophobins within hyphal walls (small group of proteins that create hydrophobic surface)

Question 5

Describe the production of volatiles

E.g. of 2 fungi

Answer 5

• caused by combative interactions
• fungi may respond to many volatiles at once
  E.g. H. Fasiculare and R. Bicolor
• Hf vs Hf = little spikes of volatiles (inhibit itself)
• Rb vs Rb = tiny spikes
• Hf vs Rb = large upregulation

Question 6

Gene expression changes during interactions

Answer 6

Used microarray analysis = expressed sequence tag changes in expression inc. genes involved in:

• bio synthetic processes
• ribsosomal proteins
• metabolism and proteolysis
• membrane associated functions
• cytoskeleton associated genes
• cell division
• nucleic acid binding
• stress responses
• signalling processes

Question 7

Lactase activity during combat study

Answer 7

Studied with T.versicolor;
Constructed cDNA libraries and looked at up/down regulation in deadlock, win and loss scenarios
- RNA extracted and PCR
- looked different parts of mycelium; at interaction zone, a bit back and further back
- laccase activity increased at interaction zone (v little elsewhere)

Question 8

Up/down regulation that occurs during antagonisms

Answer 8

Upregulation:
- enzymes; cellulose, phosphatase, chitinase
- components glycolytic pathway
- C and N metabolism
— stress mitigation compounds; cyclophilins, chaperones , heat shock proteins
Downregulate:
- biomass production

Question 9

Factors affecting interaction outcome

Answer 9

• venue e.g. soil, wood, agar
• microclimate
• quantity and quality of resources
• presence of other microorgs
• invertebrate grazing

Question 10

Fungus hierarchies

Answer 10

Transitive: A > B > C
Intratransitive: A > B, B > C, C > A
Different combative mechanisms against different species
- fungi are bullies = go for weakest even in group

• 1st orgs present in community are often poor combatants
• with development fungi that cope better with high competition and low resources thrive

Question 11

How do fungal battles alter fungi?

Answer 11

• the way they search for food
• where nutrients are stored in mycelia
• release of nutrients
• decay rate and Co2 evolution
• fungal community decay rate

Question 12

Extracellular enzymes produced during interactions

Answer 12

• ligninolytic enzymes

- cellulolytic enzymes

Question 13

Ligninolytic enzymes

Answer 13

laccase
Manganese peroxidase (MnP)
Manganese independent peroxidase (MIP)
Oxidases

Question 14

Cellulolytic enzymes

Answer 14

beta-glucosidase 
Alpha-glucosidase 
Acid phosphatase 
Exochitinase
Exocellualse
Phosphodiesterase 
Arylsulfatase 
Beta-xylosodase