Fungal Interactions
All life is dependent on the interactions between fungus and other organisms, from plant roots to nutrient cycling
Fungi and Decomposition
- Decomposers: break down dead organics into usable minerals
- Most fungi break down plant lignin
- Important, lignin is hard to break down
- Important for CO2 and nutrient cycle
- Release C and N trapped in dead matter
Soil Formation
- Lichens: symbiotic relationship between fungal hyphae and photosynthetic algae
- Fungus gets protection and nutrients
- Algae gets more nutrients
- Colonize disturbed habitat
- Aided colonization of land plants
- Most symbionts are in Ascomycota and Basidiomycota
Plant Mutualism
- Mycorrhiza: Mutualistic Symbiosis between plant roots and fungus
- Fungus gets sugars
- Plant gets nutrients (N)
- Fueled the colonization of land plants
- Obligate: both must occur together, can't survive independently
Animal Mutualism
- Exist in herbivore guts, aid in digestion
- Leaf-cutter ants farm fungus
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Fungi as Parasites
Fungi can also feed off of living tissue, this causes many diseases in humans and other animals. This is also a major issue in agricultural crops.
Fungi and Plants
- 2nd biggest threat to plants (insects first)
- Necroses: fungi digests living plant tissue Examples: blight, cankers, scab
- Wilt: Plants loose their structure
- Powdery Mildew: Fungi coats leaves and fruit, hyphae penetrates surface cells Example: Dutch Elm Disease
- caused by fungus Ophiostoma ulmi
- Disease spread via Black Beetles
Fungi and Invertebrates
- Invertebrate Parasites
- Fungi that infect insects and arachnids
- Spores produced inside of host
- Sometimes produces fruiting body to burst out of host
- Invertebrate Predators
- Some fungi function like predators Example: Nematode traps
- Catches another organism and strangles it to death
Fungi and Vertebrates
- Vertebrate Parasites
- Mycosis: fungal disease in vertebrates (humans)
- infects terrestrial and aquatic vertebrates
- Cutaneous Infection: infects outer layers of skin Example: Ringworm
- Causes a ring of hyphae around infection
- Localized Subcutaneous Infection: infects wounds
- Spores in environment colonize open wound
- Systemic Infection: Whole body is infected
- Opportunistic Fungal Disease
- Typically harmless fungi infect other parts of body Example: Yeast
- Common in gut and moist skin
- Can infect other skin when moist = diaper rash
- Can infect mucous membrane (if normal microflora / chemical conditions change)
- Other Human Fungal Diseases
- Histoplasmosis: common systemic mycosis
- Inhale from bird / bat droppings
- Can also be cutaneous
- Fungi transitions from hyphae to yeast
- Yeast can invade host cells
- Results in systemic infection => death
- Especially dangerous for immune compromised individuals