Fungi Relationships and Interactions

Human-Fungus Interactions

• Beneficial Effects of Fungi 
  • Decomposition - nutrient and carbon recycling. 
  • Biosynthetic factories. Can be used to produce drugs, antibiotics, alcohol, acids, food (e.g., fermented products, mushrooms). 
  • Model organisms for biochemical and genetic studies. 
• Harmful Effects of Fungi 
  • Destruction of food, lumber, paper, and cloth. 
  • Animal and human diseases (mycosis), including allergies. 
  • Toxins produced by poisonous mushrooms and within food (e.g., grain, cheese, etc.). 
  • Plant diseases. 

Ecological Impacts of Fungi

• Ecosystems depend on fungi as decomposers and symbionts: they decompose food, wood and even plastics!
• Some fungi are pathogens
  • Plants particularly susceptible (e.g. Dutch elm disease)
  • Ergot - affects cereal crops: causes gangrene, hallucinations and “St. Anthony’s fire”
• Many animals, including humans, eat fungi:
  • In US, mushroom consumption restricted to Agaricus
  • We eat a range of cultivated and wild mushrooms
  • Truffles are underground ascocarps of mycelia that are mycorrhizal on tree roots

Animal-Fungus Symbioses

• Some fungi share their digestive services with animals
• These fungi help break down plant material in the guts of cows and other grazing mammals
• Many species of ants use the digestive power of fungi by raising them in “farms”

Fungus-Plant Mutualisms

• Mycorrhizae are enormously important in natural ecosystems and agriculture
• Plants harbor harmless symbiotic endophytes
  • Endophytes: fungi that live inside leaves or other plant parts
• Endophytes make toxins that deter herbivores and defend against pathogens
• Most endophytes are ascomycetes