Cells - fungal spore discharge

What is the problem of multi-cellularity in fungi?

• If a yeast cell lyses - only one cell dies

• If a hyphal cell lyses - all cells die

How do fungi overcome the issue of multi-cellularity?

• Damaged hyphal cells are isolated by Woronin bodies

• Are isolated by ‘plugging’

• Several Woronin bodies are concentrated around septal pores

What is the structure of Woronin bodies?

• Peroxisome-derived organelles containing crystals of self-assembled Hex1 protein

• Very stiff structures

What is the organisation of the basidiomycete fruiting body?

• The cap of the mushroom contains gills

• The gills contain the basidia with the spores attached

How do basidiomycetes drop their spores?

• Two water droplets are formed due to secretion of mannitol and other hygroscopic spores (attract water) on the spore surface

• The Buller’s drop increases in size due to recruitment of atmospheric water

• The sudden change in centre of gravity by fusion of both drops causes a propulsive force off of the basidiospore

• The wind takes the spores away to form a new individual

• Discharge distance is a maximum of a few millimetres

What are alternative spore discharge mechanisms?

• Moulds use air flow to release their spores

• Ascomycetes form specialised fruiting bodies - pressure from inside the ascus forces the spores out

• Internal pressure can release spores from asci (Pilobolus) - pressure builds up to 100-700kPa, shooting distance is from centimetres to up to 2 metres

• The ‘bird’s nest’ fungus produces a nest-shaped fruiting body with the spores inside - rain drops on the nest shape cause spores to be thrown out of the fruiting body