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General spore features
• Definition:– reproductive cells, capable
of developing into an adult without fusion with another cell
• Morphology – No embryo
– Nucleus + mitochondrion + food reserves
• Taxonomically informative
Is sporulation effective?• Species in equilibrium• On average, each individual
leaves only a single offspring little investment per spore
• Individual colonies produce massive numbers of spores– Calvatia ~ 7 trillion spores– Ganoderma ~ 30 billion spores a
day for 5 months– Aspergillus can produce >4
billion spores in 3 d (100mm dish)
Spore sizes
~ 80% spores are unicellular and <10µm in their longest dimension (smallest 2μm)
Largest 100 to 300 µm e. g. Glomus and Gigaspora
Longest Cordyceps militaris 2 µm x 500 µm asco
Spore dispersal – passive
dry conidia -- note must escape still air layer
aided by cupped structures such as apothecia and acervuli, which create turbulence
Nik Money has shown that mushroom caps are warm, presumably generating convection currents
Dispersal by water
• spores with slime coat, e.g. Stachybotrys, Gliocladium
• spores extruded into slime from deliquescing asci – stinkhorns
Dispersal by water
• inky cap mushrooms – Coprinus
• Bird’s nest fungi• dry conidia -- demo
Water dispersal in Nidulariales
Dispersal by animals
includes insects sticky spores
Stachybotrys scolytid beetles – Ceratocystis
stinky spores – Caninus
• insect feeding on basidiocarps – fly maggots – beetles
Animal dispersal, continued
birds Cryphonectria parasitica -- 1/3 of trees in
eastern US were sweet chesnut C. parasitica now used as important
commercial source of rennin
people Baker 1966 Inadvertant distribution of fungi
Can J Microbiol 12:109-112
Active spore dispersal
• requires effort (obvious) so cost/benefit analysis suggests there should be environmental sensing so that discharge is optimized
Ascobolus
Sarcoscypha
Asci with pore structures
Rhizocarpon obscuratumPeziza proteana sparassoides
Phototropic asci and spore releasethrough an operculum
Mushroom shape contributes to spore release
Active support for passive dispersal
Buller’s drop
www.anbg.gov.au/fungi
Convection currents and spore release in mushrooms
Deering et al 2001. Mycologia 93: 732-736
• Water evaporation into gill/pore space
• Water condensation onto hilar appendages
• Ballistic launch of spores
Trichoderma sporulation +/- light
Neurospora photoperiodicity
www.ux.his.no/~ruoff/Neurospora_Rhythm.html
Neurospora photoperiodicity
www.ux.his.no/~ruoff/Neurospora_Rhythm.html
Spore discharge in Sordaria- multiple triggers
- heirarchy of effect