General spore features Definition: –reproductive cells, capable of developing into an adult...

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