FUNGI

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C H A R A C T E R I S T I CS

STRUCTURE

bigger than a blue whale?

really???

REPRODUCTION

&EVOLUTIO

N

NOT FOR

THE…

squeamish!!!

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ECOLOGY

CHARACTERISTICS OF FUNGI

• eukaryotic • heterotrophic – secrete enzymes into food

and absorb digested materials through cell walls– most are saprophytic – absorb organic

materials from dead organisms, “nature’s recycler”

• many are microscopicBACK TO FUNGI HALL

STRUCTURE OF FUNGI• made up of hyphae (filaments), collectively

called mycelium

mycelium

• cell walls contain chitin (also found in insect and crustacean exoskeletons)– plant cell walls contain ???– eubacteria cell walls contain ???

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CELLULOSE!

PEPTIDOGLYCAN!

STRUCTURE OF FUNGI• cells can be coenocytic – have many nuclei or

have separated by septa – “walls”• range in size from microscopic (yeast) to the

largest organism in the world (Armillaria – 3.1 mi2)• some are dimorphic – can change form based on

environmental conditions, can grow as mycelium in soil or as unicellular organisms in humans (Histoplasma)

BACK TO FUNGI HALL

REPRODUCTION IN FUNGI

• reproduce both asexually (genetically identical offspring) and sexually

• most fungi are haploid throughout their life cycle

• sexual reproduction occurs when hyphae of different mating types

(+ and -) meet and fuse together

BACK TO FUNGI HALL

FUNGAL EVOLUTION evolved at about the same time as

early plants – 460 million years ago

BACK TO FUNGI HALL

THE FUNGAL

PHYLA

Rhizopus stolonifer(black bread mold)

•600 species•coenocytic

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Rhizopus mycelium(moldy strawberries)

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Spinellus fusiger - mushroom parasiteCONTINUED

Pandora neoaphidis - parasitic fungus that killsgreen peach aphids

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Zygomycota Life Cycle

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mature zygosporeCONTINUED

Rhinocerebral Zygomycosis –causes lesions of the palate,face and brain

Conidiobolus coronatis - causes polyps in the noseor masses under the skin,found in tropical areasCONTINUED

•25,000 species•form a basidiocarp, a reproductive structure also known as a mushroom!

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DEADLY MUSHROOMS

Some Amanita species associated with oak treescontain alpha-amanitin which works by slowly attacking RNA polymerase, an enzyme in the liver. It ultimately affects the central nervous system and kidneys. Death often results if a liver transplant or other heroic measures are not performed. CONTINUED

Chlorophyllum molubdites -most common cause ofmushroom poisoningin the US

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Omphallotis olearius dine on rotting tree stumps, yum!!!

CONTINUEDBACK TO FUNGI CHARACTERISTICS

Sexual Reproduction in Basidiomycota

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basidium and basidiospores

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bracket fungus - hemlock varnish shelf fungus

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coral fungus

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•30,000 species•believed to have evolved most recently•live in salt, freshwater and terrestrial habitats•phyla includes morels, powdery mildews, yeasts and cup fungi

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sac fungi

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Sexual Reproduction in Ascomycota

•hyphae of 2 mating strains form gametangiafemale - ascogonium male -

antheridium

•gametangia fuse and move into ascogonium, nuclei pair but do not fuse•cells divide mitotically, each heterokaryotic hyphae grows and intertwines to form an ascocarp (reproductive body)•asci form on the surface of the ascocarp, near the tips of some hyphae•each ascus has 2 nuclei that fuse•each diploid nucleus undergoes meiosis to produce 4 haploid nuclei•haploid nuclei divide once by mitosis so that each ascus ends up with 8 haploid ascospores•ascus ruptures to release ascospores that germinate

CONTINUED – yes, there is a diagram!

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Sexual Reproduction in Ascomycota

asci with 8 sporesin each

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Xylaria polymorpha -aka Dead Man’s Fingers, often foundat the base of beech trees

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Xylaria polymorpha cut in half (note the asci - the small black dots!)

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•10,000 species•no sexual reproductive phase has been discovered•many are similar to ascomycetes

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Athlete’s foot - caused by Tricophytom ruburm• lives within and eats outer skin layers (parasite)

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Ringworm - can be causedby the same organism thatcauses Athlete’s Footor other organisms, eats skin (parasite)

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Penicillium roqueforti…DE-licious

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Aspergillus can be a parasite(eye infection causedby Aspergillus)

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some organisms inthis phyla can beused to make soy sauce(soy beanfermentation)

BACK TO FUNGI HALL

ECOLOGICAL IMPORTANCE and IMPACT

of FUNGI

•may have helped early plants obtain nutrients through a symbiotic relationship

•played an important role in plant evolution 460 million years ago

•many fungi are plant parasites responsible for 15-20% of crop loss yearly CONTINUED

•play an essential role in maintaining equilibrium in every ecosystem (even the human body) by recycling nutrients, breaking down wastes and keeping other populations in check

•replace essential nutrients that plants remove from the soil

BACK TO FUNGI HALL

wheat rust - produces sporesin barberry plants that then migrate to wheat fields

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corn smut…not for popping

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SYMBIOSIS•lichens and mycorrhizea

•fungus is usually an ascomycete (can be a basidiomycete)

•photosynthetic organism is green algae or cyanobacteria

CONTINUED

•what does each organism get from the relationship ?

•what is the ecological importance of these organisms ?

lichens

BACK TO ECOLOGY

fungi provide moist shelter for the algae, while the algae provide a constant food supply (through photosynthesis) to their fungal host

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lichens are often the first organisms to inhabit barren areas (succession), creating soil by breaking down rock and adding organic nutrients (from their decay)

lichen growing on gneiss

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•mycorhizzae are symbiotic relationships between the roots of most plants and fungi•the fungi fix nitrogen so that it can be used by plants, while they use the plants as a shelter and food source