The FungiChapter 23

The FungiThe Fungi 2

OutlineOutline

CharacteristicsCharacteristicsStructureStructureReproductionReproduction

EvolutionEvolutionSac FungiSac FungiYeastsYeastsClub FungiClub FungiSmuts and RustsSmuts and Rusts Imperfect FungiImperfect Fungi

Symbiotic RelationshipsSymbiotic Relationships

The FungiThe Fungi 3

Characteristics of the FungiCharacteristics of the Fungi

Kingdom Fungi contains 80,000 sppKingdom Fungi contains 80,000 spp

Mostly multicellular eukaryotes that Mostly multicellular eukaryotes that share a common mode of nutritionshare a common mode of nutrition

HeterotrophicHeterotrophic

Cells release digestive enzymes and Cells release digestive enzymes and then absorb resultant nutrient then absorb resultant nutrient moleculesmolecules

Some are parasiticSome are parasitic

Several have mutualistic relationshipSeveral have mutualistic relationship

The FungiThe Fungi 4

Structure of FungiStructure of Fungi

Body (thallus) of most fungi is multicellular Body (thallus) of most fungi is multicellular mycelium (yeasts are unicellular)mycelium (yeasts are unicellular)Consists of a vast network of thread-like Consists of a vast network of thread-like hyphaehyphae­Septate fungi have hyphae with cross wallsSeptate fungi have hyphae with cross walls­Nonseptate fungi are multinucleatedNonseptate fungi are multinucleated­Hyphae grow from tipHyphae grow from tip

Give the mycelium a large surface area per Give the mycelium a large surface area per unit volumeunit volume

Cell walls of chitin, like insect exoskeletonCell walls of chitin, like insect exoskeletonExcess food stored as glycogen as in animalsExcess food stored as glycogen as in animalsPossibly evolved from red algae - both lack Possibly evolved from red algae - both lack flagellaflagella

5Mycelia and Hyphae of Fungi

The FungiThe Fungi 6

Reproduction of FungiReproduction of Fungi

Both sexual (in most) and asexual Both sexual (in most) and asexual reproductionreproduction

Sexual reproduction involves three Sexual reproduction involves three stages:stages:

Haploid HyphaeHaploid Hyphae

Dikaryotic StageDikaryotic Stage

Diploid ZygoteDiploid Zygote

The FungiThe Fungi 7

Reproduction of FungiReproduction of Fungi

During sexual reproduction, hyphae from During sexual reproduction, hyphae from two different mating types fusetwo different mating types fuse

Hyphae that contain paired haploid nuclei Hyphae that contain paired haploid nuclei are said to be dikaryoticare said to be dikaryotic

Nuclear fusion produces diploid nucleus, Nuclear fusion produces diploid nucleus, which produces haploid windblown spores which produces haploid windblown spores by meiosisby meiosis

Spores germinate directly into haploid Spores germinate directly into haploid hyphae without embryological developmenthyphae without embryological development

Asexual reproduction usually involves the Asexual reproduction usually involves the production of windblown sporesproduction of windblown spores

Unicellular yeasts reproduce by buddingUnicellular yeasts reproduce by budding

8Dispersal of Spores

The FungiThe Fungi 9Diversity of Fungi:Diversity of Fungi:ZygomycotaZygomycota

Zygospore FungiZygospore Fungi

Phylum ZygomycotaPhylum Zygomycota

Mainly saprotrophs decomposing Mainly saprotrophs decomposing animal and plant remainsanimal and plant remains

Black bread mold - Black bread mold - Rhizopus Rhizopus stoloniferstolonifer

10Black Bread Mold,

Rhizopus stolonifer

The FungiThe Fungi 11Diversity of Fungi:Diversity of Fungi:ZygomycotaZygomycota

Life cycleLife cycle Hyphae of opposite mating types grow toward Hyphae of opposite mating types grow toward each othereach other

Hyphae swell at tips; cross walls develop behind Hyphae swell at tips; cross walls develop behind each end; form gametangiaeach end; form gametangia

Gametangia merge resulting in a large multi-Gametangia merge resulting in a large multi-nucleate cellnucleate cell

­ Nuclei of the two mating types pair and then fuseNuclei of the two mating types pair and then fuse

­ A thick wall develops around the zygosporeA thick wall develops around the zygospore

The zygospore becomes dormant for periodThe zygospore becomes dormant for period

Sporangiophore(s) then sporangia develop, Sporangiophore(s) then sporangia develop, spores releasedspores released

Spores dispersed by air currents; germinate into Spores dispersed by air currents; germinate into myceliamycelia

The FungiThe Fungi 12Diversity of Fungi:Diversity of Fungi:Sac FungiSac Fungi

Phylum Ascomycota - about 60,000 species of sac Phylum Ascomycota - about 60,000 species of sac fungifungi

Most are saprotrophs that digest resistant Most are saprotrophs that digest resistant materials containing cellulose, lignin, or collagenmaterials containing cellulose, lignin, or collagen

Most are composed of septate hyphaeMost are composed of septate hyphaeNeurosporaNeurospora, experimental organism for the one-, experimental organism for the one-gene-one-enzyme studiesgene-one-enzyme studies

Morels and truffles, famous gourmet delicacies Morels and truffles, famous gourmet delicacies revered throughout the worldrevered throughout the world

Many plant diseases: Powdery mildews; leaf curl Many plant diseases: Powdery mildews; leaf curl fungi; ergot of rye; chestnut blight and Dutch elm fungi; ergot of rye; chestnut blight and Dutch elm diseasedisease

AspergillusAspergillus and and CandidaCandida cause serious human cause serious human infectionsinfections

TalaromycesTalaromyces (formerly (formerly PenicilliumPenicillium) is source of ) is source of penicillinpenicillin

The FungiThe Fungi 13Sac Fungi:Sac Fungi:Reproduction - Asexual Reproduction - Asexual

Life cycleLife cycleAsexual reproduction is the normAsexual reproduction is the norm

Yeasts usually reproduce by buddingYeasts usually reproduce by budding­ A small bulge forms on side of cell A small bulge forms on side of cell ­ Receives a nucleus and gets pinched off and Receives a nucleus and gets pinched off and becomes full sizebecomes full size

The other ascomycetes produce spores called The other ascomycetes produce spores called conidia or conidiosporesconidia or conidiospores

Vary in size and shape and may be multicellularVary in size and shape and may be multicellular Conidia usually develop at the tips of conidiophores Conidia usually develop at the tips of conidiophores

­ Conidiophores differ in appearance and are Conidiophores differ in appearance and are diagnosticdiagnostic

­ Conidia are windblownConidia are windblown­ Conidia of Conidia of CladosporiumCladosporium cause allergies - cause allergies - concentrations of more than 35,000 conidia/mconcentrations of more than 35,000 conidia/m33 over Leiden (Germany)over Leiden (Germany)

14Asexual Reproduction in Sac Fungi

The FungiThe Fungi 15Sac Fungi:Sac Fungi:Reproduction - SexualReproduction - Sexual

Life cycle, cont.Life cycle, cont.

Sexual reproductionSexual reproductionAscus refers to the fingerlike sac that Ascus refers to the fingerlike sac that develops during sexual reproductiondevelops during sexual reproduction

Asci usually surrounded and protected by Asci usually surrounded and protected by sterile hyphae within an ascocarpsterile hyphae within an ascocarp­ In cup fungi, ascocarps are cup-shapedIn cup fungi, ascocarps are cup-shaped­ In morels they are stalked and are pitted In morels they are stalked and are pitted like the surface of the moonlike the surface of the moon

Haploid hyphae fuse to make diploid Haploid hyphae fuse to make diploid nucleusnucleus

Mitosis and then meiosis produces 8 Mitosis and then meiosis produces 8 ascosporesascospores

16Sexual Reproduction in Sac Fungi

17Black Mold

18Tineas

The FungiThe Fungi 19Sac Fungi:Sac Fungi:Reproduction - YeastsReproduction - Yeasts

Term “yeasts” is loosely applied to Term “yeasts” is loosely applied to unicellular fungi, many of which are unicellular fungi, many of which are ascomycetesascomycetes

Budding is common form of asexual Budding is common form of asexual reproductionreproduction

Sexual reproduction results in the Sexual reproduction results in the formation of asci and ascosporesformation of asci and ascospores

When some yeasts ferment, they When some yeasts ferment, they produce ethanol and carbon dioxideproduce ethanol and carbon dioxide

The FungiThe Fungi 20Diversity of Fungi:Diversity of Fungi:The Club FungiThe Club Fungi

Phylum Basidomycota – 22,000 sppPhylum Basidomycota – 22,000 spp

Familiar toadstools, mushrooms, Familiar toadstools, mushrooms, bracket fungi, puffballs, stinkhorns – bracket fungi, puffballs, stinkhorns – some deadly poisonoussome deadly poisonous

Also plant diseases such as the smuts Also plant diseases such as the smuts and rustsand rusts

Mycelium composed of septate hyphaeMycelium composed of septate hyphae

The FungiThe Fungi 21The Club Fungi:The Club Fungi:ReproductionReproduction

Usually reproduce sexuallyUsually reproduce sexually

Haploid hyphae fuse, forming a Haploid hyphae fuse, forming a dikaryotic (n + n) myceliumdikaryotic (n + n) mycelium

Dikaryotic mycelium forms fruiting Dikaryotic mycelium forms fruiting bodies called basidiocarpsbodies called basidiocarps

Contain club-shaped structures called Contain club-shaped structures called basidiabasidia

Nuclear fusion followed by meiosis Nuclear fusion followed by meiosis produces basidiospores (up to produces basidiospores (up to 40,000,000 per hour)40,000,000 per hour)

22Club Fungi

23Club Fungi

The FungiThe Fungi 24The Club Fungi:The Club Fungi:Smuts and RustsSmuts and Rusts

Smuts and rusts are club fungi that parasitize Smuts and rusts are club fungi that parasitize cereal cropscereal crops Great economic importance because of annual Great economic importance because of annual crop lossescrop losses­ Do not form basidiocarpsDo not form basidiocarps

Life cycle of rusts often requires two different Life cycle of rusts often requires two different plant host species plant host species Black stem rust of wheat uses barberry bushesBlack stem rust of wheat uses barberry bushes Blister rust of white pine uses currant and Blister rust of white pine uses currant and gooseberry bushesgooseberry bushes

Eliminating these bushes in crop areas keeps Eliminating these bushes in crop areas keeps rusts in checkrusts in check

Wheat rustWheat rust­ Controlled by breeding new resistant strains of Controlled by breeding new resistant strains of wheatwheat

­ Requires continuous development, because rust Requires continuous development, because rust can mutatecan mutate

25Smuts & Rusts

The FungiThe Fungi 26Symbiotic Relationships:Symbiotic Relationships:LichensLichens

Symbiotic association between a fungus Symbiotic association between a fungus and a cyanobacterium or green algaand a cyanobacterium or green alga

Specialized fungal hyphae penetrate Specialized fungal hyphae penetrate photosynthetic symbiontphotosynthetic symbiont

Transfer nutrients directly to the fungusTransfer nutrients directly to the fungus

Possibly mutualistic, but fungal symbiont Possibly mutualistic, but fungal symbiont probably a parasite of photosynthetic probably a parasite of photosynthetic symbiontsymbiont

Photosynthetic symbiont independentPhotosynthetic symbiont independent

Fungal symbiont usually can’t grow aloneFungal symbiont usually can’t grow alone

The FungiThe Fungi 27Symbiotic Relationships:Symbiotic Relationships:LichensLichens

Three morphological types Three morphological types

Compact crustose lichens - seen on Compact crustose lichens - seen on bare rocks or on tree barkbare rocks or on tree bark

Fruticose lichens – shrub-likeFruticose lichens – shrub-like

Foliose lichens - leaf-likeFoliose lichens - leaf-like

Can live in areas of extreme Can live in areas of extreme conditions and contribute to soil conditions and contribute to soil formationformation

Sensitive indicators of air pollutionSensitive indicators of air pollution

28Lichen Morphology

The FungiThe Fungi 29Symbiotic Relationships:Symbiotic Relationships:MycorrhizaeMycorrhizae

Mutualistic relationships between soil fungi Mutualistic relationships between soil fungi and the roots of most familiar plantsand the roots of most familiar plants

Give plant greater absorptive surfaceGive plant greater absorptive surface

Help plants acquire mineral nutrients in poor Help plants acquire mineral nutrients in poor soilsoil

Fungal symbiont usually a sac fungusFungal symbiont usually a sac fungus

Hyphae may enter cortex of root, but not Hyphae may enter cortex of root, but not cytoplasmcytoplasm

­ Ectomycorrhizae form a mantle that is exterior Ectomycorrhizae form a mantle that is exterior to the root, and they grow between cell walls.to the root, and they grow between cell walls.

­ Endomycorrhizae penetrate only the cell wallsEndomycorrhizae penetrate only the cell walls

Earliest fossil plants have mycorrhizae Earliest fossil plants have mycorrhizae associated with themassociated with them

The FungiEnding Slide Chapter 23