Chapter 22 Chapter 22

TheTheFungiFungi

Chapter 22

Fungal AnatomyFungal Anatomy

MulticellularMulticellularBody of almost all fungi is a Body of almost all fungi is a myceliummycelium, an , an interwoven mass of threadlike filaments interwoven mass of threadlike filaments called called hyphaehyphae (singular, hypha) (singular, hypha)

Chitin cell wallsChitin cell wallsHyphae of most species are divided into Hyphae of most species are divided into many cells by partitions called many cells by partitions called septasepta (singular, septum); each cell possesses (singular, septum); each cell possesses one or more nucleione or more nuclei• Pores in the septa allow cytoplasm to stream Pores in the septa allow cytoplasm to stream

from one cell to the nextfrom one cell to the next

Chapter 22The Filamentous BodyThe Filamentous Bodyof a Fungusof a Fungus

(a) Mycelium(a) Mycelium

(b) Individual Hyphae(b) Individual Hyphae

(c) Hyphal Cells (cutaway)(c) Hyphal Cells (cutaway)(c) Hyphal Cells (cutaway)(c) Hyphal Cells (cutaway)

Cell WallsCell WallsCell WallsCell Walls

SeptumSeptumSeptumSeptum

PorePorePorePore

CytoplasmCytoplasmCytoplasmCytoplasm HaploidHaploidNucleiNuclei

HaploidHaploidNucleiNuclei

Chapter 22

Chytrid FilamentsChytrid Filaments

MaleMaleMaleMale

FemaleFemaleFemaleFemale

Chapter 22

Fungal NutritionFungal Nutrition

Three major types of heterotrophic nutritionThree major types of heterotrophic nutrition

• Saprophytic—digestion of dead organismsSaprophytic—digestion of dead organisms

• Parasitic—digestion of live organismsParasitic—digestion of live organisms

• Symbiotic—mutual benefit of two Symbiotic—mutual benefit of two independent organismsindependent organisms

Chapter 22

Fungal ReproductionFungal Reproduction

AsexualAsexual• FragmentationFragmentation• Asexual spore formationAsexual spore formation

– Haploid mycelium produces haploid asexual Haploid mycelium produces haploid asexual spores by mitosisspores by mitosis

– Spores germinate and develop into a new Spores germinate and develop into a new mycelium by mitosismycelium by mitosis

Results in the rapid production of Results in the rapid production of genetically identical clonesgenetically identical clones

Chapter 22

Chapter 22

Fungal Sexual ReproductionFungal Sexual Reproduction

Typically occurs under conditions of Typically occurs under conditions of environmental change or stressenvironmental change or stress• Neighboring haploid mycelia of different, but Neighboring haploid mycelia of different, but

compatible mating types come into contact compatible mating types come into contact with each otherwith each other• The two different hyphae fuse so that the The two different hyphae fuse so that the

nuclei share a common cellnuclei share a common cell• The different haploid nuclei fuse to form a The different haploid nuclei fuse to form a

diploid zygotediploid zygote• Zygote undergoes meiosis to form haploid Zygote undergoes meiosis to form haploid

sexual sporessexual spores

Chapter 22Zygomycete Life Cycle (a)Zygomycete Life Cycle (a)

ZygosporeZygosporegerminatesgerminatesZygosporeZygosporegerminatesgerminates

SporangiaSporangiaSporangiaSporangia SporesSpores(haploid)(haploid)SporesSpores

(haploid)(haploid)

(b) Photo of Sporangia(b) Photo of Sporangia(b) Photo of Sporangia(b) Photo of Sporangia

Hyphae of Hyphae of opposite mating opposite mating

types fuse to types fuse to form zygospore.form zygospore.

Hyphae of Hyphae of opposite mating opposite mating

types fuse to types fuse to form zygospore.form zygospore.

HaploidHaploid11nn

DiploidDiploid2n2n

Chapter 22Zygomycete Life Cycle (b)Zygomycete Life Cycle (b)

Hyphae of Hyphae of opposite mating opposite mating

types (+ & -) fuse.types (+ & -) fuse.

Hyphae of Hyphae of opposite mating opposite mating

types (+ & -) fuse.types (+ & -) fuse.

NUCLEI FUSENUCLEI FUSE

DiploidDiploidZygosporeZygospore

formedformed

MEIOSISMEIOSIS

ZygosporeZygosporegerminatesgerminatesZygosporeZygosporegerminatesgerminates

DiploidDiploid22nn

HaploidHaploid11nn

Chapter 22Classification of FungiClassification of Fungi

Fungi have been assigned to four phyla Fungi have been assigned to four phyla based upon the way they produce based upon the way they produce sexual sporessexual spores• Chytridiomycota (chytrids)Chytridiomycota (chytrids)• Zygomycota (zygote fungi)Zygomycota (zygote fungi)• Ascomycota (sac fungi)Ascomycota (sac fungi)• Basidiomycota (club fungi)Basidiomycota (club fungi)

Chapter 22

Chapter 22

The ChytridsThe Chytrids

ChytridsChytrids•Most are aquaticMost are aquatic• Reproduce both asexually and sexuallyReproduce both asexually and sexually• Form flagellated spores that require Form flagellated spores that require

water for dispersalwater for dispersal• Figure 22-4Figure 22-4, p. 426,, p. 426, illustrates the chytrid illustrates the chytrid

fungus fungus AllomycesAllomyces in the midst of sexual in the midst of sexual reproductionreproduction

Chapter 22

Chapter 22

The ChytridsThe ChytridsMost feed on dead aquatic materialMost feed on dead aquatic materialSome species are parasites of plants Some species are parasites of plants and animalsand animals• One chytrid species is a frog pathogen One chytrid species is a frog pathogen

believed to be a major cause of the believed to be a major cause of the current worldwide die-off of frogscurrent worldwide die-off of frogs

Primitive chytrids are believed to have Primitive chytrids are believed to have given rise to the other groups of given rise to the other groups of modern fungimodern fungi

Chapter 22

ZygomycetesZygomycetes

Most live in soil or on decaying plant or Most live in soil or on decaying plant or animal materialanimal material

Reproduce both asexually and sexuallyReproduce both asexually and sexually• Sexual spores are thick-walled Sexual spores are thick-walled zygosporeszygospores

During asexual reproduction:During asexual reproduction:• Haploid spores are produced via mitosis Haploid spores are produced via mitosis

in black spore cases called in black spore cases called sporangiasporangia• Spores disperse and germinate to form Spores disperse and germinate to form

new haploid hyphaenew haploid hyphae

Chapter 22

ZygomycetesZygomycetes

During sexual reproductionDuring sexual reproduction• Two hyphae of different mating types come Two hyphae of different mating types come

into contact and fuseinto contact and fuse• Nuclei fuse to form a diploid Nuclei fuse to form a diploid zygosporezygospore, a , a

tough, resistant structure that can remain tough, resistant structure that can remain dormant for long periods until conditions are dormant for long periods until conditions are favorablefavorable• Meiosis occurs as the zygospore germinatesMeiosis occurs as the zygospore germinates• Resulting spores disperse and germinate to Resulting spores disperse and germinate to

form new haploid hyphae that can enter either form new haploid hyphae that can enter either the asexual or sexual cyclethe asexual or sexual cycle

Chapter 22

Chapter 22

Chapter 22

Chapter 22

AscomycetesAscomycetesLive in a variety of marine, freshwater, Live in a variety of marine, freshwater, and terrestrial habitatsand terrestrial habitats

Reproduce both asexually and sexuallyReproduce both asexually and sexually• Sexual spores form in saclike Sexual spores form in saclike asciasci

During asexual reproductionDuring asexual reproduction• Haploid spores are produced via mitosis Haploid spores are produced via mitosis

at the tips of specialized hyphae at the tips of specialized hyphae • Spores disperse and germinate to form Spores disperse and germinate to form

new haploid hyphaenew haploid hyphae

Chapter 22AscomycetesAscomycetes

During sexual reproductionDuring sexual reproduction• Two hyphae of different mating types Two hyphae of different mating types

come into contact and fuse, resulting in come into contact and fuse, resulting in the formation of a fruiting bodythe formation of a fruiting body

Chapter 22

Chapter 22

AscomycetesAscomycetes

Better known examples includeBetter known examples include•Most of the food-spoiling moldsMost of the food-spoiling molds•Morels and truffles (edible delicacies)Morels and truffles (edible delicacies)• PenicilliumPenicillium, the mold that produces , the mold that produces

penicillin (the first antibiotic)penicillin (the first antibiotic)• Yeasts (single-celled fungi)Yeasts (single-celled fungi)

Chapter 22

Some AscomycetesSome Ascomycetes

(a) Scarlet Cup Fungus(a) Scarlet Cup Fungus

(b) Morel(b) Morel

Chapter 22BasidiomycetesBasidiomycetes

Live in a variety of marine, freshwater, Live in a variety of marine, freshwater, and terrestrial habitatsand terrestrial habitats

Usually reproduce sexuallyUsually reproduce sexually• Sexual spores form in club-shaped Sexual spores form in club-shaped

basidiabasidia

During sexual reproduction:During sexual reproduction:• Two hyphae of different mating types Two hyphae of different mating types

come into contact and fuse, resulting in come into contact and fuse, resulting in the formation of a fruiting bodythe formation of a fruiting body

Chapter 22

Basidiomycete Life CycleBasidiomycete Life Cycle

HaploidHaploid11nn

DiploidDiploid22nn

Mushroom gillsMushroom gillsbear reproductivebear reproductive

basidia.basidia.

BasidiaBasidiaon gillson gills

Haploid NucleiHaploid Nuclei Fusion forms Fusion forms diploid zygote.diploid zygote.

MEIOSISMEIOSIS

MEIOSISMEIOSIS

BasidiosporesBasidiospores(haploid)(haploid)

Chapter 22

Basidiomycete Life CycleBasidiomycete Life Cycle

HaploidHaploid11nn

DiploidDiploid22nn

BasidiaBasidiaon gillson gills

BasidiosporesBasidiospores(haploid)(haploid)

““+” Mating+” MatingStrainStrain

““+” Mating+” MatingStrainStrain ““-” Mating-” Mating

StrainStrain““-” Mating-” Mating

StrainStrainBasidiospores germinateBasidiospores germinateforming hyphae (haploid).forming hyphae (haploid).

++++----Hyphae fuse, butHyphae fuse, buthaploid nucleihaploid nuclei

remain separateremain separatein binucleate cellsin binucleate cells

Hyphae aggregateHyphae aggregateto form mushroomto form mushroom

Chapter 22

BasidiomycetesBasidiomycetes

Better known examples includeBetter known examples include•Mushrooms (some are edible, others are Mushrooms (some are edible, others are

poisonous)poisonous)• PuffballsPuffballs• Shelf fungi (decomposers of wood)Shelf fungi (decomposers of wood)• StinkhornsStinkhorns• Rusts and smuts (plant parasites)Rusts and smuts (plant parasites)• YeastsYeasts

Chapter 22

Some BasidiomycetesSome Basidiomycetes

(a) Giant Puffball (a) Giant Puffball (b) Shelf Fungi (b) Shelf Fungi

Chapter 22

Fairy RingsFairy Rings

A fairy ring is a circular pattern of A fairy ring is a circular pattern of mushroom growthmushroom growth

Fairy rings form at the leading edge of Fairy rings form at the leading edge of an expanding underground fungal an expanding underground fungal myceliummycelium• The wider the diameter of the ring, the The wider the diameter of the ring, the

older the myceliumolder the mycelium• Some fairy rings are estimated to be 700 Some fairy rings are estimated to be 700

years oldyears old

Chapter 22

A Mushroom Fairy RingA Mushroom Fairy Ring

Chapter 22

Symbiotic RelationshipsSymbiotic Relationships

A A symbiosissymbiosis is a close interaction is a close interaction between organisms of different species between organisms of different species over an extended period of timeover an extended period of time

The fungal member of a symbiotic The fungal member of a symbiotic relationship may be harmful (a parasite relationship may be harmful (a parasite of plants or animals) or beneficial of plants or animals) or beneficial (lichens and mycorrhizae)(lichens and mycorrhizae)

Chapter 22LichensLichens

LichensLichens are symbiotic associations are symbiotic associations between fungi (usually an ascomycete) between fungi (usually an ascomycete) and algae or cyanobacteria and algae or cyanobacteria • Fungus provides photosynthetic partner Fungus provides photosynthetic partner

with shelter and protectionwith shelter and protection• Photosynthetic partner provides fungus Photosynthetic partner provides fungus

with food (sugar)with food (sugar)

Chapter 22Lichens:Lichens:Symbiotic PartnershipsSymbiotic Partnerships

Algal LayerAlgal Layer

Fungal HyphaeFungal Hyphae

AttachmentAttachmentStructureStructure

Chapter 22

LichensLichens

Grow on a wide variety of materials Grow on a wide variety of materials (soils, tree trunks and branches, rocks, (soils, tree trunks and branches, rocks, fences, roofs, and walls)fences, roofs, and walls)

Are able to survive environmental Are able to survive environmental extremes (newly formed volcanic extremes (newly formed volcanic islands, deserts)islands, deserts)

Are very diverse in formAre very diverse in form

Chapter 22

Lichens Covering a RockLichens Covering a Rock

Chapter 22

MycorrhizaeMycorrhizaeMycorrhizaeMycorrhizae (singular, mycorrhiza) are (singular, mycorrhiza) are symbiotic associations between fungi symbiotic associations between fungi and plant roots and plant roots • Fungus provides plant with water, minerals, Fungus provides plant with water, minerals,

and organic nutrients it absorbs from the and organic nutrients it absorbs from the soilsoil• Plant provides fungus with food (sugar)Plant provides fungus with food (sugar)

80% of plants with roots have mycorrhizae80% of plants with roots have mycorrhizaeRelationship may have helped plants Relationship may have helped plants colonize landcolonize land

Chapter 22MycorrhizaeMycorrhizaeEnhance Plant GrowthEnhance Plant Growth

MycorrhizaeMycorrhizaeMycorrhizaeMycorrhizae

Chapter 22

RecyclersRecyclers

Fungi are Earth’s undertakers, feeding Fungi are Earth’s undertakers, feeding on the dead of all kingdomson the dead of all kingdoms

Fungal Fungal saprophytessaprophytes (feeding on dead (feeding on dead organisms) release extracellular organisms) release extracellular substances that digest the tissues of substances that digest the tissues of the dead and liberate carbon, nitrogen, the dead and liberate carbon, nitrogen, phosphorus compounds, and minerals phosphorus compounds, and minerals that can be reused by plantsthat can be reused by plants

Chapter 22

Fungi Attack PlantsFungi Attack Plants

Fungal parasites cause the majority of Fungal parasites cause the majority of plant diseasesplant diseases• Ascomycete parasites cause Dutch elm Ascomycete parasites cause Dutch elm

disease and Chestnut blightdisease and Chestnut blight• Rusts and smuts are basidiomycete Rusts and smuts are basidiomycete

parasites that cause considerable parasites that cause considerable damage to grain cropsdamage to grain crops

Chapter 22

Corn SmutCorn Smut

Chapter 22

Fungi Cause Human DiseasesFungi Cause Human DiseasesAthlete’s foot, jock itch, and ringworm Athlete’s foot, jock itch, and ringworm are caused by fungi that attack the skinare caused by fungi that attack the skin

Valley fever and histoplasmosis are Valley fever and histoplasmosis are caused by fungi that attack the lungscaused by fungi that attack the lungs• Infection occurs when victim inhales Infection occurs when victim inhales

sporesspores

Most vaginal infections are caused by Most vaginal infections are caused by the yeast the yeast Candida albicansCandida albicans

Chapter 22

YeastsYeasts

CandidaCandida sp. sp.CandidaCandida sp. sp.

Chapter 22Fungi Produce ToxinsFungi Produce Toxins

Claviceps purpureaClaviceps purpurea (an ascomycete) (an ascomycete) produces several toxinsproduces several toxins• Infects rye plants and causes ergot Infects rye plants and causes ergot

diseasedisease• Symptoms of ergot poisoning include Symptoms of ergot poisoning include

vasoconstriction of blood vessels, vasoconstriction of blood vessels, vomiting, convulsive twitching, vomiting, convulsive twitching, hallucinations, and deathhallucinations, and death

PenicillinPenicillin• First antibiotic to be discoveredFirst antibiotic to be discovered• Used to combat bacterial diseasesUsed to combat bacterial diseases

Chapter 22

PenicilliumPenicillium

Chapter 22Fungi Contribute to GastronomyFungi Contribute to Gastronomy

Certain ascomycete molds impart flavor to Certain ascomycete molds impart flavor to some of the world’s most famous cheesessome of the world’s most famous cheeses• RoquefortRoquefort• CamembertCamembert• StiltonStilton• GorgonzolaGorgonzola

Yeasts are used in the production of wine, Yeasts are used in the production of wine, beer, and breadbeer, and bread

Wine is produced when yeasts ferment fruit Wine is produced when yeasts ferment fruit sugars; ethyl alcohol is retained, while COsugars; ethyl alcohol is retained, while CO22 is releasedis released

Chapter 22Fungi Contribute to GastronomyFungi Contribute to Gastronomy

Beer is derived when yeasts ferment sugars in Beer is derived when yeasts ferment sugars in germinating grains (usually barley); ethyl germinating grains (usually barley); ethyl alcohol and COalcohol and CO22 are retained are retained

Bread rises when yeasts ferment sugar that Bread rises when yeasts ferment sugar that has been added to bread dough; both ethyl has been added to bread dough; both ethyl alcohol and COalcohol and CO22 escape during baking escape during baking

Some fungi are consumed directlySome fungi are consumed directly• Mushrooms (a basidiomycete)Mushrooms (a basidiomycete)• Morels (an ascomycete)Morels (an ascomycete)• Truffles (an ascomycete)Truffles (an ascomycete)

Chapter 22

TrufflesTruffles

Chapter 22

Fungal IngenuityFungal Ingenuity

The truffle has evolved an effective The truffle has evolved an effective adaptation for dispersal of its sporesadaptation for dispersal of its spores• Releases an odor which causes pigs and Releases an odor which causes pigs and

other animals to dig it up, scattering other animals to dig it up, scattering spores to the windsspores to the winds

The zygomycete The zygomycete PilobolusPilobolus has evolved has evolved bulb tops that blast off, spreading bulb tops that blast off, spreading sporesspores

Chapter 22PilobolusPilobolus::An Explosive ZygomyceteAn Explosive Zygomycete

Chapter 22

Fungal IngenuityFungal Ingenuity

ArthrobotrysArthrobotrys cleverly traps and cleverly traps and “strangles” microscopic roundworms “strangles” microscopic roundworms called nematodes to obtain nutrientscalled nematodes to obtain nutrients

Chapter 22

The Nemesis of NematodesThe Nemesis of Nematodes

Special hyphaSpecial hyphawith noosewith noose

UnfortunateUnfortunatenematodenematode

Chapter 22 Chapter 22

TheTheEndEnd