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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
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
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
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
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
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
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
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
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
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 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 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
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 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